MST5

MStower V5

UUsseerr’’ss MMaannuuaall

Engineering Systems

COPYRIGHT NOTICE(C) Copyright Engineering Systems (EEC) Limited 1997-2000. All rights are reserved. The copyright applies tothis manual and to the corresponding software (together referred to herein as the “licensed material”).

DISCLAIMERSubject to limitations imposed by law, Engineering Systems (EEC) Limited makes no warranty of any kind inconnection with the licensed material. Engineering Systems (EEC) Limited shall not be liable for any errorscontained in the licensed material nor for any incidental or consequential damages resulting from the furnishing oruse of the licensed material. Engineering Systems (EEC) Limited is not engaging in the provision of consultingservices in furnishing the licensed material. Users of the licensed material are advised that output from computersoftware should be subjected to independent checks. Engineering Systems (EEC) Limited reserves the right torevise and otherwise change the licensed material from time to time without notification, or provision of revisedmaterial.

SOFTWARE LICENCESoftware is supplied to the user under licence. The software may be installed on multiple computers but thenumber of concurrent users must be limited to the number of licences held. The software may not be sub-licensed,rented, or leased to another party. The licence can only be transferred to another party at the discretion ofEngineering Systems (EEC) Limited.

Engineering Systems (EEC) LimitedSystems House27 Highclere DriveHemel Hempstead HERTS HP3 8BYEngland

Tel: +44 (0) 144 226 2647E-mail: [email protected]: www.microstran.com

March, 2000

Crystal Palace Tower, LondonThis is Britain’s tallest unguyed steel tower. It was checked for structural adequacy using MStower.

MStower V5

UUsseerr’’ss MMaannuuaall

Engineering Systems

COPYRIGHT NOTICE(C) Copyright Engineering Systems Pty Limited 1997-2000. All rights are reserved. The copyright applies to thismanual and to the corresponding software (together referred to herein as the “licensed material”).

DISCLAIMERSubject to limitations imposed by law, Engineering Systems Pty Limited makes no warranty of any kind inconnection with the licensed material. Engineering Systems Pty Limited shall not be liable for any errorscontained in the licensed material nor for any incidental or consequential damages resulting from the furnishing oruse of the licensed material. Engineering Systems Pty Limited is not engaging in the provision of consultingservices in furnishing the licensed material. Users of the licensed material are advised that output from computersoftware should be subjected to independent checks. Engineering Systems Pty Limited reserves the right to reviseand otherwise change the licensed material from time to time without notification, or provision of revisedmaterial.

SOFTWARE LICENCESoftware is supplied to the user under licence. The software may be installed on multiple computers but thenumber of concurrent users must be limited to the number of licences held. The software may not be sub-licensed,rented, or leased to another party. The licence can only be transferred to another party at the discretion ofEngineering Systems Pty Limited.

Engineering Systems Pty Limited14 Eastern RoadPO Box 85Turramurra NSW 2074Australia

Tel: +612 9488 9622Fax: +612 9488 7883E-mail: [email protected]: www.microstran.com.au

March, 2000

Crystal Palace Tower, LondonThis is Britain’s tallest unguyed steel tower. It was checked for structural adequacy using MStower.

Preface

MStower is a software package for the analysis and design of towers and masts. This softwareincorporates the very latest in Windows technology to make it easier to use and improve yourproductivity.

“1:Introduction” provides an overview of the capabilities of MStower. Whether you are installingMStower for the first time or updating an existing system, you will find all the necessary informationin “2:Getting Started”. “3:Menus & Toolbars” provides a summary of the commands available andother chapters provide reference and technical information.

This manual is available to the MStower user on-line, together with “pop-up” help for toolbar buttonsand dialog boxes. The on-line Help system provides a synchronized table of contents and powerfulmethods of searching for topics.

If the file Readme.TXT is present in the MStower folder after installation, you should read it forinformation that became available after the manual was printed. The file is automatically displayedduring installation but it may be displayed in Notepad at any time by double-clicking the file inWindows Explorer.

MSTower V5 Contents • i

Contents

1:Introduction 1General ......................................................................................................................................1Acknowledgement.....................................................................................................................3Enhancement Record ................................................................................................................3

2:Getting Started 5Installing MStower....................................................................................................................5Hardware Lock..........................................................................................................................5Folders.......................................................................................................................................6Starting MStower ......................................................................................................................8Commands ................................................................................................................................9Right-Clicking Away from Any Part of the Tower...................................................................9How to Make a Shortcut on the Desktop ................................................................................10Launch with Double-Click ......................................................................................................10Configuration ..........................................................................................................................11Printing in MStower................................................................................................................12

Print and Print Preview Commands ..........................................................................12The Windows Print Dialog Box................................................................................12The Page Setup Dialog Box......................................................................................13Example: Printing Reports On a Laser Printer, Graphics On a Color Inkjet.............14

Steel Section Libraries ............................................................................................................14Data from Earlier Versions .....................................................................................................14Technical Support ...................................................................................................................15

3:Menus & Toolbars 17Layout .....................................................................................................................................17File Menu Commands .............................................................................................................18View Menu Commands...........................................................................................................19Tower Menu Commands.........................................................................................................20Member Checking Menu Commands......................................................................................20Structure Menu Commands.....................................................................................................21Analyse Menu Commands ......................................................................................................22Results Menu Commands .......................................................................................................22Reports Menu Commands.......................................................................................................23Show Menu Commands ..........................................................................................................23Query Menu Commands .........................................................................................................24Window Menu Commands......................................................................................................25

ii • Contents MSTower V5

Help Menu Commands........................................................................................................... 26Main Toolbar Commands ....................................................................................................... 26View Toolbar Commands....................................................................................................... 27Display Toolbar Commands ................................................................................................... 28Help Toolbar Commands........................................................................................................ 28Draw Toolbar Commands....................................................................................................... 29Attributes Toolbar Commands ............................................................................................... 29Results Toolbar Commands.................................................................................................... 30OK/Cancel Toolbar Commands ............................................................................................. 30Extra Buttons Toolbar Commands ......................................................................................... 31Selecting Which Toolbars Are Displayed .............................................................................. 31Customizing Toolbars............................................................................................................. 32The Ouput Window ................................................................................................................ 32

4:Operation 33Data Files................................................................................................................................ 33

Units ......................................................................................................................... 34Axes ......................................................................................................................... 34Sections .................................................................................................................... 34Member Checking .................................................................................................... 35

Errors ...................................................................................................................................... 35

5:Tower Data 37General ................................................................................................................................... 37The Tower Data (TD) File...................................................................................................... 38

Title Block................................................................................................................ 39Component Block..................................................................................................... 39Profile Block ............................................................................................................ 40Supports Block ......................................................................................................... 46Guys Block............................................................................................................... 47Sections Block.......................................................................................................... 48Material Block.......................................................................................................... 51Bolt Data Block........................................................................................................ 52Guy Library .............................................................................................................. 54

6:Standard Panels 55Index – Face Panels ................................................................................................................ 56Index – Plan Bracing .............................................................................................................. 60Index – Hip Bracing & Cross-Arms ....................................................................................... 61D & V Face Panels ................................................................................................................. 62X Face Panels ......................................................................................................................... 63K Face Panels ......................................................................................................................... 67M Face Panels......................................................................................................................... 75W Face Panels ........................................................................................................................ 77XMA Face Panel .................................................................................................................... 78DM Face Panel ....................................................................................................................... 79DMH Face Panel .................................................................................................................... 80

MSTower V5 Contents • iii

DLM & DRM Face Panels......................................................................................................81KXM Face Panel .....................................................................................................................82XDMA Face Panel ..................................................................................................................83Plan Bracing............................................................................................................................84Hip Bracing .............................................................................................................................88Cross-Arms .............................................................................................................................90

7:User-Defined Panels 91General ....................................................................................................................................91The UDP File ..........................................................................................................................92Making A UDP Using Graphics Input ....................................................................................96UDP Example .........................................................................................................................97Modifying An Existing UDP.................................................................................................100Towers With Unequal Length Legs ......................................................................................100

8:Graphics Input for UDPs 101General ..................................................................................................................................101Basic Drawing.......................................................................................................................102The Drawing Snap Mode ......................................................................................................104The Drawing Plane................................................................................................................105Automatic Removal of Duplicate Nodes and Members........................................................105Cursors ..................................................................................................................................106Shortcut Keys........................................................................................................................107Selecting Nodes and Members..............................................................................................107Right-Clicking on Nodes and Members................................................................................108The Node Properties Dialog Box ..........................................................................................109The Member Properties Dialog Box .....................................................................................109Properties Dialog Boxes with Multiple Selection .................................................................110Extrusion ...............................................................................................................................110Interrupting Commands ........................................................................................................110The Stretch Command...........................................................................................................111The Limit Command .............................................................................................................112Removing an Intermediate Node...........................................................................................113

9:Tower Loading 115General ..................................................................................................................................115The Tower Loading (TWR) File ...........................................................................................116

Parameters Block ....................................................................................................116Terrain Block ..........................................................................................................118Velocity Profile Block ............................................................................................121Named Node Block.................................................................................................122Guy List Block........................................................................................................123Loads Block ............................................................................................................123Wind Load Cases ....................................................................................................124Guyed Mast Patch Loadings ...................................................................................125Dead Loads .............................................................................................................126Ice Loads.................................................................................................................126

iv • Contents MSTower V5

Miscellaneous Loads .............................................................................................. 127Additional Node Loads .......................................................................................... 127Additional Member Temperatures ......................................................................... 127Combination Load Cases........................................................................................ 128Panel Block ............................................................................................................ 128Ancillary Block ...................................................................................................... 128

Output ................................................................................................................................... 135Method.................................................................................................................................. 136

BS 8100.................................................................................................................. 136CP3 Chapter 5 ........................................................................................................ 136AS 3995.................................................................................................................. 136Malaysian Electricity Supply Regulations 1990 .................................................... 137EIA/TIA-222-F....................................................................................................... 137BS 8100 Gust Factor Correction ............................................................................ 138

Ancillary Libraries................................................................................................................ 138Large Ancillary Library.......................................................................................... 139Linear Ancillary Library ........................................................................................ 141Drag Coefficients ................................................................................................... 141

10:CAD Interface 143General ................................................................................................................................. 143Exporting a CAD DXF ......................................................................................................... 143Exporting a Steel Detailing Neutral File............................................................................... 144Windows Clipboard Operations ........................................................................................... 144

11:Analysis 145General ................................................................................................................................. 145

Method ................................................................................................................... 146Consistency Check ................................................................................................. 146Accuracy ................................................................................................................ 146

Linear Elastic Analysis ......................................................................................................... 147Non-Linear Analysis............................................................................................................. 147

Second-Order Effects ............................................................................................. 148Running a Non-Linear Analysis............................................................................. 150Troubleshooting Non-Linear Analysis ................................................................... 154

Elastic Critical Load Analysis .............................................................................................. 155Selecting Load Cases for ECL Analysis................................................................. 156Analysis Control Parameters .................................................................................. 156Why ECL Analysis Sometimes Gives High k Factors ........................................... 157

Dynamic Analysis................................................................................................................. 157Analysis Control Parameters .................................................................................. 158Dynamic Modes ..................................................................................................... 159Dynamic Analysis Example ................................................................................... 159

Response Spectrum Analysis................................................................................................ 160Running a Response Spectrum Analysis ................................................................ 160Response Spectrum Curves .................................................................................... 163

Errors .................................................................................................................................... 164

MSTower V5 Contents • v

12:Member Checking 167General ..................................................................................................................................167Operation...............................................................................................................................167Design Loads.........................................................................................................................168Member Checks to BS 8100: Part 3 (DD 133)......................................................................168Member Checks to BS 449 ...................................................................................................169Member Checks to AS 3995 .................................................................................................170Member Checks to ASCE 10-90 1991 ..................................................................................171Member Checks to EIA-222-F 1998 .....................................................................................172Obtaining Design Results......................................................................................................174Steel Detailing.......................................................................................................................174Editing the Steel Section Library ..........................................................................................175Editing Ancillary & Guy Libraries........................................................................................180

13:Examples 181TWEX1 & TWEX10-US ......................................................................................................184

14:Ancillary Programs 193CTIDATA .............................................................................................................................193

Glossary 195

Index 197

MSTower V5 1:Introduction • 1

1:Introduction

GeneralMStower is a specialized program that assists in the analysis andchecking of latticed steel communication and power transmission towersand guyed masts. MStower contains options for defining the geometry,loading, analysis, plotting of input, results, and member checking.Loading may be computed in accordance with:

• BS 8100:Part 1 1986. • BS 8100:Part 4 1995• CP3 Chapter 5• AS 3995-1994• Malaysian Electricity Supply Regulations 1990.• EIA/TIA-222-F-1996.

Member capacities may be checked against the requirements of:• BS 8100:Part 3 (DD133:1986)• BS 449• AS 3995-1994.• ASCE 10-90 1991• EIA/TIA-222-F-1996

Towers, which may be of three or four sides, are assembled bycombining a series of standard face, plan, hip and cross-arm panels. Thetower profile is defined by giving the height of individual panels and thewidth at “bend” points. All other widths are obtained by interpolation.The range of standard panels is being regularly increased with over 100different panel types available at present. A number of the standardpanels are parameterised so that the user may readily modify theconfiguration.If a suitable standard panel is not available the system accepts “user-defined panels” (UDP). While these require much more data than astandard panel, they allow the system to be used for virtually any towerconfiguration. A UDP may consist of anything from a few members that

2 • 1:Introduction MSTower V5

make up half a face panel to a full three-dimensional section of thetower.The result of the tower building process is a complete MStower data file,Job.MST, where “Job” is the MStower job name.The loading module of MStower computes loads due to self-weight, ice,and wind on the tower. As well as computing wind loads on the baretower the program is able to take account of a wide range of ancillaryitems found on communication towers.Ancillaries are classified into the following categories:• Linear ancillaries, normally within the body of the tower and

consisting of items such as ladders, feeders and wave-guides.• Face ancillaries, attached to the face of the tower and consisting of

small items such as minor antennae, gusset plates and platforms.• Large ancillaries, mounted out from the face of the tower and

consisting of large dishes whose wind resistance is significantcompared with that of the structural members of the tower.

• Insulators, located between the segments of multi-segment guys.Ancillary libraries containing data describing the physical and dragcharacteristics of a wide range of antennae types are provided withMStower. The libraries are plain text files and may be easily added to byusers. For a dish antenna the library would typically include its diameter,mass, location of center of gravity, surface area that may be coated withice, and its projected area and a drag coefficients for a range of angles ofincidence.Six aerodynamic coefficients are specified for each angle of incidence toenable antenna forces and moments to be computed automatically.The use of ancillary libraries simplifies the preparation of the dataneeded to compute the loads on the tower. To fully describe an antennaits library reference, its location on the tower, and its bearing arerequired. MStower will extract all other data from the library, computethe forces acting on the antenna (dead load, ice-load, and wind loads)and transfer them into the tower as a set of statically equivalent forces.To assist in checking of input data MStower displays the tower and alllinear and large ancillaries. As well as the visual display, any ancillarymay be queried by “picking” with the graphics cursor to obtain itsidentification, location, library reference, and other pertinent data.Wind forces may be computed using either gust or mean wind velocity.In the latter case, the member forces for wind load cases are increasedafter analysis using gust factors computed in accordance with BS 8100.For masts, patch wind loading cases may be computed and combined inaccordance with BS 8100:Part 4.The strength of members may be checked against the rules of the codeslisted above, with the results available as a summary report giving thecritical load case and condition or a larger detailed report suitable forchecking the computations for each member. The results of the member

MSTower V5 1:Introduction • 3

check may be shown as a graphical display with the color in which amember is displayed depending on its maximum load/capacity ratio.Foundation reactions and ancillary rotations may also be reported.

AcknowledgementInitial development of sections of MStower was done under contractswith the Independent Broadcasting Authority, Eastern Electricity, BritishTelecom, and the British Broadcasting Corporation.Particular recognition is due to Mr M J Lambert of the IndependentBroadcasting Authority who initiated this work.

Enhancement RecordVersion 3.1New menu introduced.TWR file format revised.Terrain blocks introduced.Linear and large ancillary libraries introduced.32 bit version of programs introduced.Additional standard panels introduced.GUST and MEAN keywords added to TWR file.Graphical input of UDPs introduced.

Version 3.15Screen querying of linear ancillary, large ancillary, and ancillary groupsintroduced with graphical representation of larger ancillaries.Ancillary libraries extended to include Andrew information.HP LaserJet printers now supported for plotting.PostScript format available for output files.Ancillary deflections and rotations calculated.Foundation reactions calculated.CROSS and BARE keywords added.Total mass and additional mass of ancillaries in TWR file.XIP, plan bracing at intersection point of face bracing.Optional Velocity Profile.

Version 4Masts including catenary cables to BS 8100:Part 4 and AS 3995.Additional standard panels.

4 • 1:Introduction MSTower V5

Named node block introduced.Supports block.Version 4.1EIA/TIA-222-F-1996.ASCE 10-90 1991 (Manual 52).Bolt checking to DD133/BS5950.Deflections/rotations.

Version 4.15Manual re-set in Microsoft Word.Examples revised.Partial safety factors for materials now applied at member checkingstage.Database utilities added.Bolt data file included.

Version 4.20Shade factor introduced for linear and large ancillaries.Job.OUT file enhanced for results checking.

Version 4.21Tension-only members now available in UDPs; non-linear analysismodule required.

Version 5.00New 32-bit Windows version. Ancillary display improved; split viewwith ancillary labelling. Database recognition and automatic loadingfrom CSV files. Enhanced metafile export of views. Non-linear analysisconvergence parameters added. Smear loading for wind on guys. UDPinput completely revised. Support for DOS discontinued.Generation of TD and TWR files. Multi-segment guys and guyinsulators supported. Asymmetrical ice loading added. Bolt checking toAS 3995, EIA-222, and ASCE 10-90 added.

MSTower V5 2:Getting Started • 5

2:Getting Started

Installing MStowerThe Setup program will install MStower on your computer. Usually,Setup will begin when you insert the CD. If Setup does not beginautomatically you must perform these steps:• Click on the Windows Start button and select Run.• Browse to the Setup program on the distribution CD.• Execute the Setup program.Setup will guide you through the installation process, prompting you fora name for the program folder (the default is C:\Mstower), and thencopying the required files to the hard disk. Any required fonts will beinstalled if they are not already installed.

Hardware LockMost systems are supplied with a hardware lock that must be pluggedinto a printer port before you can start MStower. Additional informationon the hardware lock is supplied on a data sheet.Additional setup procedures are described on a data sheet for WindowsNT/2000 and network versions.

6 • 2:Getting Started MSTower V5

FoldersThe Setup program will establish a number of folders under the specifiedMStower folder. If you use the default name the folders as displayed inWindows Explorer will look like this:

MSTOWER FOLDERS

Folder Name CommentMstower MStower folder – you can choose this name during

installation. “Mstower” is the default.

.....Data Default data folder – you can open MStower files in otherfolders if you wish.

.....Drivers Folder for hardware lock drivers, network lock drivers, anddocumentation files. This folder is created optionally duringinstallation.

.....Examples Example files – useful for testing and learning.

.....Program All MStower program files, library files, and Help files.


Library File FolderYou may use the File > Configure > General > Library File Foldercommand to specify a folder for library files anywhere on the computeror in the Network Neighborhood. Files in this folder will be accessedwhen you refer to a library file with the “L:” prefix. Using the “P:”prefix will cause MStower to look in the Program folder for library files.Library file references that do not have a prefix cause MStower to lookin the data folder for library files.


Temporary File FolderBy default, MStower writes intermediate data to the Windows temporaryfile folder. This is usually most satisfactory for all types of installation.You may, however, use the File > Configure > General > TemporaryFile Folder command to specify a different folder anywhere on thecomputer or in the Network Neighborhood.

Starting MStowerThe Setup program creates an MStower item on the Windows Programsmenu (click Start, then Programs). Click on this item to start MStower .If you have not previously used MStower you should start with some ofthe examples supplied with MStower to familiarize yourself with theoperation of the principal menu and toolbar items (see “13:Examples” onpage 177). To run an example, use the File > Open command and click onthe required file in the dialog box.You may open any existing MStower job with the File > Opencommand. To start a new job based on an old job, open the old job andsave a copy with another name using the File > Save Copy Ascommand. You may now close the old job and open the new copy byselecting its name from the most recently used list on the File menu.Note the following powerful Help features, which make it easier for youto use MStower:• There are tooltips on all toolbar buttons. Move the mouse cursor

over the button for a moment and a little pop-up window displaysthe function of the button.

• There is a prompt displayed on the left side of the status bar (at thebottom of the MStower window) whenever the cursor is positionedover a toolbar button or a menu item. Look here for prompts whileyou are performing input operations.

• Context-sensitive help is available for all toolbar buttons by clickingthe button. Once you have clicked this button, move the newcursor to any item and click.

• Context-sensitive (pop-up) help is available in dialog boxes. Someitems in dialog boxes also have tooltips.

Use the Help > MStower Help Topics command to display the HelpTopics dialog box. With this, you can browse the table of contents, lookthrough an index, or search all Help topic keywords.


CommandsMStower commands are available from:

• The main menu.• Toolbar buttons.• The context menu.

Generally, all the commands are available on the main menu, while, forconvenience, some of them are also available on toolbar buttons or thecontext menu. Commands selected from the main menu are referred to inthis manual as shown in this example:View > Zoom > WindowCommands selected by clicking a toolbar button are referred to by thename of the button, as shown in the tooltip.

Right-Clicking Away from Any Part of the TowerWhen you right-click in the main window, away from any node ormember, the pop-up menu below appears.

MAIN CONTEXT MENU

This provides a very convenient alternative to the main menu for manycommands. In effect, you can perform some operations in three differentways. For example, you can display the section number on all membersby clicking a button on the Display toolbar, by selecting the View >Display Options command, or by right-clicking and then selectingSection Numbers.


How to Make a Shortcut on the DesktopTo make a shortcut to MStower on your desktop (the background that isvisible when no programs are running), right-click on the desktop, selectNew > Shortcut, and in the Create Shortcut dialog box browse to theMst.EXE file in the MStower program folder. Set the “Start in” folder tothe MStower data folder. Enter MStower for the name of the shortcut,and click the Finish button.

Launch with Double-ClickMStower job files (Job.MST, where “Job” is the job name) should beidentified in Explorer with a distinctive icon. It is convenient to be ableto double-click on one of these files in Explorer to start MStower withthe job. To do this, the MST file type must be associated with MStower.The association between MStower and the MST file type may beestablished when MStower is installed. You may also establish theassociation with the procedure set out below.Here are the steps necessary to make MStower launch with a double-click:• In Explorer select the View > Folder Options or View > Options

command.• Select the File Types tab.• In the list box search for the MStower job file type, which may be

shown as “MST File” or “MStower Document”. If found, select thisfile type and click the Remove button. Close the dialog box.

• In Explorer browse to the MStower data folder and double-click onany MStower job file (if the file name extension “MST” is notvisible you may see it by right-clicking and checking the propertiesof the file).

• The Open With dialog box appears. Click on the Other button andbrowse to Mst.EXE in the MStower program folder.

• In the Description box type “MStower Job File” and click OK.• In Explorer select the View > Folder Options or View > Options

command.• Select the File Types tab, then select “MStower Job File” in the list

box and click the Edit button.• Click the Change Icon button and then select the second icon.• Click OK to close the Edit File Type dialog box.• Click OK to close the Folder Options dialog box.Now, check that you have successfully set up your system by browsingto an MStower job file and double-clicking.


ConfigurationThe first time you start MStower it will run in a partial screen window.Maximize the Window (use the button next to the X button at the top rightof the MStower window) and the system will thereafter start in a full-screen window.Toolbars may be activated or de-activated using the View > Toolbarscommand and they may also be floated or moved to different locationson the main window if desired (“docked”). Toolbar buttons may bedragged from one toolbar to another while the Alt key is held down.Chapter 3 contains more information on how you can customize thetoolbars.The File > Configure command allows you to set program parameterssuch as colors, default library files and design codes, and maximum jobsize. The default settings for maximum job size will be sufficient for themajority of jobs. Increasing limits unnecessarily can result in slightlyreduced operating speed.

FILE > CONFIGURE


Printing in MStower

Print and Print Preview CommandsMStower differs from many standard Windows application in that thereis a requirement to print both files (reports) and pictures. As in astandard Windows application, MStower has a Print command on theFile menu (File > Print File). This is for printing files and reports. Also,there is a Print command on the View menu (View > Print View) andthis is used for printing pictures of the structure. The File menu is shownin “File Menu Commands” on page 16 and the View menu is shown in“View Menu Commands” on page 17.In addition to Print commands on the File and View menus, MStowerhas Print Preview commands on each of these menus. The print previewshows an exact image on the screen of the printed page. File > PrintPreview shows you how a report will be printed while View > PrintPreview is for MStower graphics.The main toolbar, usually located right under the menu, contains a Printbutton, , and a Preview button, . These buttons are for MStowergraphics, not files or reports. Thus, they correspond to the Print andPreview commands on the View menu – notice that the tooltip for thePrint button is “Print View”. The main toolbar is shown in “MainToolbar Commands” on page 24.

The Windows Print Dialog BoxWhile the Preview button acts exactly the same way as thecorresponding menu command, the Print button does not. The View >Print View command displays the Windows Print dialog box so you canchange the target printer, the number of copies, or printer settings withthe Properties button. When you click OK in this dialog box the selectedprinter becomes the current printer. The File > Print File command alsodisplays the Windows Print dialog box before printing. Clicking the printbutton on the main toolbar, however, initiates a graphics print withoutthe display of the Windows Print dialog box. The view is printedimmediately to the current printer.

WINDOWS PRINT DIALOG BOX


Preview commands, File > Print Preview, View > Print Preview, andthe Preview button, all do not display the Windows Print dialog box. Thepreview is always for the current printer. When you see a print previewon the screen, you will notice a Print button at the top left of the previewwindow. Clicking this will initiate printing on the current printer. If youwant to change the target printer after seeing a preview, close thepreview window and then select the Print command on either the File orthe View menu. When previewing a multi-page report file, the Printbutton prints the whole file. If you want to print less than the full reportuse the File > Print File command and select the pages to be printed inthe Windows Print dialog box.

The Page Setup Dialog BoxAs well as offering the ability to change printer settings independentlyfor reports and graphics, the Page Setup dialog box offers theconvenience of configuring MStower’s default printer independently ofthe Windows default printer. Thus, you may select your preferred printerfor MStower output knowing that it will be selected every time you startMStower , regardless of which printer is selected as the Windows defaultprinter. While MStower is running, the Windows default printer ischanged to match the MStower default printer and when MStower stops,the original Windows default printer is restored. The default printerbecomes the current printer and remains so until a different printer isselected in the Windows Print dialog box. The first time you runMStower (or if the configuration file is deleted), the Windows defaultprinter is selected in the Page Setup dialog box. You may select anyother printer in this dialog box and the next time MStower runs thisprinter will still be selected.

MSTOWER PAGE SETUP DIALOG BOX

You may print reports or graphics to a printer that is not selected in thePage Setup dialog box by choosing it in the Windows Print dialog box,displayed on File > Print File and View > Print View. The selectedtarget will then be the current printer. Selecting a new target printer willnot change the printer selected in the Page Setup dialog box.


Example: Printing Reports On a Laser Printer,Graphics On a Color InkjetLet’s say the laser printer (black and white) is the Windows defaultprinter because most applications use it for output. It would probably bemost convenient for the same printer to be configured as MStower’sdefault printer – select it in the Page Setup dialog box, click OK, and itwill become the MStower default printer. Now, when you print graphicsyou may occasionally need a color plot. Select the View > Print Viewcommand and when the Print dialog box is shown, select the colorprinter. The color printer becomes the current printer. When yousubsequently print a report with the File > Print File command you willhave a chance to change the target back to the laser printer. While thecolor printer is the current printer, if you preview a report and click thePrint button, the report will be printed on the the color printer.

Steel Section LibrariesA source file is supplied with each steel section library. The source file isa text file with the file name extension “ASC” and the correspondinglibrary file has a file name extension of “LIB” (e.g. Asw.ASC,Asw.LIB). To make a new library, copy an existing source file to a filewith a new name and modify it as required. Use the File > Configure >Edit Library command to modify a library (see “Editing the SteelSection Library” on page 171). It is recommended that you do not modifythe standard library supplied with MStower – it is preferable to copy itto a file with a different name and then modify that.Steel section libraries used with DOS versions of MStower arecompatible with those used by Windows versions (V5.0 and later).

Data from Earlier VersionsMStower V5 is file-compatible with V3 and V4. All data files (TD,TWR, UDP) and section and ancillary libraries from V3 and V4 arecompatible with MStower V5.


Technical SupportMStower technical support is available by telephone, fax, and e-mail.Use the Help > About MStower command to display the serial number,the exact version number, and the configuration of your software. Thisinformation is required when you ask for technical support. In addition,the Help About dialog box contains hot-links directly to the MStowerWeb Site on the Internet and to e-mail Support.

HELP ABOUT MSTOWER

The MStower Web Site is a useful source of additional information andprovides a facility that allows licensed users to download updates to thesoftware.

MSTower V5 3:Menus & Toolbars • 17

3:Menus & Toolbars

LayoutThe diagram below shows the layout of the MStower screen. Commandsmay be initiated from the main menu, any toolbar, or a context (pop-up)menu. The main menu comprises a menu bar, each item of which givesaccess to a drop-down menu. Some items on drop-down menus lead tosub-menus. Each toolbar button usually corresponds to a commandaccessible from the main menu. Context menus, which appear when youclick the right mouse button, contain a selection of commands from themain menu. This chapter lists all the commands available on the mainmenu and all toolbars.

18 • 3:Menus & Toolbars MSTower V5

LAYOUT OF MSTOWER WINDOW

File Menu Commands

FILE MENU

The File menu offers the following commands:

Command ActionNew Creates a new job.Open Opens an existing job.Close Closes the current job.Save Saves the current job using the same file name.Save As Saves the current job to a specified file name and changes

the name of the current job accordingly.Save Copy As Saves a copy of the current job to a specified file name.Delete Deletes job files, optionally keeping source files.List/Edit File Opens the selected file with the MsEdit text editor for

viewing or editing.Page Setup Change the printing options.Print Preview Displays the selected file on the screen, as it would appear

printed.Print File Prints the selected file.Export Writes MStower data to a file for input to another program.

Also used for saving job to an MStower archive file.Configure Configuration of program capacity, section library, material

library, colors, intermediate file folder, and timed backupinterval. Also used for editing of section and materiallibraries and dynamic response spectra.


Recent Job Selects recently used job.Exit Exits MStower

View Menu Commands

VIEW MENU

The View menu offers the following commands:

Command ActionToolbars Shows or hides the toolbars.Status Bar Shows or hides the status bar.Redraw Redraws the current view.Limit Select a part of the structure by one of several available

methods. Unselected parts are shown in light grey orhidden.

Full Redraws the current view so that it fills the window.Zoom Change the scale of the view or select a rectangular part of

the view to fill the display window.Pan Displace the view by the selected distance.Viewpoint Change the orientation of the structure in the view by

selecting a new viewpoint.Copy Copy view to Windows clipboard in EMF format.Print Preview Displays the view as it would appear printedPrint View Prints the view.Display Options Select options for displaying node numbers, member

numbers, etc.Ancillary SortOrder

Specify whether ancillaries will be sorted by serial numberor height.

Model View Displays a rendered 3-D interactive view of the towermodel. (Not yet implemented.)


Tower Menu Commands

TOWER MENU

The Tower menu offers the following commands:

Command ActionBuild Tower Opens the tower data (TD) file for editing and

processing. Includes graphical creation of user-definedpanels.

Load Tower Opens the tower loading (TWR) file for editing andprocessing.

Analyse Analyses the tower.Gust Factor Applies gust factoring to wind forces in tower members.Build/Load/Analyse Runs all the previous items sequentially.

Member Checking Menu Commands

MEMBER CHECKING MENU

The Member Checking menu offers the following commands:

Command ActionBS 8100 Part 3 Checks members to the rules of BS 8100 Part 3.BS 449 Checks member to the rules of BS 449.AS 3995 Checks member to the rules of AS 3995.ASCE 10-90 Checks member to the rules of ASCE 10-90.EIA-222-F Checks member to the rules of EIA-222-F.


Reactions Reports tower reactions.Ancillary rotations Reports ancillary rotations.

Structure Menu Commands

STRUCTURE MENU

The Structure menu becomes active only when graphically inputting aUDP. It offers the following commands:

Command ActionDraw Members Draw members or input node coordinates.Erase Members Erase selected members.Select All Selects all members, including any that may not be

visible.Drawing Settings Snap modes for drawing members, grid spacing etc.Attributes Input attributes of the structure, such as restraints,

section numbers, etc.Move Move a node, move members, rotate members, stretch

nodes.Copy Linear copy, polar copy, reflect members.Sub-divide Sub-divide selected members into a number of equal

parts.Insert Node Insert a new node in a member.Intersect Insert new node(s) at intersection of selected members.Curve Sub-divide a member into a number of segments whose

ends lie on an arc.Arc/Helix Create members with ends lying on arc or helix.Renumber Renumber nodes and members (sort or compact).


Analyse Menu Commands

ANALYSE MENU

The Analyse menu offers the following commands:

Command ActionCheck Input Check structure and load data (normally automatic).Linear Perform linear analysis (first-order).Non-Linear Perform non-linear analysis (second-order).Elastic Critical Load Determine frame buckling load factors and buckling

mode shapes.Dynamic Determine natural frequencies and mode shapes.Response Spectrum Add response spectrum and static analysis results.

Results Menu Commands

RESULTS MENU

The Results menu offers the following commands:

Command ActionSelect Load Cases Select load cases for display of loads or results.Select Natural Modes Select modes for display of vibration mode shapes.Select Buckling Modes Select modes for display of buckling mode shapes.Undisplaced Shape Display structure in undisplaced position.Member Actions Display bending moment, shear force, axial force,


torque, or displaced shape.Natural Modes Display vibration mode shapes.Animate Modes Show each currently displayed mode (natural or

buckling) in alternate extreme positions. Press thespace bar to show the next mode, Esc to cancel.

Buckling Modes Display buckling mode shapes.Design Ratios Display results of member design check with colors

representing range of design ratios. The legend inthe Output window shows the range of valuesrepresented by each color.

Reports Menu Commands

REPORTS MENU

The Reports menu offers the following commands:

Command ActionInput/Analysis Create report on structure and current analysis results.

Show Menu Commands

SHOW MENU

The Show menu offers the following commands:

Command ActionSection Highlight members with specified section number.Material Highlight members with specified material number.


Member Type Highlight members of specified type (tension-only etc.).Nodes Highlight members connected to specified nodes.Members Highlight specified members.Master Nodes Show master nodes.Slave Nodes Show slave nodes.Node Masses Show all nodes with non-zero added mass.Design Members Show all defined design members.Cancel Cancel current “Show” selection.

Query Menu Commands

QUERY MENU

The Query menu offers the following commands:

Command ActionNode Data List data for selected node (coordinates etc.).Node Displacements List displacements for selected node.Support Reactions List reactions for selected (support) node.Master Node List slave nodes for selected master node.Slave Node List constraints for selected slave node.Member Data List member data for selected member.Member Displacements List displacements for selected member.Member Forces List member forces for selected member.Node Loads List loads for selected node.Member Loads List loads for selected member.Design Member Highlight design member containing selected

member.


Linear Ancillary List properties of linear ancillary.Large Ancillary List properties of large ancillary.Ancillary Group List properties of ancillary group.

Note: Query data is displayed in the Output window.

Window Menu Commands

WINDOW MENU

The Window menu offers the following commands, which enable you toarrange multiple views in the application window:

Command ActionCascade Arranges windows in an overlapped fashion.Tile Horizontally Arranges windows side-by-side.Tile Vertically Arranges windows above and below.Output Window Show or hide the Output window.Window All open windows are listed. Clicking one of these will

move the focus to the selected window.


Help Menu Commands

HELP MENU

The Help menu offers the following commands:

Command ActionMStower Help Topics Display the Help Topics dialog box. This has three

tabs, Contents, Index, and Find, so you can easilyfind help topics.

What’s This? Display help for clicked buttons, menus, andwindows.

Tip of the Day Show Tip of the Day.About MStower Display details about this copy of MStower and

system resources. Also contains links to Internet.

Main Toolbar Commands

MAIN TOOLBAR

The Main toolbar offers the following commands:• Open a new job.• Open an existing job. MStower displays the Open dialog box, in

which you can locate and open the desired file. This command is foropening an existing job – one for which there is already a Job.MSTfile, where “Job” is the name of the job as it was saved.

• Save the job with its current name.• Print the view; i.e. print a picture showing the current view of the

structure. Use the File > Print command to print a file.• Print preview; i.e. display exactly how the graphics will be printed.

Use the File > Preview command to preview a file.


View Toolbar Commands

VIEW TOOLBAR

The View toolbar offers the following commands:• Display front view.• Display right view.• Display top view.• Display oblique view.• Move viewpoint to left.• Move viewpoint to right.• Move viewpoint up.• Move viewpoint down.• Zoom to extents/limits of structure. If the View > Limit command is

in effect, clicking this button alternately displays the full structureand the limited part of the structure.

• Zoom in.• Zoom out.• Zoom to selected window.• Pan.• Show the Output window.


Display Toolbar Commands

DISPLAY TOOLBAR

The Display toolbar offers the following commands:• Display node symbols.• Display of node numbers.• Display member numbers.• Display section numbers.• Display supports.• Display pins.• Display rendered view of members.• Display annotation of loads.• Display annotation of member force or displacement diagrams.• Increase scale for plotting loads, member forces, or displaced shape.• Decrease scale for plotting loads, member forces, or displaced

shape.

Help Toolbar Commands

HELP TOOLBAR

The Help toolbar offers the following commands:• Context (“What’s This?”) help. The cursor changes to a pointer with

a question mark that may be clicked on any toolbar button toprovide a pop-up help window.

• Help About MStower. MStower version and configuration details –includes links to Internet.


Draw Toolbar Commands

DRAW TOOLBAR

The Draw toolbar is available during graphical input of UDPs only. Itoffers the following commands:• Draw members.• Erase members.• Move members.• Copy members.• Reflect members.• Sub-divide members.• Rotate members.• Display grid points and set Grid snap mode.• Set Middle/End snap mode.• Set Intersection snap mode.

Attributes Toolbar Commands

ATTRIBUTES TOOLBAR

The Attributes toolbar offers the following commands:• Input section numbers.• Input member releases.• Input member orientation reference node/axis.


Results Toolbar Commands

RESULTS TOOLBAR

The Results toolbar offers the following commands:• Display undisplaced structure.• Select load cases for display.• Display applied loads.• Display member actions. You must turn on this “switch” before you

are able to select member forces for display.• Display axial force, Fx.• Display shear force, Fy.• Display shear force, Fz.• Display torque, Mx.• Display bending moment, My.• Display bending moment, Mz.• Display displaced structure.• Display natural vibration modes.• Display buckling modes.• Display design ratios. Design ratios are displayed graphically with

different colors representing distinct ranges of values for thepercentage of code capacity. For example, members shown brightred are loaded in excess of 110% of the design code capacity.

• Display member force envelope.• Animate modes (natural or buckling). Each mode is displayed in

turn. Press the space bar to move to the next mode or Escape to exitmode animation.

OK/Cancel Toolbar Commands

OK/CANCEL TOOLBAR

The OK/Cancel toolbar is an alternative to the context menu forconfirming or cancelling selections. Display or hide it with the View >Toolbars command. This toolbar is not displayed initially.


Extra Buttons Toolbar Commands

EXTRA BUTTONS TOOLBAR

The Extra Buttons toolbar contains a number of buttons that may beadded to other toolbars during customization. It is not displayed initially.The buttons available are:• Display back view.• Display left view.• Display y axis for all members.• Polar copy.• Intersect members.• Insert node.• Redraw (F5).

Selecting Which Toolbars Are DisplayedYou may easily determine the toolbars that are displayed with the View> Toolbars command. This displays the dialog box shown below. Allchecked toolbars are displayed.

TOOLBARS DIALOG BOX

You may also choose the new flat style for toolbars (the “cool” look) orlarge buttons (these may be preferable at high screen resolutions). Anytoolbar that has been customized may be reset to the originalconfiguration by selecting it and then clicking the Reset button.


Customizing ToolbarsAs well as being dockable, toolbars in MStower are customizable in twoways.Firstly, while pressing the Alt key you may drag any button to anyposition on the same or another toolbar. If you drag a button to a newposition not on a toolbar, it will disappear.Secondly, you may click the Customize button in the Toolbars dialogbox (View > Toolbars command). This displays the Customize propertysheet. Clicking the New button creates a new empty toolbar with anyspecified name. On the Commands tab you may now select any existingtoolbar and drag its buttons onto the new toolbar (or any other toolbar).

CUSTOMIZING TOOLBARS

The Ouput WindowThe Output window, normally at the bottom of the main window, isdockable. You may click on any part of the edge of the Output windowand drag it, so that it floats inside the main window or docks on any edgeof the main window. You may double-click on the title bar of the floatingOutput window and it will return to its previous docked position. Clickthe Output Window button to hide or display the Output window.

MSTower V5 4:Operation • 33

4:Operation

Data FilesThe tower is described in data files by the minimum number of keydimensions and a description of the types of panel in the tower. Paneltypes are described by mnemonics of one to four characters. Panels maybe selected from a set of built-in face, plan, hip, and cross-arm patternsor may be defined by the user.The following data files are used:• Job.TD

The tower data file.• Job.UDP

An optional file containing the description of non-standard or user-defined panels.

• Job.TWRThe tower loading file.

It may be convenient to copy the data files from an existing MStower joband edit these, rather than creating them from the beginning. This maybe done by opening the existing job and selecting the File > Save CopyAs command to create the new job.The data files are text files, usually created and edited with the built-intext editor, MsEdit. Data is set out in blocks identified by keywords.Blank lines may be used as required to improve the readability of thefile. The “$” character may be used to introduce comments; the “$”character and all text following on that line are ignored as input data.Individual items of data may be separated by one or more blank spaces.Each line of data must be no longer than 80 characters.

34 • 4:Operation MSTower V5

The following conventions are used to describe the input data:Square brackets are used to indicate optional data items. A and B maybe omitted in this example:...[ A ] [ B ]...

Braces are used to indicate where a choice must be made from a list ofitems. Items may be shown vertically, or horizontally when separated byvertical bars. For example:...{ item 1 }...

{ item 2 }{ item 3 }

or...{ item 1 | item 2 | item3 }...

One of the items must be chosen. An ellipsis indicates that the data description in this manual is continuedon the next line. Unless otherwise noted, the data in the file must be onone line.The “&” character at the end of a line indicates that the data continues onthe next line.

Note: Parentheses, braces, and ellipses do not appear in the tower datafiles.

UnitsMStower accepts two sets of units:• Metric – using meters, kilonewtons, tonnes, and degrees Celsius,

with some data items being input and/or reported in the morecustomary units of mm and kg.

• US – using feet, kips, kip.sec2/ft, and degrees Fahrenheit, with somedata items being input and/or reported in the more customary unitsof inches and pounds.

Entries in the ancillary and guy libraries are required in metric units.

AxesThe vertical axis of the tower is parallel to the global Z axis. The X andY axis of the tower lie in the horizontal plane and do not need to bealigned with the geographic north. The X axis is always normal (in plan)to one face of the tower.

SectionsAll sections in the tower must be described in an MStower sectionlibrary file. Dimensions and properties are automatically extracted tocompute surface and projected areas when calculating ice and wind loadsand for determining member capacities.

MSTower V5 4:Operation • 35

Member CheckingYou must ensure that wind velocities and other factors used to computeloads are consistent with the code method chosen to check memberstrengths.BS 8100:Part 3, AS 3995, and ASCE10-90 are limit states codes,whereas BS 449 and EIA/TIA-222-F use permissible stresses.

ErrorsAfter assembly of the tower, MStower checks for the followingconditions:Overlaid Members And Unconnected NodesThese occur when a node is coincident with a member but not connectedto it. When this occurs it is usually at the junction between panels andhappens either because a horizontal has not been deleted or because ofan incompatibility between panels. For example if a PL1 plan brace isused with an X face brace the PB1 member will overlay the H1 member.The duplicated member will not be detected by the assembly processbecause of the mid-side node in PB1. A list of such members will bedisplayed.Floating MembersThese are members that are not connected to the structure. If notremoved they will result in errors during analysis. They can result ifmembers are deleted; for example if PL1 plan bracing is used with XOface bracing and the PB1 member is deleted, the internal plan bracingmembers will not be connected to the tower. A list of such members willbe displayed.You may readily locate overlaid and floating members using MStowerscreen plots. Select the Show > Members command and then enter thelist of offending members. The full tower will now be displayed with thelisted members highlighted. You may zoom to inspect the membersmore closely and determine the reason for the error. The TD or UDP fileshould be modified as necessary.Section ChecksThe tower builder does a number of sensibility checks as the tower isassembled and reports on the following:• Section usage – whether the section is used as a leg, brace, or other

type of member.• Whether the connection code is appropriate to the section type.• Whether a bolt-hole width has been specified for bolted members.

There are also preliminary range checks on the magnitude.You may inspect the above reports by clicking the Build tab on theOutput window.

36 • 4:Operation MSTower V5

MSTower V5 5:Tower Data • 37

5:Tower Data

GeneralData describing the tower geometry is entered into a free-format text filecalled Job.TD, where “Job” is the job name. A prototype tower data filemay be generated by selecting the Tower > Build Tower > MakeTower Data File command. The dialog box shown below appears foryou to enter the basic geometric parameters.

GEOMETRY PARAMETERS DIALOG BOX

You may then enter details for each panel in this dialog box.

PANEL DETAILS DIALOG BOX

The resulting tower data file is shown below. It must now be customizedfor the particular tower you are modelling. The file will be displayed inthe MsEdit text editor when you select the File > List/Edit Filecommand and then choose “TD”.

38 • 5:Tower Data MSTower V5

TITL1 Test towerTITL2UNITS 1

PROFILEFACES 4WBASE 4.0000RLBAS 0.0000

PANEL 1 HT 1.000 TW 1.000FACE X $ LEG ? BR1 ? H1 ?




END

SECTIONSLIBR P:UK IFACT 0.1 $ 1.001 EA200X200X162 EA150X150X103 EA100X100X84 EA70X70X6

END

BOLTDATA$ TODO - bolt data goes here - format of bolt data:$ [ X x Y y Z z NSP nsp LJ lj ]

END

END

PROTOTYPE TOWER DATA FILE

The Tower Data (TD) FileThe tower data file is organized into logical blocks:1. Title block.2. Component block.3. Profile block.4. Supports block.5. Guys block.6. Sections block.7. Material block.8. Bolts block.


Each block commences with a keyword identifying the block andterminates with the keyword END. The keyword EOF is used toterminate the file. Each data block is described in this chapter.

Title BlockTITL1 titl1TITL2 titl2UNITS units

where:TITL1 Keyword.titl1 First line of job title.TITL2 Keyword.titl2 Second line of job title.UNITS Keyword.units Integer value indicating system of units being used – 1 or 4.

1 = SI units.4 = US units.

Component BlockAlthough MStower provides a comprehensive range of panel types, theremay be times when you wish to define additional panel types. This blockallows you to reference a file containing panel data to be included in thetower.COMPONENT

udp file...

END

where:udp Name (1-8 characters) of a user-defined panel.file Name of file containing the data for the user-defined panel. The

file may contain more than on user-defined panel. It isrecommended that the UDP file have the same name as the job.It must have the file name extension “UDP”.


Profile BlockThis block provides the data used to generate the node coordinates andmember connectivity of the tower. Panels are described in order, fromthe top of the tower.The block contains descriptions of the face bracing, plan bracing, hipbracing, and cross-arms. Section property numbers may be assigned tothe various types of members in each panel; the property number for amember type need not be specified again unless there is a change. Panelwidths need to be input only at the bend points; intermediate widths willthen be interpolated automatically.PROFILE

FACES nfaceWBASE wbaseRLBAS rlbas

PANEL nn HT hpanl [TW bpanl] [scale]BOLT class nbolt [bolt_id] class nbolt [bolt_id]...FACE ftype [SPACE s1 ... ns @ sm ... sn]...

[F1 f1 F2 f2]...[NTR ntr] [ND nd] [NPL npl]...[D] [INV] [LEFT]...[LEG leg BR1 br1 BR2 br2 BR3 br3...H1 h1 H2 h2 R1 r1 ... R9 r9]...[LA la] [LB lb] [LC lc] [LD ld]

PLAN ptype [PB1 pb1 PB2 pb2 PB3 pb3 ...]...[F1 f1 F2 f2] [locn]

HIP htype [NTR ntr] [ND nd] [HP1 hp1] [HP2 hp2]CROSS ctype [X | Y] [SPAN span] | [SL sl | SR sr]...

[RL rl] [RR rr] [CR1 cr1 CR2 cr2 ...]

PANEL ...

END

where:FACES Keyword.nface Number of faces in the tower, either 3 or 4.WBASE Keyword.wbase Base width of tower; i.e., the base width of the lowest panel.RLBAS Keyword.rlbas RL at tower base with respect to the ground level at the site.

The nodes at the bottom of the legs will have this value as theirZ coordinate.

PANEL Keyword.nn Panel number.HT Keyword.hpanl Panel height.TW Keyword.

bpanl Width at top of panel. If not given, this value will beinterpolated.


scale Optional keyword pertaining to variable dimensions F1 and F2:FR F1 and F2 are factors; the actual dimensions are obtained bymultiplying a length as shown on the panel diagram.LE F1 and F2 are lengths.

If omitted, fractional scaling, FR is assumed.

BOLT Keyword.class Member class, one of the following member types:

LEG Leg members.BR BR1..BR3 Bracing in the face.H H1 H2 Horizontal in the face.R R1..R9 Face redundant.PB PB1..PB10 Plan bracing.HP HP1..HP10 Hip bracing.CR CR1..CR10 Cross-arm members.If a mnemonic without a numeric suffix is used, all members ofthe class will have the number of bolts specified.

nbolt The number of bolts in the end connection of the member.You may use as many class/nbolt pairs as are necessary.

bolt_id Optional character string, used to identify the bolt in theBOLTDATA table.

FACE Keyword.ftype Face bracing pattern type. User-defined panels must have their

names prefixed with the “@” character; e.g. @XYZ refers to auser-defined panel XYZ. UDPs may have names with amaximum of 8 characters and must have been referenced in theCOMPONENT block.

SPACE Keyword.s1..sn List of spacings for XM, DM DLM, DRM ,DMH, KXM and

XDM type face bracing.ns @ sm Shorthand way of indicating that a multiple panel has a number

of identical spacings:ns Number of identical spacings.@ Keyword.sm


Value of identical spacing.F1,F2 Keywords.f1,f2 Factors used to locate nodes for some bracing types.NTR,ND Keywords.ntr,nd Number of levels of triangle and diagonal braces, respectively,

in some face and hip brace patterns.NPL Keyword.npl Bracing pattern in part of a portal or cranked K face.D Keyword – used with XDM bracing.LEFT Keyword – used with DM bracing.INV Keyword, used with KB, KBP, KM, KMA, KMG, KMGA,

KMGD, KMH, KMHA, KMV, KVH3, and KVS3, indicatingthat the panel is to be inverted.

LEG Keyword.leg Section property number for leg members.BRn Keyword.brn Section property number for brace members, type n, where n is

a digit from 1 to 3.Hn Keyword.hn Section property number for horizontal members, type n, where

n is a digit from 1 to 2.

Rn Keyword.rn Section property number for redundant or secondary bracing

members, type n, where n is a digit from 1 to 9.All property numbers for a particular member class may be setby using the keyword without a numeric suffix; e.g. BR will setBR1, BR2, and BR3.

LA,LB,LC,LD

Keywords.

la,lb,lc,ld

Section property numbers for leg A, B, C, and D, respectively.Leg A is in the positive X-Y quadrant and the other legs areidentified in sequence, anti-clockwise from leg A when viewedin plan. The properties of the leg members of the tower may beassigned individually if they are not symmetrical. In any case, anon-zero property must follow the LEG keyword.

PLAN Keyword.ptype Plan bracing pattern type.PBn Keyword.pbn Section property number for plan bracing member, type n,

where n is a value from 1 to 10. The property numbers for allplan braces will be set to this value if the numeric suffix is


omitted from the keyword.F1,F2 Keywords.f1,f2 Factors used to locate nodes for some bracing types.locn Optional character string indicating the vertical location of plan

bracing in the current panel. If omitted, the plan bracing will beplaced at the top of the face panel. Must be one of:TOP Top of the face panel.BTM Bottom of the face panel. This may be required with certaininverted face panels or type “M” face bracing.XIP The level of the intersection of cross-brace members in theface.MID The mid-height of the face.

CROSS Keyword.ctype Cross-bracing pattern type.X,Y Keywords indicating that the cross-arms are to be attached to

the X or Y faces of the tower. If not specified the cross-armswill be attached to the Y faces; i.e. they will project to the leftand right when viewed from the direction of the X axis.

SPAN Keyword.span Total span of symmetrical cross-arm. If the cross-arm is not

symmetrical, separate left-hand and right-hand “half” spansmust be specified.

SL Keyword.sl Left-hand “half” span of the cross-arm. Viewed from the

positive X axis direction if attached to the Y faces, or viewedfrom the positive Y axis direction if attached to the X faces.

SR Keyword.sr Right-hand “half” span of the cross-arm.RL Keyword.rl Rise of left-hand “half” span of the cross-arm when viewed as

described above.RR Keyword.rr Rise of right-hand “half” span of the cross-arm.CRn Keyword.crn Section property number for cross-arm member, type n, where

n is a value from 1 to 10. The property numbers for all cross-arm members will be set to this value if the numeric suffix isomitted from the keyword.


If a mnemonic without a numeric suffix is used, all members of the classwill have the number of bolts specified. Bracing patterns and the locationof different member types are shown on the bracing diagrams. Some facepanels, such as XTR and KTR, are shown with asymmetrical redundants.In these cases, the arrangement of redundants on the left-hand part of thediagram applies to the X faces of the tower while that on the right-handside applies to the Y faces.

Note: The number of bolts in the ends of members is used in strengthchecking modules to determine buckling curves or effective slendernessratios. If the number of bolts is not specified MStower will assume thatall members are single-bolted except for legs, face bracing, andhorizontals that are assumed to have two or more bolts. Normally, thebolt specification will be entered in the first panel; it is only necessary toenter changes (if any) in subsequent panels. The bolts themselves willnot be checked unless bolt_ids are defined in BOLT statements andbolt information is defined in a BOLTDATA block.

Only one set of face, plan, and hip bracing may be specified for anypanel. Up to two sets of cross-arms may be specified in a panel to allowpanels at the top of power transmission towers where twin earth peaksoccur with normal cross-arms.Redundant members are pin-ended. All other members are assumed tobe rigidly connected.Any member assigned a property number of zero will be deleted. Forexample an “X” face panel with H1 = 0 is identical to an “X0” panel.You must ensure that the deletion of members does not result in anunstable structure.When inverting panels, it may be necessary to delete the horizontalmember in either the inverted panel or the panel on which it is mounted,if the two horizontals are not sub-divided in identical fashion.“C” nodes, which define member orientation, are allocated in the planeof the face or hip for all members except H1 and H2 type members,where the “C” node is in the direction of the global “Z” axis; i.e. for facemembers apart from H1 and H2, and hip braces, the member “y” axislies in the plane of the hip or face. Orientation keywords may be appliedto the section definition (see “Sections Block”, below) if the section is tobe rotated.


The example below shows the TD file statements required to generate apyramidal face panel with two sets of cross-arms.

PANEL 1 HT 1.372 TW 0

FACE X0 LEG 1 H1 0 BR1 0CROSS CT SPAN 6 RISE 7 CR1 10 CR2 12CROSS CT SPAN 8

PANEL 2 HT 3.13 TW 1.6FACE XDM SPACE .788 .787 .788 .787 D LEG 1 H1 2 BR1 2

PANEL 3 HT 1.575FACE XDM SPACE .788 .787 DCROSS CT1 SPAN 8.32 CR1 10 CR2 12 CR3 15 CR4 16

PANEL EXAMPLE

Plan bracing is located as shown in the diagram below.

LOCATION OF PLAN BRACING


Supports BlockThis block is optional and may be used to modify the default supportconditions of full fixity for all supports except for masts where the legsjoin at a single pinned support point.SUPPORTS

{COORD x y z | LEG abcd} ...{PINNED|FIXED [BUT {releases|springs}]}...

END

where:COORD Keyword.x y z Coordinates of a node that is to be restrained.LEG Keyword.abcd Leg number in the form of a compact list using the characters

A, B, C, or D. Leg A is in the positive X-Y quadrant. The otherlegs are identified in sequence, anti-clockwise from leg A whenviewed in plan; e.g. AC would indicate that the supportconditions apply to legs A and C.

PINNED Keyword indicating that the node is pinned; i.e., it is free torotate but all translational degrees of freedom are restrained.

FIXED Keyword indicating that the node is completely fixed; i.e., alldegrees of freedom are restrained.

BUT Keyword used with FIXED to indicate that some degrees offreedom are to be released or have spring restraints.

releases List of degrees of freedom to be released. One or more of:FX FY FZ MX MY MZ

springs List of degrees of freedom that are to be restrained by springs,with the corresponding spring constant. One or more of thefollowing pairs:KFX kfx KFY kfy KFZ kfz KMX kmxKMY kmy KMZ kmz


Guys BlockThis block pertains to guyed masts only and is used to specify the librarycontaining the properties of guy wires and their arrangement on the mast.GUYS

LIB libXB xb YB yb ZB zb XT xt YT yt Zt zt NO no ANGL angl...TO to KT kt LIB guy_id

END

where:LIB Keyword.lib Name of library containing guy data. It is assumed that the

library is located in the data folder unless the name is prefixedwith “P:” or “L:”. “P:” indicates that the library is in theprogram folder and “L:” indicates that it is in the library folder.

XB Keyword.xb Global X coordinate of the lower end of the guy.YB Keyword.yb Global Y coordinate of the lower end of the guy.ZB Keyword.zb Global Z coordinate of the lower end of the guy.XT Keyword.xb Global X coordinate of the upper end of the guy.YT Keyword.yb Global Y coordinate of the upper end of the guy.ZT Keyword.zb Global Z coordinate of the upper end of the guy.NO Keyword.no Number of guys in this group.ANGL Keyword.angl Angle between successive guys in the group, in degrees.TO Keyword.to Initial guy tension, in kN or kips. The unstrained length of the

guy will be adjusted so that when stretched between theundisplaced end nodes, the maximum tension in the guy willequal this value. The still air tension will be less than the initialtension due to the elastic shortening of the shaft of the mast.

KT Keyword.kt Guy connection efficiency factor.LIB Keyword.guy_id Character string of 1 to 16 characters used to identify the guy in

the guy library. The properties of the guy required for analysisand design will be taken from the guy library.


The first guy in the group will span between (xb, yb, zb) and (xt, yt, zt),and if no is greater than 1, additional cables will be automaticallygenerated at an angular increment of angl anti-clockwise about thevertical axis of the mast. Guys can be generated only where they areradially symmetrical about the vertical axis of the mast. For example,guys that have their anchor points at different levels because of a slopingsite have to be input singly.Usually, guys are input as single members. A guy may also be input as anumber of segments to accommodate changes in properties or to allowan insulator to be positioned along its length. In this case, you shouldinput the segments of guy sequentially, commencing at the anchor pointand working up to the mast shaft with the coordinates of the lower endof one segment being set equal to those of the upper end of the precedingsegment. The segments of guy may be generated as described above.

Sections BlockThis block specifies the section library and nominates the section to beused for each section property number.SECTIONS

LIBR libr IFACT factn sname [X|Y] [CONNECT con] [BH bh] [FY fy]...

END

where:LIBR Keyword.libr Name of library containing section data. It is assumed that the

library is located in the data folder unless the name is prefixedwith “P:” or “L:”. “P:” indicates that the library is in theprogram folder and “L:” indicates that it is in the library folder.

IFACT Keyword.fact Factor by which the section Ixx and Iyy will be multiplied on

extraction from the library. When you specify a low value thetower will approach the condition of a space truss with pin-ended members. This is convenient for analysing as a spaceframe, with sufficient continuity across the joints to avoidmathematical instabilities due to coplanar nodes, but withoutgenerating significant bending moments.

n Section property number.sname Name of library section.X Y Keywords used to indicate the orientation of the section with

respect to the member y axis:X The section XX axis is aligned with the member y axis.Y The section YY axis is aligned with the member y axis.Use of these keywords will allow you to correctly orientasymmetrical sections. For example, if an unequal angle is usedin the face of the tower, orientation Y will result in the long leg


of the angle being parallel to the face, whereas orientation Xwill result in the long leg being normal to the face of the tower.Note that the member y axis is not altered by the use of anorientation keyword. See diagram below.

CONNECT Keyword.con Single-character mnemonic indicating the connected element of

the section:C Concentrically connected (default).L Long leg of angle.S Short leg of angle.F Flange of I, H, or T section.W Web of I, H, or T section.It is important that you specify the connected element for eachsection. If omitted, MStower assumes the member isconcentrically connected, giving a higher strength than it mayactually have.

BH Keyword.bh Effective width of bolt holes, in mm or inches, in the connected

element, taking into account any staggering of holes,FY Keyword.fy Yield stress of the section. It may be either a numerical value,

in N/mm2 (MPa) or Kips/in2, or, a single-character mnemonicindicating the yield strength to be taken from the sectionlibrary:N Normal yield stress (default).H High yield stress.

N and H yield strengths correspond to the “y1” and “y2” yieldstrengths in the MStower section libraries. In UK libraries,these will normally be based on Grade 43 and Grade 50 steel,respectively.

The orientation of the section is the cross-section axis (XX or YY) that iscoincident with the member y axis (see diagram below).

ORIENTATION OF SECTION


Compound Angle SectionsThe MStower section library will accept compound angle sections.The compound section types most commonly found in towers andsuggested mnemonics are:Type 11: DAL – Double angles, long legs together.Type 12: DAS – Double angles, short legs together.Type 16: STA – Double angles, starred or cruciform.Type 22: QAN – Four angles, cruciform.These are shown in the diagram below.

COMPOUND ANGLES

The data to be entered in the section library source file (Lib.ASC, where“Lib” is the library name) is as follows:

$ Properties of compound section Component dimensions$ <-------------------------------> <-------------->$ A Ax Ay J Ix Iy Rx Ry Zx Sx Sy M D B t g sp rv f y1 y2

S 11 DAL200x100x10 0 0 0 0 0 0 0 0 0 0 0 0 200 100 10 10 600 0 0 275 365S 12 DAS200x100x10 0 0 0 0 0 0 0 0 0 0 0 0 200 100 10 10 600 0 0 275 365S 16 STA100x100x12 0 0 0 0 0 0 0 0 0 0 0 0 100 100 12 10 500 0 0 275 365S 22 QAN100x100x12 0 0 0 0 0 0 0 0 0 0 0 0 100 100 12 10 500 0 0 275 365


The properties, A Ax...M are those of the compound section. Anyproperties with zero values, as shown above, are computed automaticallyfrom the dimensions of the component angles neglecting any toe androot radii.Component dimensions and properties are as follows:

D Length of the vertical leg of the angle (parallel to the sectionYY axis) – the long leg for unequal angles.

B Length of the horizontal leg of the angle (parallel to the sectionXX axis) – the short leg for unequal angles.

t Thickness of the angle.g Gap between the component angles.sp Stitch bolt or packer spacing. 0 = continuously connected.rv Minimum radius of gyration of the component angle.f Reserved, currently zero.Y1 Normal yield stress (N).Y2 High yield stress (H).

Units, which vary from library to library, are specified on the second lineof the library source file. Section dimensions and geometric propertiesare normally in mm or inch units. However, in some UK libraries,derived properties may be in the more customary cm units.When adding to a library, it is recommended that you follow a similarnaming convention to that used by a similar section already in theparticular library. The section name must not exceed 15 characters inlength and the alphabetic mnemonic, which may be anywhere in thename, should not be longer than 4 characters. For example,“DAS200x100x10”, “EA4.5x4.5x5/16”, “65x65x5.0SHS”, and“180UB16.1” are permissible sections names.

Material BlockThis block is optional. It is used to change the default values of thematerial used for the tower or the shaft of a mast.MATERIAL

E e PR pr DENS dens ALPHA alphaEND

where:E Keyword.e Young’s modulus (2.05E5 N/mm2 or 29000 kips/in2).PR Keyword.pr Poisson’s ratio (0.3).DENS Keyword.


dens Mass density (7850 kg/m3 or 490 lb/ft3).ALPHA Keyword.alpha Coefficient of thermal expansion (12.0E-6 per °C or 5.9E-6 per

°F).

The default material properties are shown above in brackets.

Note: Material properties for guys are obtained from the specified guylibrary.

Bolt Data BlockThis block specifies bolt diameters, grades, and other data required inchecking the capacity of bolted end connections.BOLTDATA

bolt_id grade D d AS as FY fy FU fu FV fv ...FV_EIA fv_eia FV_ASCE fv_asce ...[X x] [Y y] [Zz z] [NSP nsp] [LJ lj]

...END

where:E Keyword.bolt_id String of 1 to 8 characters used to identify the bolt type in the

BOLT statement in the PANEL data above.D Keyword.d Nominal bolt diameter, in mm or inches.AS Keyword.as Cross-sectional area of the bolt effective in shear, in mm2 or

in2.FY Keyword.fy Yield stress of bolt, in N/mm2 (MPa) or kips/in2.FU Keyword.fu Ultimate tensile stress of bolt, in N/mm2 (MPa) or kips/in2.FV Keyword.fv Shear strength of bolt, in N/mm2 (MPa) or kips/in2, used when

checking bolts to AS 3995; capacities to this code are strengthlimit state.

FV_EIA Keyword.fv_eia Shear strength of bolt, in N/mm2 (MPa) or kips/in2, used when

checking the capacity of bolted joints to EIA-222-F; capacitiesto this code are based on working stress.

FV_ASCE Keyword.


fv_asce Shear strength of bolt, in N/mm2 (MPa) or kips/in2, used whenchecking the capacity of bolted joints to ASCE 10-90;capacities to this code are strength limit state.

X Keyword.x Distance between end of the member and first bolt parallel to

the axis of the member, in mm or in. If omitted, the memberchecking program assumes that code requirements are met.

Y Keyword.y Distance between line of bolts and edge of member at right

angles to the axis of the member, in mm or in. If omitted, themember checking program assumes that code requirements aremet.

Z Keyword.z Spacing between bolts parallel to the axis of the member, in

mm or in. If omitted, the member checking program assumesthat code requirements are met..

NSP Keyword.nsp Number of shear planes. This value needs to be specified only

if the number of shear planes in the bolted joint differs from thedefault values used in the member checking modules. Bolts areassumed to have a single shear plane for all sections exceptcompound sections, DAL, DAS, CBB, and QAN, where thebolts are in double shear.

LJ Keyword.lj Length of the line of bolts in the joint, in mm or in. This value

is required only for codes that reduce the strength of longjoints. If omitted, the strength will not be reduced.

Bolted joint capacities can be checked only in conjunction with amember check. This has been implemented for all codes other thanBS 449.A bolt data file called Bolts is included in the program folder. You maycopy its contents to TD files using Copy and Paste commands in MsEdit.


Guy LibraryThe guy library is a text file containing data giving the dimensions andstructural characteristics of wire ropes used as guys. The library may bemodified if required.The structure of the guy library file is:GUYS

guy-id d m ac e alpha fu ntype...

END

where:GUYS Keyword.guy-id String of 1 to 16 characters used to identify the guy ropes.d Diameter of guy rope, mm.m Mass per unit length, kg/m.ac Effective cross-sectional area, mm2.e Modulus of elasticity, N/mm2.alpha Coefficient of thermal expansion, per °C.fu Ultimate tensile stress, N/mm2.ntype Guy type, based on Table 4.1 of BS 8100:Part 4:

1. T4.1(b) Circular sections and smooth wire.2. T4.1(c) Fine stranded cable.3. T4.1(d) Thick stranded cable.

Note: The guy library uses metric units.

MSTower V5 6:Standard Panels • 55

6:Standard Panels

The following pages show the standard panels available in MStower.

56 • 6:Standard Panels MSTower V5

Index – Face Panels





Index – Plan Bracing


Index – Hip Bracing & Cross-Arms


D & V Face Panels


X Face Panels





K Face Panels









M Face Panels



W Face Panels


XMA Face Panel


DM Face Panel


DMH Face Panel


DLM & DRM Face Panels


KXM Face Panel


XDMA Face Panel


Plan Bracing





Hip Bracing



Cross-Arms

MSTower V5 7:User-Defined Panels • 91

7:User-Defined Panels

GeneralWhile MStower has an extensive set of standard panels, there will betimes when some variant will be required to model a particular panel.MStower allows you to create your own panels – user-defined panels, orUDPs, for just this purpose. Unlike standard panels, which are scaled tothe dimensions specified in the tower data file, UDPs once created are offixed size.Although data for the UDP is contained in a text file which may beedited, the most expeditious way of creating a UDP is to start bybuilding a tower with standard panels that are as close to the finalconfiguration as possible, and then to extract and graphically edit a panelas required. MStower has facilities (see “8:Graphics Input for UDPs” onpage 99) that allow UDPs to be created and manipulated using a CAD-like interface. For most UDPs you will never need to edit the text file.

92 • 7:User-Defined Panels MSTower V5

The UDP FileData for user-defined panels must be included in one or more separateUDP files. The file names are specified in the COMPONENT block of thetower data file. The data may represent a full face, a half face, a quarterof a section of the tower, a pair of adjacent faces, or a complete threedimensional section of the tower, depending on which is mostconvenient for describing the panel. MStower will generate the completepanel. The data for the user-defined panel is:UDP udp HT ht TW tw BW bw

{PLANE | HALF | QUART | ADJA | 3DIM}NODEn x y z...MEMBm ia ib ic mp mm pina pinb code...

END

where:UDP Keyword.udp Name of user-defined panel as used in the COMPONENT block

of the tower data file..HT Keyword.ht Height of panel. This should be the height of the panel between

its points of attachment to the panels above and below. It is notnecessarily the maximum overall height of the panel.

TW Keyword.tw Top width of the panel; i.e. the width of the panel at the level at

which it attaches to the panel above. If not given, the width ofthe tower at this level will be interpolated.

BW Keyword.bw Base width of the panel; i.e. the width of the panel at the level

at which it attaches to the panel below. If not given, the widthof the tower at this level will be interpolated.

PLANE Keyword indicating that the data applies to a plane face that isto be used to generate a full face panel. The panel lies in the Y-Z plane with all X coordinates zero.

HALF Keyword indicating that the data applies to half a plane facelying in the YZ plane with all X coordinates zero.

QUART Keyword indicating that the data applies to two adjacent halfpanels disposed about the leg in the positive X and negative Yquadrant.

ADJA Keyword indicating that the data applies to two adjacent faces.This is used for panels where the adjacent faces differ. Thepositive X and positive Y faces should be defined.

3DIM Keyword indicating that the data applies to a full three-dimensional section of the tower.


NODE Keyword.n Node number.x X coordinate of node.y Y coordinate of node.z Z coordinate of node. The points of attachment to the panel

immediately below should have Z coordinates of zero.MEMB Keyword.m Member number.ia Node number of the “A” end of the member.ib Node number of the “B” end of the member.ic Reference or “C” node. Face members, such as legs and braces,

should have a node in the plane of the face as their referencenode. This is of particular importance for legs that havestaggered face bracing and for face braces such as unequalangles that must have a particular orientation.

mp Section property number. The section must be defined in theSECTIONS block of the TD file.

mm Material number, usually 1.pina Pin code for “A” end of member, a six character string of 0s

and 1s. From the left, 1s represent force releases for Fx, Fy, Fz,Mx, My, and Mz, respectively.

pinb Pin code for “B” end of member.code Member type code:

LEG Leg member.BRC Brace member, other than XBR or KBR.XBR X brace, symmetrically braced.KBR K brace, symmetrically braced.HOR Horizontal member.HBR Hip brace.PBR Plan brace. This code applies only to the internalmembers of plan bracing. Any plan brace member in the face ofthe tower must be classified as HOR.RED Redundant member.CRM Cross-arm main memberTBR Tension only bracing.

The dimensions of the UDP are taken from its coordinates. The heightand panel widths are used to locate the UDP in the tower and to allowany standard panels that are above or below the UDP to be correctlyscaled. Unlike standard panels, user-defined panels cannot be scaled.


UDPs


UDPs


Making A UDP Using Graphics InputThe simplest way to make a UDP is to generate a tower using standardpanels that are close in configuration to the required panel, and then touse graphical input to extract the panel and make any necessarymodifications. MStower has commands to convert this to a UDP, but thecomponent references must be put into the tower data (TD) file using theeditor.To use this module effectively you must use the Structure > Attributes> Material Number command to set the material number for membersas follows:

LEG 100 Leg members.BRC 200 Bracing, other than X braces or K braces.XBR 300 X braces.KBR 400 K braces.HOR 500 Horizontals (redundants).HBR 600 Hip braces.HST 700 Hip stays.PBR 800 Plan braces.RED 900 Redundant or secondary members.CRM 1100 Main members of cross-arms.TBR 1200 Tension-only bracing (requires non-linear analysis).

During the conversion to a UDP the material number of a member isused to determine its class. The material number in the UDP will be setto the units value of the material number (or 1 if this is zero). The nameof the UDP and its type (PLANE, HALF etc.) will be requested. The HT,TW, and BW will be filled in but should be checked, particularly in thecase of cross-arms.If the UDP contains leg members, the HT, TW, and BW values will bedetermined by examining the coordinates of those nodes that are on legs.The Z coordinates of all nodes will be adjusted so that the lowest “legnode” has a Z coordinate of zero. If the UDP does not contain legmembers, the HT value will be set to zero and no adjustment will bemade to the Z coordinates.


UDP ExampleBelow is a step-by-step procedure for making a UDP:

Step 1 – Create TowerCreate a tower (using panels similar to those required) using theTower >Build Tower > Make Tower Data File command.

MAKE TOWER DATA FILE COMMAND

List all the sections required at the bottom of the tower data file.Display the tower looking along either the X or Y axis and select theTower > Build Tower > User-defined Panels > Graphical Editcommand. This will enable the menu items that allow graphical editingand input.

Step 2 – Erase MembersSelect the Structure > Erase Members command. Delete all the towerexcept the panel you wish to use as a template. You may drag a selectionbox to select groups of members or pick individual members. Note thatbottom horizontal members in a panel normally should be deleted asthey will overlap the horizontal members in the top of the panel below inthe final tower.

Step 3 – Draw New Members and Input Attributes• Select the Structure > Drawing Settings >Middle/End command.• Select the Structure > Draw Members command and draw in the

members required.• Select the Structure > Attributes > Section Number command

and assign section numbers to all the members.• Select the Structure > Reference Node/Axis command and

confirm the orientation of any members not matching the defaults.• Select the Structure > Material Number command and enter the

material number corresponding to the member type shown in thetable above.


MATERIAL NUMBER COMMAND

Step 4 – Make UDPSelect the Graphics to UDP File command.

GRAPHICS TO UDP FILE COMMAND

If the message box below appears you have not entered valid materialnumbers to set the member types in the UDP. Return to Step 3 andcomplete the assignment of material numbers.

MATERIAL NUMBER ERROR


Step 5 – Complete UDP DetailsComplete the entries for the UDP name and UDP type in the dialog boxshown below.

UDP DETAILS

Step 6 – Edit TD FileSelect the Tower > Build Tower > Edit Tower Data File commandand enter the lines marked below as $ NEW and $ CHANGE.

EDITING THE TD FILE

Step 7 – Process TD FileAfter modifying the Job.TD file and saving the modifications, select theTower > Process Tower Data File command and then check thestructure visually.


Modifying An Existing UDP

UDP TO GRAPHICS COMMAND

Select the UDP to Graphics command and the dialog box below will beshown. Select the UDP to be edited and proceed as if part way throughmaking a UDP.

SELECTING UDP FOR GRAPHICAL EDITING

Towers With Unequal Length LegsAt times, to save earthworks, towers built on sloping sites will have theirleg supports at different levels. This can be modelled in MStower byusing a UDP for the lowest panel. However, as the algorithm used in theloading module requires the legs to have the same foundation level, theshorter legs of the UDP must be extended with “dummy” leg membersto give the same foundation level as the longest leg.Supports will be required at the true foundation level and also at the baseof the dummy extensions. These may be specified within the SUPPORTSblock as described previously.

MSTower V5 8:Graphics Input for UDPs • 101

8:Graphics Input for UDPs

GeneralGraphics Input is the most efficient input method of inputting a user-defined panel. It involves “drawing” a structure on the screen using themouse or keyboard, and it includes many simple graphical operations,such as copying, moving, rotating, sub-dividing, and erasing. Morepowerful graphical operations include intersection, extrusion, andtransforming coordinates. In effect, MStower’s graphical input capabilityis an intelligent CAD system customized for the task of enteringstructure data.

GRAPHICS INPUT

You may find that the few hours required to become proficient atgraphical input will be well rewarded by much increased productivity increating and editing UDPs.

102 • 8:Graphics Input for UDPs MSTower V5

Note: Many MStower commands involve the use of the context menu.This is a menu, which is specific to the current operation, that appearswhen you right-click (press the right mouse button). For example, whenyou are drawing a series of members, after clicking on the DrawMembers button (the one with the pencil), you click the location of eachnode, and to finish the operation, you right-click and select Break Lineor End Line on the context menu. Also, after you have selected nodes ormembers for any operation, you right-click and choose OK or Cancel onthe context menu.

Basic DrawingGraphics Input is started by selecting Tower > Build Tower > User-Defined Panels > Graphics Edit. You will also be in Graphics Inputmode when you import an existing UDP by selecting Tower > BuildTower > User-Defined Panels > UDP To Graphics.

To start drawing a UDP, click on the toolbar button. This is the sameas selecting the Structure > Draw Members command from the mainmenu. Notice the tooltip “Draw Members” that appears when the mousecursor crosses this button. As you initiate the Draw command several things happen:1. The toolbar button displays in the depressed state, indicating that

MStower is in DRAW mode.2. “DRAW” is displayed in the status bar at the bottom of the

MStower window. 3. The prompt area of the status bar (on the left) displays the

instruction “Click on first point or enter coordinates”.4. The cursor becomes a cross.You may now click anywhere in the main window or enter coordinatesfrom the keyboard to locate the “A” node of the first member. Noticethat once the first point is specified the prompt changes to “Click on endpoint or enter coordinates; press SPACE BAR to break line”. Selectanother point and you will have drawn the first member. This point is the“B” node of the first member and the “A” node of the next member. Youmay continue selecting points to define new members.

Keyboard Entry of CoordinatesThere are many situations where the most convenient way to enter a newnode is to type the coordinates. As soon as you start to type, a dialog boxappears to accept your input.


DIALOG BOX FOR ENTERING COORDINATES

Coordinate SystemsYou may input coordinates in rectangular, cylindrical, or sphericalcoordinate systems, using standard syntax or AutoCAD syntax. Theformat of the coordinate string is described below for each syntax.STANDARD SYNTAX• Rectangular coordinates

“X Y Z”, where “X”, “Y”, and “Z” are respectively, the X, Y, and Zcoordinates of the point.

• Cylindrical coordinates“C radius theta h”, where “radius”, “theta”, and “h” are respectively,the radius, horizontal angle, and height of the point.

• Spherical coordinates“S radius theta phi”, where “radius”, “theta”, and “phi” arerespectively, the radius, horizontal angle, and vertical angle of thepoint.

Trailing zero coordinates do not have to be entered. For example, thepoint (3,0,0) may be entered as “3”. Coordinates must be separated by aspace or a comma. Coordinates relative to the last point are preceded by“R” or “r”. No separator is required after the “R” or “r”.AUTOCAD SYNTAX• Rectangular coordinates

“X Y Z”, where “X”, “Y”, and “Z” are respectively, the X, Y, and Zcoordinates of the point.

• Cylindrical coordinates“radius < theta h”, where “radius”, “theta”, and “h” are respectively,the radius, horizontal angle, and height of the point. The last twovalues must be separated by a space or a comma.

• Spherical coordinates“radius < theta < phi”, where “radius”, “theta”, and “phi” arerespectively, the radius, horizontal angle, and vertical angle of thepoint.

Coordinates relative to the last point are preceded by “@”. No separatoris required after the “@”.Breaking the LinePress the space bar or right-click and choose Break Line on the contextmenu. Notice that the cursor, the status bar, and the button show thatMStower is still in Draw mode. You may now click a new node that isnot connected to the last by a member.


Ending the LineRight-click and choose End Line on the context menu. Notice the cursorchange to the standard arrow. This indicates that the command isfinished. The status bar and the button also show that MStower is nolonger in Draw mode.

The Drawing Snap Mode

Key concept.

Initially, the status bar displays NONE for the snap mode. This meansthat the coordinates of any node defined by clicking the mouse will beindeterminate to some extent, because the degree of accuracy with whichyou can position the mouse is limited. Practically, therefore, the snapmode NONE is rarely used. The first few nodes are usually specified bygrid points or entry of coordinates. Thereafter, the Mid/End snap mode isusually used.Grid Snap Mode (GRID)In Grid mode the status bar displays GRID. Grid spacing is initially 1unit in each global axis direction but you may change it with theStructure > Drawing Settings > Grid Spacing command. When thegrid is displayed the cursor snaps to the nearest grid point. Thus, withthe mouse, you can only draw members from one grid point to another.Enter coordinates to specify a point that is not on the grid.Mid/End Snap Mode (MEND)When drawing in this mode the cursor snaps to a nearby member end ormid-point. Most graphical input is done in this snap mode. When startinga new structure you cannot enter Mid/End snap mode because there areno members to snap to.Intersection Snap Mode (INTR)When drawing in this mode the cursor snaps to a nearby intersection oftwo or more members. A new node is automatically introduced at theintersection point if there is not already a node there. When starting anew structure you cannot enter Intersection snap mode until there are atleast two members.Perpendicular Snap Mode (PERP)In this mode the cursor snaps to the point on a target member that makesthe new member perpendicular to the target member. When starting anew structure you cannot enter Perpendicular snap mode until there is atleast one member.Orthogonal Snap Mode (ORTH)In this mode you can only draw members in a global axis direction.Nearest Snap Mode (NEAR)In this snap mode the cursor snaps to the point on a target member that isnearest to the cursor location.


Changing the Snap Mode “On the Fly”A very convenient feature is the ability to change the snap mode during adraw operation. For example, you may click the start point of a newmember at the end of another while in Mid/End snap mode and thenchange to Grid snap mode to select the end point. Right-click to displaythe context menu with its selection of snap modes (see diagram at thebeginning of this chapter).

The Drawing PlaneThe drawing plane is a plane on which nodes are located when you drawin either the Grid or NONE snap modes. For example, when drawing inGrid snap mode with default settings, the drawing plane is X-Y at anoffset of zero along the Z axis. This means that all new nodes drawn inGrid or null snap mode have a Z coordinate of zero. Changing the viewwith any of the Front View, Back View, Right View, Left View, orTop View commands automatically changes the drawing plane so that itis parallel to the view plane.Use the Structure > Drawing Settings > Drawing Plane command tochange the drawing plane as required. If you change the view or thedrawing plane so that it (the drawing plane) is at right angles to the viewplane (the plane of the screen) you may see the warning message shownbelow and you may not be able to click a new point.

WARNING THAT DRAWING PLANEIS PERPENDICULAR TO SCREEN

Automatic Removal of Duplicate Nodes and MembersAt various stages during graphical input operations, MStower removesany duplicate nodes or members that are detected. The first node ormember to be drawn will remain and any that are superimposed will beremoved automatically. This behaviour has two significantconsequences:• Overlapping nodes and members in copy operations are ignored.• In drawing members, you may draw over an existing member

instead of breaking the line.


Cursors

Key concept.

MStower displays various cursors at different times, depending uponwhat is happening. These cursors are shown below:

Cursor DescriptionCommand mode. MStower is waiting for you to select a commandfrom the menu, click a toolbar button, or select a node or member (thecursor changes as soon as you select a node or member).Drawing mode. MStower is waiting for you to click an end of amember. Look at the right of the status line to determine which snapmode is in effect. You may use the Structure > Drawing Settingscommand or the context menu to change the snap mode withoutleaving the current drawing command.Member selection mode. MStower is waiting for you to select one ormore members by clicking on them or enclosing them in a selectionbox. If you drag a selection box from left to right, cut members areexcluded. Dragging from right to left includes cut members.

Node selection mode. MStower is waiting for you to select one ormore nodes by clicking on them or enclosing them in a selection box.

This cursor appears when you are selecting a zoom window orpanning. When zooming, drag from one corner to the diagonallyopposite corner of the rectangle you want to zoom to. When panning,click on any part of the structure and drag to the new location for thatpart.

Generally, when you have finished a command, MStower allows you torepeat the command until you cancel the command by right-clicking. Forexample, when you select the Structure > Erase Members command,the cursor changes, you then select members you want to erase andconfirm the selection by right-clicking and choosing OK on the contextmenu. The member selection cursor is still displayed, allowing you tochoose more members to erase. To terminate the command, right-click,and the standard arrow cursor will reappear.Many commands are interruptible. This permits you to adjust the viewduring a command. When drawing members in a large model, forexample, having clicked the “A” node of a member, you may need tozoom in to another region of the structure before clicking the “B” node.


Shortcut KeysMStower permits the use of shortcut keys to some commands. Shortcutkeys are also known as accelerator keys. Below is a complete list ofMStower’s shortcut keys:

Shortcut CommandCtrl+C CopyCtrl+X CutCtrl+V PasteCtrl+Z UndoCtrl+Y RedoF5 RedrawCtrl+A Select AllDelete Erase MembersHome Zoom Extents/Limits

Viewpoint LeftViewpoint RightViewpoint UpViewpoint Down

Space Break Line

The effect of pressing a shortcut key depends on the context. Forexample, pressing Delete usually deletes selected members, but in adialog box it may delete text.

Selecting Nodes and Members

Key concept.

In MStower, when you choose a command, you usually select the nodesor members that are the object of the command. This may be done inseveral ways:• Clicking each node or member in turn. Clicking again on a node or

member deselects it.• Dragging a selection box that encloses the nodes or members to be

selected. “Dragging a selection box” means clicking (with the leftmouse button) a point away from the nodes or members to beselected, then dragging the mouse until the selection box enclosesthe necessary nodes or members, and finally, releasing the leftmouse button. Note that when the selection box is dragged fromright to left, a “crossing window” appears, which selects not onlymembers enclosed by the box but also members cut by the sides ofthe box.


• Clicking a selection box. This is similar to dragging a selection boxbut instead of clicking, dragging, and releasing the mouse button,you click two points to define diagonally opposite corners of theselection box.

• All members may be selected by Ctrl+A (see “Shortcut Keys“,above).

In all cases, you confirm the selection by right-clicking and choosingOK on the context menu.

Right-Clicking on Nodes and Members

Key concept.

MStower fully implements the Windows protocol for right-clicking onobjects to obtain a pop-up of related commands. This provides analternative method of operation:• Select node(s) or member(s).• Right-click to choose required operation on context menu.Right-clicking on a node will cause this context menu to appear:

NODE CONTEXT MENU

Double-clicking on a node is the same as selecting Properties on thispop-up menu.The following pop-up menu appears when you right-click on a member:

MEMBER CONTEXT MENU

Double-clicking on a member is the same as selecting Properties on thismenu.


The Node Properties Dialog BoxThe dialog box shown below appears when you double-click a node orselect Properties after right-clicking a node.

NODE PROPERTIES DIALOG BOX

The OK button in this dialog box is disabled. You may use the dialogbox to check properties but you will not be able to change them.

The Member Properties Dialog BoxThe dialog box shown below appears when you double-click a memberor select Properties after right-clicking a member.

MEMBER PROPERTIES DIALOG BOX

The OK button in this dialog box is disabled. You may use the dialogbox to check properties but you will not be able to change them.


Properties Dialog Boxes with Multiple Selection

Key concept.

You may select several nodes or members, then right-click and chooseProperties on the context menu. The dialog box will display commonproperties of the selected group of nodes or members. Blank edit boxesindicate that the corresponding value is not the same for all of themultiple selection.

Extrusion

Key concept.

There is a check box for “Extrude nodes” in each of the Linear Copy,Polar Copy, and Reflect dialog boxes. When you perform a copyoperation you may “extrude” each copied node into a series of members– in other words, there will be a string of new members lying on the pathtraced out by each node involved in the copy operation. The member xaxis is aligned with the direction of extrusion.

Interrupting CommandsThe diagram below shows the View toolbar, normally docked at the topof the MStower window.

VIEW TOOLBAR

Most commands may be interrupted in order to change the view byclicking on one of these buttons. This is helpful in many situations, forexample, when drawing a member, and the view required for displayingthe “B” node is different from that in which the “A” node is visible. Youmay interrupt graphical commands to rotate the view, zoom in to acongested area of the model, or pan the view, as required.You may also interrupt commands by clicking buttons on the Displaytoolbar, shown below.

DRAW TOOLBAR


The Stretch CommandThe Structure > Move > Stretch command applies a lineartransformation to the coordinates of selected nodes. The prompts in thestatus bar guide you through the necessary steps in this command:• Select nodes• Select node as fixed point• Select node as start point of stretch vector• Select node as end point of stretch vectorAn example is illustrated below, where the top chord nodes of a truss are“stretched” to introduce a uniform slope from one end to the other.

Firstly, a member is added to represent the stretch vector. All the nodesto be transformed are highlighted. Node 2 is selected as the fixed node.

Nodes 12 and 13 are selected to define the stretch vector. The diagrambelow shows the truss on completion of the command.

If you inadvertently click on the wrong node when selecting the fixednode or the start of the stretch vector, you can abort the command byselecting the start of the stretch vector as the end point also.The Stretch command could be used to input tower cross-arms as aparallel chord truss, which is later tapered, as in the example above.


The Limit Command

VIEW > LIMIT > WINDOW

The commands on the View > Limit menu allow you to restrict activityto a selected part of the structure. The rest of the structure may be greyedout or hidden from view. This has the advantage that the view you areworking on is uncluttered by irrelevant detail and the rest of the structureis inaccessible while Limit is in effect.

The Limit > Window command, , was used to select one segment ofthe tower in the diagram below. To hide the rest of the structure right-click and uncheck Show Outside Limits.

LIMIT > WINDOW


When the Limit command is in effect, clicking this button, ,(equivalent to the View > Zoom > Extents/Limits command) will zoomthe view so that the full structure and the limited part alternately fill thescreen.

The Limit > Boundary command, , may be used to select a part ofthe tower using a selection polygon.

Clicking the Full View button, , reverses the effect of the Limitcommand.

Removing an Intermediate NodeYou may occasionally want to remove an intermediate node in amember. If you had accidentally sub-divided a member (while drawingin Mid/End snap mode, for example), you may want to restore it to asingle member. This can easily be done as follows:1. Select Mid/End snap mode if this mode is not already selected.2. Right-click on the intermediate node to be removed.3. Select Move Node on the context menu – the node should now be

attached so you can drag it.4. Drag the node to one end of the member containing it and click.This procedure does not give rise to a duplicate node or a zero-lengthmember.


MSTower V5 9:Tower Loading • 115

9:Tower Loading

GeneralThis chapter describes the operation of the MStower loading module incomputing loads on the tower and ancillaries in accordance with therequirements of:• BS 8100:Part 1 1986.• BS 8100:Part 4 1995.• CP3 Chapter 5.• AS 3995-1994.• Malaysian Electricity Supply Regulations 1990.• EIA/TIA-222-F-1991.Loading types include dead load, ice load (with and without wind), nodeloads, wind loading on the structure, its ancillaries, feeders, andattachments, and temperature loads.Tower loading represented as node loads are computed for wind actingat any angle to the tower, with and without icing of members, as well asgravity loads due to self weight and icing. Additional node forces maybe specified for any primary load case. Combination load cases may alsobe defined.Code partial safety factors may be specified directly or as factors incombination load cases.Tower FacesThe faces of the tower are numbered 1, 2, 3 (and 4 for rectangulartowers) in an anti-clockwise direction with face 1 normal to the positiveX axis. The locations of face ancillaries are specified by reference to theface numbers.Towers With Cross-ArmsAlthough the structure may have cross-arms, their presence is ignoredwhen allocating members to faces and in the subsequent computation ofwind loads. Additional face ancillaries should be added to theappropriate panels to account for the wind resistance of the cross-arms.The weight of the cross-arms and any encrusting ice is taken intoaccount in DL and ICE load cases respectively.

116 • 9:Tower Loading MSTower V5

The Tower Loading (TWR) FileData describing the tower loading is entered into a free-format text filecalled Job.TWR, where “Job” is the job name. A tower loading file maybe generated by selecting Tower > Load Tower > Make TowerLoading File. A series of dialog boxes will be displayed for you toselect the loading code and various parameters. The resulting TWR filewill require some editing to customize it to the particular tower you aremodelling.The data is organized into logical blocks:1. Parameters block.2. Terrain block.3. Velocity profile block (optional).4. Named node block (optional).5. Guy list block (optional).6. Loads block.7. Panel block (optional).8. Ancillaries block.Each block commences with a keyword identifying the block andterminates with the keyword END. The keyword EOF is used toterminate the file. Each data block is described in this chapter.

Parameters BlockPARAMETERS

ANGN an[CODE code][ICE RO ro RW rw][ALTOP alt][PSF-V gamma-v][PSF-M gamma-m]VB vb vtype[OVERLAP n][GRAV grav][RHO rho]

END

where:ANGN Keyword.an The angle, in degrees, measured anti-clockwise from the X axis

to geographic north.CODE Keyword.code Character string indicating the code rules to be followed in

computing the wind and other loading:BS8100 Use the rules of BS 8100:Part 1 1986.


BS8100P4 Use the rules of BS 8100:Part 4 1995.MER Use the rules of the Malaysian Electricity Supply Regulations 1990 – See note below.AS3995 Use the rules of AS 3995-1994.EIA222 Use the rules of EIA/TIA-222-F-1991.If omitted, the rules of BS 8100 Part 1 will be used. Unlessspecified otherwise all code references are to BS 8100.

ICE Keyword.RO Keyword.ro Radial ice thickness, mm or inches, in the absence of wind (Fig.

3.9 in BS 8100).RW Keyword.rw Radial ice thickness, mm or inches, in presence of wind (Fig.

3.9 in BS 8100).ALTOP Keyword.alt Altitude of tower top, in m or ft. Used to determine basic ice

thickness (Cl. 3.5.2 in BS 8100).PSF-V Keyword.gamma-v Partial safety factor on wind speed and ice thickness (Fig 2.1 in

BS 8100). For BS 8100 only.PSF-M Keyword.gamma-m Partial safety factor on design strength (Fig. 2.1 in BS 8100).

For BS 8100 only.VB Keyword.vb Basic wind velocity in m/sec or miles/hour (Fig. 3.1 in

BS 8100).vtype Character string whose value depends on loading code as

shown below:BS 8100 MEAN = Mean hourly wind speed.

AS 3995 GUST = Gust wind speed.

EIA222 Blank = Fastest mile wind speed.CP3 GUST = Three second gust wind speed.

MER GUST = No additional gust factor applied by program.Refer to individual codes for a full definition of the wind speedto be used.


OVERLAP Keyword.n Overlap flag; 0 if overlap between bracing and leg members is

not to be taken into account; 1 otherwise. If overlap is takeninto account, the computed wind resistance will be smaller, butcomputation time will be marginally longer. Overlap will betaken into account if flag is omitted.

GRAV Keyword.grav Gravitational acceleration in Z direction. If omitted, an

acceleration of -9.81 m/sec² or –32.2 ft/sec² will be used incomputing gravitational loads from masses.

RHO Keyword.rho Density of air at the reference temperature. If omitted, a value

of 1.22 kg/m3 or 0.075 lb/ft3 will be used.

Note: If code is specified as MER the following default values will beused unless otherwise specified:gamma-v = 1.0gamma-m = 1.0rho = 1.2 kg/m3

vb = 26.82 m/s

Terrain BlockThis block is used to specify the variation of terrain factor with winddirection around the tower. The data required depends on the loadingcode being used.The TERRAIN block for BS 8100 Part 1 is as follows:TERRAIN

ANGLE angle TCAT tcat [Kd kd] [KR kr] [HH hh]...[BETAH betah] [XLEE xlee]

...END

where:ANGLE Keyword.angle Wind angle in degrees (clockwise) from geographic north.TCAT Keyword.tcat Terrain category in Arabic numerals. Intermediate terrain

categories may be given as a decimal, e.g. 2.5.KR Keyword.kr Terrain roughness factor. Interpolated from BS 8100 Table 3.1

if not specified.KD Keyword.kd Wind direction factor. Interpolated from BS 8100 Fig. 3.2 if not


specified. If ice is present a maximum value of 0.85 will beused.

HH Keyword.hh Height of hill above general terrain, in m or ft. Assumed to be

zero if not specified.BETAH Keyword.betah Effective slope of hill , in degrees. Assumed to be zero if not

specified.XLEE Keyword.xlee Downwind distance from the crest of the hill to tower site, in m

or ft. Assumed to be zero if not specified.

The TERRAIN block for BS 8100:Part 4 is as follows:TERRAIN

ANGLE angle [SD sd] DSEA ds DTWN dt...[XO xo HO ho HE he LU lu X x]

...END

where:ANGLE Keyword.angle Wind angle in degrees east of north.SD Keyword.sd Direction factor (BS 8100:Part 4 Cl. 3.1.5). If not specified a

value will be interpolated from Table 1 of BS 8100:Part 4. Ifice is present a maximum value of 0.85 will be used.

DSEA Keyword.ds Distance from the sea, in km or miles.DTWN Keyword.dt Distance to edge of town in windward direction, in km or

miles. Zero for country terrain.XO Keyword.xo Upwind spacing of permanent obstructions from mast, in m or

ft.HO Keyword.ho General level of rooftops, in m or ft.HE Keyword.he Effective height of topographic feature above general ground

level in upwind direction, in m or ft.LU Keyword.lu Length of upwind slope in wind direction, in m or ft.X Keyword.


x Horizontal distance of site from top of crest, in m or ft.

The TERRAIN block for AS 3995-1994 is as follows:TERRAIN

ANGLE angle TCAT tcat [MD md H h LU lu X x] reg...

END

where:ANGLE Keyword.angle Angle in degrees (clockwise) from geographic north.TCAT Keyword.tcat Terrain category in Arabic numerals. Intermediate terrain

categories may be given as a decimal, e.g. 2.5.MD Keyword.md Wind direction multiplier. If not specified, a value will be

interpolated from Table 2.2.5 of AS 3995.H Keyword.h Height of feature, in m or ft.LU Keyword.lu Horizontal distance upwind from the crest of the feature to a

level half the height below the crest, in m or ft.X Keyword.x Horizontal distance upwind or downwind from the structure to

the crest of the feature, in m or ft.reg Regional code – A1, A2, A3, A4, B, C, or D, as defined in Fig.

2.2 of AS 3995.

The topographic multiplier, Mt (AS 3995 Cl. 2.2.4), is computed in eachdirection from the values of h, lu, and x entered in the TERRAIN block.

No TERRAIN block is required for the Malaysian Electricity SupplyRegulations.Terrain factors for up to eight directions may be entered. If necessary,intermediate values will be obtained by interpolation. If there is novariation in terrain with angle, enter a single set of values for angle zero.The TERRAIN block may be omitted, in which case a terrain category of1 will be assumed (tcat = 1). The TERRAIN block will be ignored if auser-defined velocity profile is specified.


Velocity Profile BlockThis optional block may be used to specify a velocity profile that takesprecedence over any profile that may be computed from the code terrainrules.VELOCITY

ZF z VF vfact...

END

where:ZF Keyword.z Height above ground level at which velocity factor is specified,

in m or ft.VF Keyword.vfact Velocity factor at height z. The actual velocity is:

Vz = Vb × gamma-v × vfact

The velocity profile should be entered in increasing order of height.Additional wind profiles may be defined for determining patch loads onmasts:PVEL_MAST

ZF z VF vfact...

END

PVEL_GUYZF z VF vfact...

END

If PVEL_MAST and PVEL_GUY blocks are defined a number of “patch”load cases will be generated as described in this chapter.


VELOCITY PROFILE

Named Node BlockUp to 40 nodes may be “named” by being assigned an alphanumeric tag:NODENAME [ZREF zref]

name X x Y y Z z...

END

where:ZREF Keyword.zref Location of the origin from which the Z coordinates of the

named nodes are measured. Valid values are:zr Z coordinate in m or ft.TOP Keyword indicating that the Z coordinates of the nodes are measured from the topmost node of the tower. Nodes will have negative Z coordinates.BTM Keyword indicating that the Z coordinates of the nodes are measured from the lowest node in the tower.

name An alphanumeric string of characters. It is limited to 8characters and must not be recognizable as a number.

X Keyword.x X coordinate of the node, in m or ft.Y Keyword.y Y coordinate of the node, in m or ft.


Z Keyword.z Z coordinate of the node, relative to the origin defined by

ZREF, in m or ft. If ZREF has not been defined the Zcoordinate will be relative to the global origin.

The node list establishes node number aliases that may replace a nodenumber anywhere in the TWR file. The aliases may be useful wheremodifications to the geometry results in node numbers changing, forexample, when the tower is being studied for strengthening or a numberof different bracing patterns are being considered. If a family oftransmission towers is being designed the node list could define theloading points with only the ZREF parameter being changed asextensions are added.

Guy List BlockThis optional block allows you to group a number of guys together andto refer to them by name when considering asymmetrical ice loading inice and wind load cases. Up to eight lists of guys may be input:GUYLIST

name g1 ... gn...

END

where:name An alphanumeric string of characters. It is limited to 8

characters and must not be recognizable as a number.g1..gn List of member numbers for the guys in this list.

A particular guy may belong to more than one list.

Note: You may obtain the member number for a guy from the data tipthat appears when the cursor is placed on it, with the Query > MemberData command, or by double-clicking on it.

Loads BlockThis block describes the load cases that are to be computed. Eachprimary load case consists of a CASE description, a specification for awind, dead, or ice load, and optionally, additional node loads that are toform part of that load case. Combination load cases consist of a CASEdescription and a number of load case references and factors.All loads on the tower should be described in the LOADS block.LOADS


CASE ...Wind, dead, ice, or miscellaneous loadAdditional node loadsAdditional member temperatures

CASE ...Wind, dead, ice, or miscellaneous loadAdditional node loadsAdditional member temperatures

...

CASE ...Combination load case...

END

Each load case must start with the line:CASE lcase title

where:lcase 1-5 digit load case reference number.title Load case title – up to 50 characters.

Wind Load CasesWL {ANGLE wangn | ANGLX wangx} [{ICE|NOICE}]...

[BARE] [CROSS] [{PATCH|NOPATCH}] [SMEAR][UNICE list]

where:ANGLE Keyword.wangn Angle in degrees (clockwise) from geographic north.ANGLX Keyword.wangx Angle in degrees (anti-clockwise) from the global X axis.ICE Keyword indicating that ice is to be considered for this case.NOICE Keyword indicating that ice is not to be considered for this

case.BARE Keyword indicating that wind load is to be computed for the

bare tower, i.e., the tower without any ancillaries.CROSS Keyword indicating that MStower is to generate sub-load cases

in the cross-wind direction.PATCH Keyword indicating that patch load cases will be generated for

guyed masts.NOPATCH Keyword indicating that patch load cases will not be generated

for guyed masts.


SMEAR Keyword indicating that patch wind load on guys will be“smeared” over the length of the guys according to the rules ofENV1993-3-1:1997, Para A.4.3.2.3.

UNICE Keyword.list Name of a guy list defined in the GUYLIST block. The guys

nominated in this list will have wind loads applied to the bareguy, not to the iced diameter of the guy.

If the MEAN wind speed is being used the basic wind load case lcasecontains the loads due to the mean hourly wind applied to the equivalentbare tower. This is followed by sequentially numbered sub-cases, thefirst containing the fluctuating component of the wind load on the largeancillaries, and the second the sum of the mean hourly loads on thetower and ancillaries.The CROSS wind load cases are required additional sub-cases containingthe loads due to cross-wind on the equivalent bare tower and thefluctuating component of the cross-wind on the ancillaries are generated.If the GUST wind speed is being used, the along-wind loads on the largeancillaries are accumulated into the basic wind load case and noadditional sub-loads are formed. You must leave gaps in the numberingof wind load cases to accommodate the sub-cases; a difference of tenbetween successive cases is sufficient and convenient.

Guyed Mast Patch LoadingsFor a guyed mast, the program can generate a set of patch load sub-casesas defined in BS 8100:Part 4 Cl. 5.3.2.2. These are:1. On each span of the mast column between adjacent guy levels (and

on the span between the mast base and the first guy level).2. Over the cantilever, if relevant.3. From midpoint to midpoint of adjacent spans.4. From the base of the mid-height of the first guy level.5. From the mid-height of the span between the penultimate and top

guy to the top guy if no cantilever is present, but including thecantilever, if relevant.

For BS 8100, the patch loads are derived from equivalent velocityprofiles derived from the equations in Cl. 5.3.2.2 and Cl. 5.3.2.3 for themast and guy, respectively.For AS 3995, the mean hourly wind profile is used with segments ofgust wind profile forming the load patches. If patch loads are notrequired, the wind profile specified in the PARAMETERS block will beused.If specified, the various wind profiles needed to form patch load caseswill be obtained as follows:


VELOCITY Mean wind profile.PVEL_MAST Patch wind profile on mast.PVEL_GUY Patch wind profile on guys.

Formation of patch sub-cases may be prevented by using the keyword.NOPATCH when specifying the wind load.If patch loading is specified, you must leave a sufficient gap in thenumbering of successive wind load and combination load cases toaccommodate the sub-cases that will be generated. The total structuralresponse for the mean wind and patch cases is computed in accordancewith BS 8100:Part 4 Cl. 5.3.2.4.

Dead LoadsDL [BARE]

where:DL Keyword signifying a dead load case. The weight of all

ancillaries will be included in the load case.BARE Keyword. If present, the dead load is computed for the tower

structure only, without ancillaries.

Ice LoadsICE DENS dens {WIND|NOWIND} [BARE] [UNICE list]

where:ICE Keyword signifying a gravity load due to icing of the tower.

The weight of ice coating structural members and ancillarieswill be taken into account.

DENS Keyword.dens Specific weight of ice, in kN/m3 or lb/ft3.WIND Keyword indicating presence of wind.NOWIND Keyword indicating absence of wind.BARE Keyword indicating that ice load is computed for the tower

structure only without ancillaries..UNICE Keyword.list Name of a guy list defined in the GUYLIST block. The guys

nominated in this list will not have ice applied.


Miscellaneous LoadsLoad cases not falling into one of the above categories may be includedas miscellaneous loads. These could include construction, maintenance,or similar loads.MI

NDLD list FX fx FY fy FZ fz...

where:MI Keyword.NDLD.. See “Additional Node Loads”, below.

Additional Node LoadsAdditional node loads may specified for any wind load, dead load, or iceload case.NDLD list FX fx FY fy FZ fz

where:NDLD Keyword.list The nodes to which the forces are to be applied, in one of the

following forms:n1 n2 ... nn

A list of node numbers.n1 TO n2 INC n3

Includes n1 to n2 in steps of n3.ALL

All nodes.FX FY FZ Keywords indicating direction of force.fx fy fz Forces in the global X, Y, Z directions, respectively, in kN or

kips.

Additional Member TemperaturesAdditional member temperatures may be specified for any wind load,dead load, or ice load case.MTMP list TEMP t

where:MTMP Keyword.list The members to which the temperatures are to be applied, in

one of the following forms:m1 m2 ... mn

A list of node numbers.m1 TO m2 INC m3


Includes m1 to m2 in steps of m3.ALL

All members.TEMP Keyword.t Centroidal temperature. Transverse temperature gradients will

be set to zero.

In addition to being used to model the effects of temperature change,MTMP loads may be used to simulate a broken guy, by specifying atemperature increase sufficient to make the guy slack.

Combination Load CasesCOMBIN lcase factor...

where:COMBIN Keyword.lcase Load case reference number. This must be a load case reference

numbers specified in a CASE record – do not refer to sub-casesgenerated for groups of large ancillaries or cross-winds or patchload cases.

factor Factor by which the loads in lcase are to be multiplied.

Panel BlockThe panels into which the tower is divided are defined by listing nodes atthe panel boundaries in order from the top of the tower. The Zcoordinates of these nodes will be used when determining the panel towhich projected areas of member and ancillaries are allocated. The list ofnodes may extend over one or more lines. If the PANEL block is notspecified panel heights will be obtained from the Job.TWM file,generated by the tower builder. The PANEL block is not usuallyrequired.

Ancillary BlockThis block is used to describe the ancillaries attached to the tower. Datafor each ancillary is given on a separate line as a series of keywords andnumeric items. Ancillary libraries, containing the dimensions and otherproperties of ancillaries, are used to reduce the amount of data required.Ancillaries are sub-divided into the following types:• Linear ancillaries.• Face ancillaries.• Large ancillaries.• Insulators


ANCILLARIES


ANCILLARY AXES

Linear AncillariesLinear ancillaries are items such as wave-guides, feeders and the like.Usually they are either attached to the face of the tower or containedwithin the body of the tower. The following data is required:LINEAR LIB libr

name XB xb YB yb ZB zb [XT xt] [YT yt] ZT zt ...[SELF] LIB lname [FACT fact] [SHADE shade] ...[SHADY shady] ANG anga

...

where:LINEAR Keyword.LIB Keyword.


libr Name of library containing linear ancillaries. It is assumed thatthe library is located in the data folder unless the name isprefixed with “P:” or “L:”. “P:” indicates that the library is inthe program folder and “L:” indicates that it is in the libraryfolder.

name Identifier for the ancillary, 1-16 characters, not recognizable asa number.

XB Keyword.xb X coordinate of the base of the ancillary, in m or ft.YB Keyword.yb Y coordinate of the base of the ancillary, in m or ft.ZB Keyword.zb Z coordinate of the base of the ancillary relative to the base of

the tower, in m or ft.XT Keyword.xt X coordinate of the top of the ancillary, in m or ft. If not

entered, the X coordinate of the base of the ancillary is used.YT Keyword.yt Y coordinate of the top of the ancillary, in m or ft. If not

entered, the Y coordinate of the base of the ancillary is used.ZT Keyword.zt Z coordinate of the top of the ancillary relative to the base of

the tower, in m or ft. This value must be entered.SELF Keyword indicating that the linear ancillary is self-supporting.

The mass of the ancillary will be allocated to panels whencomputing the equivalent static factor but its self weight willnot be added to the tower when computing DL cases. Ifomitted, the weight of the ancillary will be added to that of thetower.

LIB Keyword.lname Name of ancillary in library – 1-16 characters.FACT Keyword.fact Number of ancillaries of this type at this location.SHADE Keyword.shade Coefficient used to factor exposed area of a linear ancillary.SHADY Keyword.shady Coefficient used to factor exposed area of linear ancillaries for

wind the “y” direction.ANG Keyword.ang Angle between the “x” axis of the ancillary and the X axis of

the tower measured clockwise from the X axis.


Face AncillariesThese are ancillaries mounted on the faces of the tower and consisting ofsmall items whose wind resistances will be added to that of the panel ofthe face to which they are attached.FACE

name FACE flist ZA za MASS mass CN cn ...AREA area AICE aice {FLAT|CYL}

...

where:FACE Keyword.name Identifier for the ancillary – 1-16 characters, not recognizable

as a number.FLIST Keyword.flist List of faces to which ancillaries of this type are attached, as a

concatenated string of the digits 1, 2, 3, and 4, with noembedded spaces, e.g. 13 means the ancillaries are on faces 1and 3.

ZA Keyword.za Z coordinate of the mounted level of the ancillary, in m or ft.MASS Keyword.mass Mass of the ancillary, in kg or lb.CN Keyword.cn Drag coefficient for wind normal to the face to which the

ancillary is attached.AREA Keyword.area Projected area of the ancillary on the face of the tower, in m2 or

ft2.AICE Keyword.aice Surface area that can be coated with ice, in m2 or ft2. The

volume of ice is obtained by multiplying this area by thethickness of ice.

FLAT Keyword indicating that the ancillary is to be considered assharp edged.

CYL Keyword indicating that the ancillary is to be considered ascylindrical.


Large AncillariesThese are discrete ancillaries too large to be considered as “face-mounted” ancillaries, usually positioned on the face of the tower orexternal to the tower.Large ancillaries are described:LARGE LIB libr

name XA xa YA ya ZA za LIB lname ...[FACT fact] [SHADE shade] ANG ang ...[{AMASS|TMASS}] [ATTACH nlist]

...

where:LARGE Keyword.LIB Keyword.libr Name of library containing large ancillaries. It is assumed that

the library is located in the data folder unless the name isprefixed with “P:” or “L:”. “P:” indicates that the library is inthe program folder and “L:” indicates that it is in the libraryfolder.

name Identifier for the ancillary – 1-16 characters, not recognizableas a number.

XA Keyword.xa X coordinate of the ancillary, in m or ft.YA Keyword.ya Y coordinate of the ancillary, in m or ft.ZA Keyword.za Z coordinate of reference level of the ancillary relative to the

base of the tower, in m or ft. If an antenna, the reference levelis usually the center of radiation.

LIB Keyword.lname Name of ancillary in library – 1-16 characters.FACT Keyword.fact Factor by which the library dimensions and areas of the

ancillary are multiplied. If not given, a value of 1.0 is used.SHADE Keyword.shade Coefficient used to factor exposed area of a large or linear

ancillary.ANG Keyword.ang Bearing of the ancillary, the clockwise angle between north and

the negative “x” axis of the ancillary.AMASS Keyword.TMASS Keyword.mass Mass, in kg or lb, with the following meanings depending on

which keyword it follows:


AMASS Additional mass, to be added to the library mass.TMASS Total mass, to be used instead of the mass in thelibrary.

ATTACH Keyword.nlist List of nodes to which the ancillary is attached. If attachment

data is omitted, the program will allocate the forces from theancillary to leg nodes closest to the level of the ancillary. Theforces of the ancillary will be transferred into the tower by astatically equivalent set of forces on the listed nodes.

An ampersand, “&”, may be used at the end of a line to indicate that thedata for an ancillary extends to the next line.If the mean wind speed is being used, the gust factor for each largeancillary will be computed and the product of the gust factor and themean hourly loads will be accumulated to form a single sub-load case foreach wind load case.

InsulatorsThese may be used to separate sections of a multi-segment guy. They aredescribed as:INSULATORS

name NODE node AREA area AICE aice ...MASS mass CN cn

...

where:INSULATORS Keyword.name Identifier for the insulator – 1-16 characters, not

recognizable as a number.NODE Keyword.node Node number at which the insulator is located.AREA Keyword.area Projected area of the insulator, in m2 or ft2. It is assumed that

the projected area is the same for all angles of windincidence.

AICE Keyword.aice Surface area that can be coated with ice, in m2 or ft2. The

volume of ice is obtained by multiplying this area by thethickness of ice.

MASS Keyword.mass Mass of the insulator, in kg or lb.CN Keyword.cn Drag coefficient, assumed to be the same for all angles of

wind incidence.


Note: You may obtain the node number for an insulator from the datatip that appears when the cursor is placed on it, with the Query > NodeData command, or by double-clicking on it.

OutputThe following tables of intermediate results computed by the loadingmodule are written to a loading log file and may be viewed by selectingthe File > List/Edit > Loading Log command or printed by selectingthe File > Print > Loading Log command.Velocity TableThe input and computed parameters used in computing the velocityprofile and the variation of velocity with height above the base of thetower are reported.Member/Face TableEach member is allocated to a tower face and its projected length in theface is reported. Leg members will belong to two faces while internalmembers, such as hip and plan bracing, will not belong to any face. Thelength of bracing members that intersect leg members is adjusted for theoverlap between the IP and the edge of the leg member if the overlapflag in the PARAMETERS block is set to 1.Face ResultsThe area of each panel, its solidity ratio, and drag coefficient, theresistance of ancillaries, shielding factor, Sf, and the normal resistance ofthe face as a single frame are reported for each face.Resistance TableThe effective resistance, Re1 and Re2, and the total wind resistance,Rwt, for the specified wind angle are reported, along with the total mass(structural and ancillary) of each panel.The factor determining whether the equivalent static method is valid isalso reported.


MethodThe program uses the procedures set out in Section 4.4 of BS 8100 forthe computation of resistances.If the mean-hourly wind speed is being used and if large ancillaries arespecified in a wind load case, the wind loads on the equivalent shieldedtower will be computed and additional sub-load cases will be generatedfor each wind direction for the large ancillaries. This case will containthe sum of the gust-factored wind loads on the large ancillaries.If the gust wind speed is being used, the loads on the equivalent shieldedtower and large ancillaries are computed separately and added togetherto form a single load case before being output.

BS 8100The velocity, VB, should be specified as MEAN.MStower uses the general method of BS 8100 for computing the windresistance of towers. This method allows for towers with faces that areasymmetrical, either structurally or due to their complement ofancillaries. It also allows the resistance to be computed for any windincidence angle. When using the general method, the resistance of thesingle frame comprised in each face is computed, along with shieldingfactors and Kth. The resistance of the complete tower is built up fromthese values. Methods of computing drag coefficients of panels made offlat and circular sections (both sub-critical and super-critical) are alsogiven. BS 8100 also uses a simpler method for symmetrical towers,whereby the resistance for the complete tower can be determined fromdrag factors for the overall tower.If a panel contains ancillaries, the projected area of the ancillary is usedwhen computing panel solidity ratios and single panel drag coefficients.The wind forces on the ancillary are then computed using the dragcoefficients from the ancillary library and a statically equivalent set ofnode loads is applied to the nodes to which the ancillary is attached.

CP3 Chapter 5The velocity, VB, should be specified as GUST.When wind loading to CP3 Ch. 5 is to be calculated, the wind load codeentry should be left blank and the three second gust wind speed shouldbe specified. It is also necessary to define a wind velocity profile in aVELOCITY block as no equation is given for this in CP3 Ch. 5. In theabsence of a VELOCITY block the velocity profile in BS 8100 will beused.

AS 3995The velocity, VB, should be specified as GUST.


When AS 3995 is specified, MStower uses the general method asdescribed above but with single frame drag coefficients that give overalldrag coefficients equal to those in Table 2.2.8.2 of AS 3995. This allowsthe program to maintain the ability to deal with towers that areasymmetrical or composed of mixed section shapes. It also allows windforces to be computed for angles of incidence other than face and corner.For a tower carrying large dishes, the critical wind may occur at someother angle, which may vary from member to member.If loads are being computed for a mast, MStower will use code-definedmean and gust wind profiles in computing patch load cases.

Malaysian Electricity Supply Regulations 1990If the code in the PARAMETERS block is specified as MER (MalaysianElectricity Supply Regulations), the program uses the formulae andmethods of BS 8100, but with the following differences:• Wind velocity is constant over the full height of the tower. A

velocity equal to the product of the basic wind velocity and thepartial safety factor on wind speed is used.

• A solidity ratio of 0.1 is used to determine the single frame dragcoefficient (BS 8100 Fig. 4.5). When used with the wind velocityspecified in the regulations this gives a wind pressure of 810 N/m2

on the projected area of a face made up of flat sided members.The effective shielding factor in C1.4.4.1 of BS 8100 is taken as 0.5,giving an additional 405 N/m2 on the leeward face.

EIA/TIA-222-FThe wind velocity, VB, should be the fastest mile wind speed. Nomodifying keyword (MEAN or GUST) is required. Unless a user-definedprofile is used, the velocity profile will be computed in accordance withCl. 2.3.3. A TERRAIN block is not required.When EIA222 is specified, MStower uses the general method asdescribed above but with modifications to coefficients that give overalldrag coefficients equal to those derived from Section 2.3 of EIA/TIA-222-F for the wind directions specified in Table 2. This allows theprogram to maintain the ability to deal with towers that are asymmetricalor composed of mixed section shapes. It also allows wind forces to becomputed for any incidence angle instead of just face and corner wind.For a tower carrying large dishes, the critical wind may occur at someother angle, which may vary from member to member.All wind loads, including any NDLD forces specified in a WL case, aremultiplied by a gust response factor determined in accordance with Cl.2.3.4.MStower is unable to compute patch loading for EIA-222 unless specificvelocity profile tables are entered.


BS 8100 Gust Factor CorrectionIf BS 8100:Part 1 is specified with a mean hourly wind speed, each windload case will consist of:1. A load case containing forces on the equivalent bare tower due to

the mean wind.2. A sub-load case containing forces on the large ancillaries due to the

mean wind multiplied by the gust factor appropriate to eachancillary’s size and height above ground level.

3. A sub-load case containing the sum of the mean wind loads on thetower and ancillaries.

MStower computes and applies gust factors to member forces for thecases of wind on the bare equivalent tower, adds in the member forcesdue to gust wind on the ancillaries, and then recomputes the combinationcases.

Note: The above applies only where mean wind speeds are used. If gustwind speeds are used the loads on large ancillaries will be computedseparately and added to the loads on the equivalent bare tower beforeoutput. No additional sub-cases will be produced.

Ancillary LibrariesAncillary libraries are text files containing blocks of data giving thedimensions and drag characteristics of ancillary items. Separate librariesare used for large ancillaries and linear ancillaries. The libraries remaintext files and unlike the section library, do not require further processingbefore use.The libraries supplied with MStower are called Lin.LIB and Anc.LIB.Because of the wide variety of ancillaries, there is no doubt that you willhave to add additional information to the libraries. It is recommendedthat the distribution libraries are not modified. Instead, for each project,you may copy the distribution versions to libraries with names of yourchoice. All changes should then be made to the project libraries.

Note: Ancillary libraries use metric units.

The structure of an ancillary library file is:ANCILLARY

<geometric data for ancillaries>...

ENDCOEFFICIENTS

<drag and projected area coefficients>...

END


Large Ancillary LibraryThe ANCILLARY block in the large ancillary library contains thefollowing data for each ancillary type:name coeff dim mass af asf aice zref xcg xicg...

fcx fcy fzm ishape

where:name Name by which the antenna is referenced in the TWR file.coeff Name of set of coefficients to be used in calculating the

projected area and wind resistance of the antenna.dim Reference dimension, in m, normally the dish diameter, used in

computing forces and moments about the antenna axes and theBS 8100 gust factor for the antenna.

mass Mass of the ancillary, in kg.af Frontal area of the antenna, in m2.asf Side area of antenna, in m2. This will be used to compute the

projected area of the antenna at different angles if the projectedarea coefficients are zero. In this case, the projected area willbe computed as:af × cos²(angle) + asf × sin²(angle)

aice Surface area of a the antenna that may be coated with ice, inm2. Used in computing the weight of ice on an iced antenna.

zref Z dimension from the antenna origin for wind loads and thelevel of the antenna in the TWR file, in m. Usually, either thecenterline of radiation or the mounting level of the antenna.

xcg Horizontal offset from the antenna origin to the center ofgravity of the un-iced antenna, in m.

xicg Horizontal offset from the antenna origin to the center ofgravity of a uniform ice coating on the antenna, in m.

fcx Correction factor to be applied to drag coefficient for drag forcealong the axis of the antenna.

fcy Correction factor to be applied to drag coefficient for horizontaldrag force normal to the axis of the antenna.

fzm Correction factor to be applied to drag coefficient for yawingmoment (twisting about the vertical axis of the antenna).

ishape Shape code for the antenna, used to select a symbol forplotting.

The drag coefficients are contained in the ancillary library in a separateCOEFFICIENTS block, which may contain any number of sets ofcoefficients:COEFFICIENTS

coeff FACT factang afact Cfx Cfy Cfz Cmx Cmy Cmz...

END


where:coeff Name of set of drag and projected area coefficients.FACT Keyword.fact Factor by which the coefficients in the table must be multiplied

so that when used with kg and meter units, the resulting forcesand moments will be in N and N.m.

ang Angle of wind incidence for which drag coefficients apply.afact Area angle factor. The projected area on a plane normal to the

angle of wind incidence is obtained as:af × afact

Cfx Coefficient for drag along the “x” axis of the antenna.Cfy Coefficient for side force along the “y” axis of the antenna.Cfz Coefficient for lift force along the “z” axis of the antenna.Cmx Coefficient for moment about the antenna “x” axis, i.e. the

rolling moment.Cmy Coefficient for moment about the antenna “y” axis, i.e. the

pitching moment.Cmz Coefficient for moment about the antenna “z” axis, i.e. the

yawing moment.

The forces and moments at the origin of the antenna are given by:Fx = 0.5 ρ × Cfx × Af × V2

Fy = 0.5 ρ × Cfy × Af × V2

Fz = 0.5 ρ × Cfz × Af × V2

Mx = 0.5 ρ × Cmx × dim. × Af × V2

My = 0.5 ρ × Cmy × dim. × Af × V2

Mz = 0.5 ρ × Cmz × dim. × Af × V2

where “dim.” is a lever-arm.If necessary, the coefficients for the angle of wind incidence areinterpolated from the coefficients table. All dimensions and forces for anantenna are measured in the ancillary axes, a set of right-handedorthogonal axes (see diagram in “Ancillary Block” on page 126).


Linear Ancillary LibraryThe ANCILLARY block in the linear ancillary library contains thefollowing data for each ancillary:name coeff mass af asf

where:name Name by which the antenna is referenced in the TD file.coeff Name of set of drag curves to be used for the antenna. Use

NONE if the standard drag coefficients given in BS 8100 are tobe used.

mass Mass of the ancillary per unit length, in kg/m.af Frontal are of the antenna, in m²/m.asf Side area of antenna. This will be used to compute the

projected area of the antenna at different angles if the projectedarea coefficients are zero. In this case, the projected area willbe computed as:af × cos²(angle) + asf × sin²(angle)

aice Surface are of the antenna that may be coated with ice, in m²/m.Used in computing the weight of ice on an iced antenna.

shape An integer code indicating the ancillary shape. Used for theselection of standard drag coefficients and in computing thethickness of ice coating:0 = Cylindrical.1 = Sharp-edged flat section.

Drag CoefficientsThe drag coefficients are contained in the ancillary library in a separateCOEFFICIENTS block, which may contain any number of sets ofcoefficients:COEFFICIENTS

coeff FACT factang afact Cfx Cfy...

END

where:coeff Name of set of drag and projected area coefficients.FACT Keyword.fact Factor by which the coefficients in the table must be multiplied

so that when used with kg and meter units, the resulting forcesand moments are in N and N.m.

ang Angle of wind incidence to which drag coefficients apply.afact Area angle factor. The projected area on a plane normal to the

angle of wind incidence is obtained as:af × afact


Cfx Coefficient for drag along the “x” axis of the ancillary.Cfy Coefficient for side force along the “y” axis of the ancillary.

The forces and moments at the origin of the ancillary are given by:FX = 0.5 ρ × Cfx × Af × V²FY = 0.5 ρ × Cfy × Af × V²If necessary, the coefficients for the angle of wind incidence areinterpolated from the coefficients table. All dimensions and forces for anantenna are measured in the ancillary axes, a set of right-handedorthogonal axes (see diagram in “Ancillary Block” on page 126).

MSTower V5 10:CAD Interface • 143

10:CAD Interface

GeneralThe CAD Interface is an integral part of MStower that offers thecapability of exporting 3-D data to a CAD system, forming the basis fora CAD drawing. This function is selected with the File > Export > CADDXF command. Structure information is exchanged by means of anAutoCAD DXF.

Note: You can use the Windows Paste command to transfer any part ofan MStower image into CAD.

Exporting a CAD DXFEach member center-line is represented by a single LINE entity in theDXF. The section shape may also be represented by a number of planes.The section shapes may be curtailed at member ends to avoidoverplotting at the intersections.On selecting the File > Export > CAD DXF command the dialog boxbelow is displayed.

CAD DXF EXPORT PARAMETERS

144 • 10:CAD Interface MSTower V5

The DXF contains only an Entities section without a drawing header. InAutoCAD, you may import the file with the “DXFIN” command andthen use the “ZOOM E” command to fill the screen with the drawing.The limits may then be adjusted as required.You may suppress hidden lines and render the drawing in AutoCAD.

Exporting a Steel Detailing Neutral FileSelect File > Export > SDNF to create a file that can be imported into asteel detailing program that recognizes the SDNF format (e.g. Xsteel).The file will be created in the data folder with the name Job.SDN, where“Job” is the MStower job name. At present, this command will transferonly the structural geometry and section sizes to the SDN file.

Windows Clipboard OperationsMStower facilitates use of the Windows clipboard for transfer of imagesto CAD programs by using the Enhanced Metafile Format (EMF) for theWindows clipboard when you select the View > Copy command. Inprograms such as AutoCAD, you can then use the Paste command todirectly insert an image of the main MStower view. Pressing the PrintScreen key on the keyboard writes a Windows bitmap to the clipboard.Both of these formats may be pasted into Microsoft Word documents.

MSTower V5 11:Analysis • 145

11:Analysis

GeneralMStower offers a number of static and dynamic analysis options, each ofwhich employs exhaustive consistency checking and highly efficientequation solution procedures. The analysis engines used in MStower arederived from those used in Microstran, a widely-used and extremelyversatile program for analysing and designing structural frameworks insteel and reinforced concrete.Linear Elastic Analysis is a first-order elastic static analysis in whichnon-linear effects are ignored and the stiffness equations are solved foronly the primary load cases. Solutions for combination load cases areobtained by superposition of the solutions for the primary load cases.Non-Linear Analysis is a second-order elastic analysis, which enablesyou to take into account the non-linear actions arising from thedisplacement of loads (the P-∆ effect), the change in flexural stiffness ofmembers subjected to axial forces (the P-δ effect), and the shortening ofmembers subjected to bending (the flexural shortening effect). Non-linear analysis is an iterative procedure in which the behaviour at eachstep is controlled by a number of parameters. Each selected case,whether a primary or combination load case, must be solved separately,as superposition of results cannot be used. Members defined as tension-only will be checked at each iteration and included or excludedaccordingly.Elastic Critical Load Analysis calculates the frame buckling loadfactor, λc, for selected load cases and computes the correspondingmember effective lengths for each load case.Dynamic Analysis computes the natural vibration frequencies of thestructure and the associated mode shapes. The dynamic loads on thestructure due to earthquake or other support acceleration may then beassessed using the response spectrum method.The Profile Optimizer is used in all analyses to minimize analysis timeand storage requirements. Nodes and members can therefore benumbered for maximum convenience in data generation andinterpretation of results.

146 • 11:Analysis MSTower V5

MethodMStower uses the well-documented direct stiffness method of analysis inwhich the global stiffness matrix, [K], is assembled from the stiffnesscontributions of individual members. For large structures, [K] can bequite large and is stored on disk in blocks sized to maximize the use ofavailable memory and to minimize solution time. Load vectors, P, areformed from the applied loads and node displacements, u, aredetermined by solving the equation:P = [K] u The forces in each member are then determined by multiplying themember stiffness matrix by the appropriate terms of the displacementvector, resolved into member axes.

Consistency CheckMStower performs an automatic check of all input data prior to analysis.The consistency check will detect a range of modelling problems relatedto geometry and loading. Data errors and warnings are shown in theOutput window and are also written to the error report, which can belisted and printed using options on the File menu.

AccuracyAll analyses use double-precision arithmetic to minimize the loss ofprecision inherent in the many arithmetic operations required for solvinglarge, complex structural models. After the decomposition of the [K]matrix MStower reports the maximum condition number, a measure ofthe loss of precision that has occurred during the solution. For “well-conditioned” structural models (those in which little numerical precisionis lost) the condition number will be less than 104. If the conditionnumber exceeds this value you should treat the results with caution andlook for evidence of “ill-conditioning”. For example, the largedisplacement of a node or group of nodes may indicate that the structureis acting, to some extent, as a mechanism, and the results could bemeaningless.An important independent check on the accuracy of the solution isprovided by the node equilibrium check. At unrestrained nodes the sumof all the member end actions is compared to the sum of external forcesacting on the node. Any difference is a force residual, the out-of-balanceforce. The maximum residual is reported to the screen after the analysis.The maximum residual should be considered in conjunction with themagnitudes of the applied loads in assessing the adequacy of thesolution.

Note: A satisfactory equilibrium check, by itself, is not sufficient toensure an accurate solution – the condition number must also besatisfactory.


MStower will choose the appropriate method of analysis when Tower >Analyse is selected. Linear analysis will be used unless the towercontains tension-only members or guys (cables).

Linear Elastic AnalysisLinear elastic analysis cannot be performed if there are any tension-onlyor cable members in the model. An error message will be displayed ifyou attempt linear analysis of a model containing these member types.All load cases are analysed when you choose linear analysis. Results forcombination load cases are determined by superposition of the results ofthe component primary load cases.

Note: If you perform a non-linear analysis and then a linear analysis, thesettings in the Select Analysis Type dialog box will be lost (see“Selecting Load Cases for Non-Linear Analysis” on page 148).Performing a linear analysis sets the analysis type flag to L (linear).

Non-Linear Analysis

Non-Linear Analysis (also called second-order analysis) performs anelastic analysis in which second-order effects may be considered. Thedifferent second-order effects are described below.Non-linear analysis uses a multi-step procedure that commences with alinear elastic analysis. The load residuals, computed for the structure inits displaced position and with the stiffness of members modified, areapplied as a new load vector to compute corrections to the initialsolution. Further corrections are computed until convergence occurs.There is no single method of iterative non-linear analysis for whichconvergence is guaranteed. It may therefore be necessary to adjust theanalysis control parameters in order to obtain a satisfactory solution.The solution may not converge if the structure is subject to grossdeformation or if it is highly non-linear. This may be the case as theelastic critical load is approached.

Note: You should not attempt to use non-linear analysis to determineelastic critical loads. Results of non-linear analysis should be treatedwith caution whenever the loading is close to the elastic critical load.


Second-Order EffectsThe most important second-order effects taken into account in non-linearanalysis are the P-Delta effect (P-∆) and the P-delta effect (P-δ). Theseare discussed in detail below.

P-∆ AND P-δ EFFECTS

You may independently include or exclude these two major effects.Different combinations of the P-∆ and P-δ settings affect the operationof non-linear analysis as set out in the table below.

NodeCoordinateUpdate

AxialForceEffects

Analysis Type

NO NO Linear elastic analysis with tension-only orcompression-only members taken intoaccount. This can be achieved for any loadcase by selecting linear analysis

YES NO Analysis includes the effects ofdisplacement due to sidesway but notchanges in member flexural stiffness due toaxial force. These settings will usuallyyield satisfactory results for pin-jointedstructures.

NO YES Full account is taken of the effects of axialforce on member flexural stiffness whilethe effects of node displacement areapproximated by a sidesway correction inthe stability function formulation. Thesesettings normally give minimum solutiontime with second-order effects taken intoaccount.

YES YES This is the default analysis type, whichprovides the most rigorous solution for allstructure types.


Node Coordinate Update – P-Delta EffectThe P-Delta effect (P-∆) occurs when deflections result in displacementof loads, causing additional bending moments that are not computed inlinear analysis. P-∆ is taken into account either by adding displacementcomponents to node coordinates during analysis or by adding sideswayterms to the stability functions used to modify the flexural terms in themember stiffness matrices. Either small displacement theory or finitedisplacement theory may be used with node coordinate update. Asshown in the diagram below, finite displacement theory takes intoaccount the rotation of the chord of the displaced member in computingthe end rotations and the extension of the member. Only where largedisplacements occur would the use of finite displacement theory produceresults different from those obtained with small displacement theory.

SMALL AND FINITE DISPLACEMENT THEORIES

Axial Force Effects – P-delta EffectThe bending stiffness of a member is reduced by axial compression andincreased by axial tension. This is called the P-delta effect (P-δ) and istaken into account by adding beam-column stability functions to theflexural terms of the member stiffness matrices. Member stiffnessmatrices therefore vary with the axial load and are recomputed at everyanalysis iteration. The stability functions are derived from the “exact”solution of the differential equation describing the behaviour of a beam-column. The additional moments caused by P-δ are approximated insome design codes by the use of moment magnification factors appliedto the results of a linear elastic analysis.

Changes in Fixed-End ActionsMember fixed-end actions may change between successive analysisiterations owing to displacement of the member and variations in its


flexural stiffness caused by axial force. MStower automaticallyrecalculates the fixed-end actions at each analysis iteration and updatesthe load vector accordingly.

Non-Linear MembersAnalysis of structures containing tension-only, or cable membersrequires non-linear analysis. At the conclusion of each analysis step, allmembers nominated as tension-only or compression-only are checkedand either removed from or restored to the model for the next analysisstep, according to their deformation. If the removal of non-linearmembers causes the structure to become unstable, no solution ispossible.

Running a Non-Linear AnalysisSelecting Load Cases for Non-Linear AnalysisNon-linear analysis lets you specify the load cases to be analysed and theanalysis type (linear or non-linear) to be used for each.For non-linear analysis a load vector is formed for each load case to besolved, whether a primary load case or a combination load case. There isno need to analyse any load cases for which results are not required.On selecting the Analyse > Non-Linear command, the following dialogbox is displayed so you may specify the load cases to be analysed andthe analysis type. In the Type column, load cases are identified asPrimary or Combination. The second character is a code that specifieswhether the load case is to be processed with Linear analysis or Non-linear analysis, or is to be ignored (Skipped).

SELECTING LOAD CASESFOR NON-LINEAR ANALYSIS

The ability to use different analysis types is used for obtaining results forboth linear and non-linear analysis in a single pass. This may benecessary where the model includes members to be designed to differentcodes with different analysis requirements.In general, only “realistic” load cases should be selected for non-linearanalysis – there is no point in analysing a wind load case because this


load will never exist in isolation. This is particularly important forstructures containing cable elements where realistic loads including selfweight are required to determine the equilibrium position of each cable,and a solution may not be possible for load cases containing only someload components.

Note: The settings in this dialog box will be lost if you subsequentlyperform a linear analysis. In this case, the analysis type flag (S/L/N) willbe unconditionally set to Linear. You must reinstate the analysis typeflag if you revert to non-linear analysis.

Non-Linear Analysis ParametersThe next dialog box determines the type of non-linear analysis that willbe performed for load cases selected for non-linear analysis.

.

NON-LINEAR ANALYSIS PARAMETERS

The dialog box contains the following items:• Node coordinate update (P-∆)

This flag is set if node coordinates are to be updated at each analysisstep. It is automatically set for structures containing cable elements.The default setting is on.

• Small/finite displacement theoryIf the node coordinate update flag has been set, either small or finitedisplacement theory must be selected. Small displacement theory isthe default setting.

• Axial force effects (P-δ)If this flag is set member stiffnesses are modified at each analysisstep. The default setting is on.

• Residual / displacementSpecifies the criterion to be used for convergence of the solution.Residual uses a function of the maximum out-of-balance force afteranalysis. When Displacement is selected, convergence is checked bycomparing the convergence tolerance against a generalized measureof the change in displacement between successive iterations. For asatisfactory solution there must be acceptably small changes in the


displacement and the residual must be of a low value. The defaultsetting is Residual.

• Displacement controlIncreasing the setting of this control will assist convergence insituations where displacements appear to diverge with successiveanalysis iterations, or for structures that are initially unstable butbecome stable as they displace under load. You normally leave thiscontrol at minimum and only increase the setting if difficulties areencountered in solution.

• Convergence toleranceThis value determines when the analysis has converged, determinedby checking the change in the convergence criterion betweensuccessive analysis cycles. Too small a value will prolong thesolution time and may even inhibit convergence. The default valueis 0.0005.

• No. load stepsYou may apply loads in a stepwise fashion which may assist inobtaining a solution for flexible structures by keeping displacementssmall at each load increment. This parameter is usually left at itsdefault value of 1.

• Iterations per load stepThe maximum number of analysis iterations for each load step. Thisparameter is used to stop the analysis if convergence is taking anexcessive time. The default value is 50, but larger values are oftenapplicable for very flexible structures or models containing largenumbers of cable elements.

• Relaxation factorThe relaxation factor is applied to incremental displacementcorrections during analysis. The optimum value for the relaxationfactor depends on the type of the structure. As a general rule,structures which “soften” under load (i.e., displacements increasedisproportionately with load) have an optimum relaxation factorbetween 1.0 and 1.2 while structures which “harden” under loadhave an optimum relaxation factor as low as 0.85. Caution isrecommended in changing the relaxation factor from the defaultvalue of 1.0; if the relaxation factor is too far from optimum theanalysis may require an excessive number of iterations forconvergence or it may not converge at all.

• Oscillation controlThis control facilitates convergence when the solution oscillatesowing to the removal and restoration of tension-only orcompression-only members. The default setting is off.

As the analysis proceeds, the analysis window displays key informationfor each selected load case. At each analysis iteration the maximumvalues of residual and displacement are displayed in correct user units.Note that at this stage the values shown are from the most critical degree


of freedom, i.e., residuals may be either forces or moments, anddisplacements may be either translations or rotations.


Troubleshooting Non-Linear AnalysisIt is possible to perform a successful linear analysis for structures thatare incapable of resisting the imposed loads. Non-linear analysis is amore complete simulation of the behaviour of a structure under load andthe procedure may fail to provide a solution where a linear analysissucceeds. This may occur, for example, if some compression membersare slender and buckle. Where non-linear analysis fails to converge, thefollowing tips may be helpful:• Make sure that a linear analysis can be performed. If not,

troubleshoot the linear analysis before continuing with the non-linear analysis.

• Is a full non-linear analysis necessary? If the only significant non-linear effect is the presence of tension-only or compression-onlymembers, set the analysis type to L for these load cases. In othercases, a successful analysis may result if either node coordinateupdate or axial force effects are excluded.

• Examine the analysis log file. It contains information aboutmembers that have become ineffective because of slenderness ormember type.

• Perform an elastic critical load analysis to check the frame bucklingload. If it is greater than the imposed load non-linear analysis is notpossible.

• Is the structure too flexible? Remove excessive member end releases(pins). Sometimes, in diagnosing convergence problems, it is helpfulto remove ALL releases and reinstate them in stages.

• Adjust non-linear analysis parameters.

InstabilityInstability detected during linear analysis is usually due to modellingproblems and some of the common causes of these are discussedelsewhere.Because a non-linear analysis considers the effects of axial force onmember stiffness it is able to detect a range of instability that linearanalysis cannot. For example, non-linear analysis may detect buckling ofindividual members or of the whole frame. The manner in which astructure is modelled and the analysis parameters used can have somebearing on the stage of the analysis when instability of individualmembers is detected and the way in which it is subsequently treated. Ifan unstable member is detected during the update process at the end ofeach iteration, it will be deleted from the following iteration in much thesame way that a tension-only member would be. The presence ofunstable members is reported in the Analysis window and details arewritten to the static log file. However, if the instability is not in a singlemember but localized in a small group of members it may not bedetected until the completion of the analysis. In this case, the presence of


the instability will be reported in the Analysis window and somediagnostic information will be written to the static log file to assist youin correcting the problem. Even though the analysis has failed, resultsare available and may be used to determine corrective measures, e.g.increase some member sizes or, perhaps, change to tension-onlymembers. The results of an analysis in which instability has beenreported are useful for diagnosis but should not be used for otherpurposes.An elastic critical load analysis will often assist in locating the cause oflocal instabilities.

Elastic Critical Load AnalysisElastic Critical Load (ECL) Analysis (also referred to as stability, orbuckling analysis) performs a rational buckling analysis of the model tocompute the elastic critical load factors (λc) and the associated bucklingmodes. Member effective lengths can also be determined from the elasticcritical load.The buckling behaviour depends on the distribution of loading on theframe and buckling parameters are computed separately for each loadcase to be considered. The buckling load factor for any load case is thefactor by which the axial forces in all the members must be multiplied tocause the structure to become unstable (lateral torsional buckling ofindividual members is not taken into account). The elastic critical load ofthe structure is a function of the elastic properties of the structure and thepattern of loading.The effective length of a member is defined as the length of an ideal pin-ended strut whose Euler load is the axial load in the member when thestructure is at its critical load. The effective length may be expressed as afactor multiplying the actual member length (k). The effective lengthfactor is calculated separately for each of the member principal axes foreach load case. A load factor of less than 1.0 for any load case indicatesthat the structure is unstable under the applied loading.A linear elastic analysis is often used for the initial analysis, but non-linear analysis must be used when the structure contains non-linearmembers. For most structures the load factor will not be influencedgreatly by the type of initial analysis and a linear analysis isrecommended in order to reduce the overall solution time.Restraints affecting the flexural buckling behaviour of the structure mustbe included in the structural model. For example, if out-of-planebuckling behaviour is to be considered for a plane frame, the framewould have to be modelled as a space frame with nodes located at thepositions of lateral restraints (restraint can be introduced only at nodes). Elastic critical load analysis is not recommended for structurescontaining cable elements because of the highly non-linear nature ofstructures of this type.


Selecting Load Cases for ECL AnalysisSelect Analyse > Elastic Critical Load from the main menu. The dialogbox below is displayed for you to select the required load cases. Usually,only combination load cases required for design are selected.

SELECTING LOAD CASESFOR ECL ANALYSIS

Analysis Control ParametersAfter selecting load cases, the dialog box shown below appears. Thesettings in this dialog box determine the type of elastic critical loadanalysis that will be performed.

ECL ANALYSIS PARAMETERS

The dialog box contains the following items:• Initial analysis

The initial analysis determines the distribution of axial forces to beused for the elastic critical load analysis. It is normally Linear butshould be Non-linear if the structure contains tension-only,compression-only, or cable members.

• ToleranceThe tolerance is the relative accuracy to which the load factor isrequired. Too small a value will prolong the solution time. Thedefault value is 0.01.

• Max. load factorThe search for the elastic critical load will terminate if the loadfactor exceeds this limiting value. The default value is 1000.


• No. modesThe number of buckling modes to be computed for each selectedload case. Normally, only the first mode is required, though highermodes may be of interest if lower modes are inhibited or representlocalized buckling behaviour.

When the analysis is finished a summary of results appears in theanalysis window. The summary shows for each selected load case thecritical load factor and the most critical member with associated kvalues.

Why ECL Analysis Sometimes Gives High kFactorsThe effective length of a given member in a frame is the length of anequivalent pin-ended member whose Euler load equals the buckling loadof the frame member. The effective length factors, kx and ky, are factorsby which we multiply the actual length of the member in order to obtainthe effective lengths for buckling about the section XX and YY axes,respectively. When designing the frame member by traditional methods,we take account of the stiffness of connected members to obtain theeffective length and then we consider it as if it were an isolated memberof an appropriate length. We could then determine the axial loadrequired to cause column buckling in this equivalent member.ECL analysis allows us to determine the frame buckling load factor for agiven load case. Frame buckling occurs when the axial forces for thegiven load case are factored to the point where the frame collapses.Display the buckling mode shape of the frame and you can see how theframe buckles. Frame buckling for a given load case is usually acomplex interaction of several members – there is not necessarily anyone member that causes the buckling of the frame. In this situation, if weapply our definition of effective length, we find that the effective lengthof a given member for a given load case is the length of an equivalentpin-ended member whose Euler load equals the load in that memberwhen frame buckling occurs. Thus, any member carrying a small axialload at frame buckling will have a large effective length. Also, theeffective length of a member will vary from one load case to another. Itis only where a member could be said to be critical (i.e. participating to avery large degree in the buckling mode), that the effective length factorcould be compared with the value used in traditional methods.In general, traditional effective length factors relate to the buckling loadof the member being considered whereas the effective length factorcomputed by ECL analysis relates to frame buckling.

Dynamic AnalysisDynamic Analysis computes the frequencies and mode shapes of thenatural vibration modes of the structural model. Only the mass and

http://www.microstran.com/as1170_4.htm

http://www.microstran.com/nzs4203.htm


stiffness of the model are considered in computing natural frequenciesand mode shapes. Static load cases are ignored. The frame mass iscomputed automatically and additional mass that is to be taken intoaccount may be modelled as node masses. Member masses are computedautomatically as the product of the cross-sectional area and the massdensity. Additional node masses may be input as required. The unit usedfor mass must be consistent with the force and length units.Select the Analyse > Dynamic command to start dynamic analysis.

Analysis Control ParametersAfter selecting load cases, the dialog box shown below appears. Thesettings in this dialog box determine the type of dynamic analysis thatwill be performed.

DYNAMIC ANALYSIS PARAMETERS

The dialog box contains the following items:• No. modes

The number of natural frequencies and mode shapes that can becomputed is limited by the number of dynamic degrees of freedom,and, for large structures, by the amount of available memory.Solving for a large number of modes is usually not warranted.

• ToleranceThis is the tolerance to be used in determining the convergence ofeigenvalues. If the value is too small, convergence may not bepossible or an excessive number of iterations may be required. If thevalue is too large, the eigenvalues found may not be the lowest. Thedefault value is 0.00001.

• Verify eigenvaluesCheck this box if you wish to verify that no eigenvalues have beenskipped in the computation (see above).

• Lumped mass / Consistent massThe mass matrix may be computed using either a consistent mass orlumped mass formulation. The consistent mass matrix has a firmertheoretical basis but gives rise to a global mass matrix that is similarin shape and size to the global stiffness matrix, requiring greaterstorage and computational effort than the lumped mass matrix,which leads to a diagonal global mass matrix

• Initial state load caseNon-linear behaviour is not taken into account in dynamic analysis


but it is possible to specify a load case that defines the initial state.For example, a leeward cable in a guyed mast subjected to windload may be slack. If the corresponding load case is specified as theinitial state load case, the slack cable will be eliminated from theanalysis. The default value is zero.

• Response spectrum analysisYou must check this box if you wish to proceed to a responsespectrum analysis after the dynamic analysis.

Dynamic ModesAfter completing a dynamic analysis it is important to check the modeshapes to ensure that you have the required dynamic modes. MStowercomputes all dynamic modes, including torsional modes. The easiestway to examine the results is to display an animated view of thecomputed mode shapes.

Note: You can add low-mass “semaphore” members to visualisetorsional modes.

Dynamic Analysis ExampleThe diagram below shows the mode shape computed for the first modein dynamic analysis of the TWEX5 example.

NATURAL MODE SHAPE


Response Spectrum AnalysisThe Response Spectrum Analysis is used to determine peakdisplacements and member forces due to support accelerations using theresponse spectrum method. The spreadsheets As1170_4.XLS (seehttp://www.microstran.com/ftp/as1170_4.htm) and Nzs4203.XLS (seehttp://www.microstran.com/ftp/nzs4203.htm) set out detailed proceduresfor performing response spectrum analysis complying with the designcodes AS 1170.4 and NZS 4203, respectively.

Running a Response Spectrum AnalysisThe procedure for performing a response spectrum analysis is:1. Set up static analysis load cases and perform the static analysis. The

earthquake load cases are empty – results from the responsespectrum analysis will be added automatically.

2. Select dynamic analysis and check Response spectrum analysis.

3. You are next prompted to identify the load cases that are to be usedfor the results of the response spectrum analysis. There will be onesuch load case for each earthquake direction being considered.

4. For each earthquake load case you must enter parameters todetermine the response spectrum direction and the number of modesto be considered. The direction factors determine the direction of thesupport acceleration in terms of components in the global axisdirections. These components will be reduced to a unit vector beforebeing used. The number of modes must be sufficient to satisfy theearthquake code requirement that 90% (typically) of the seismicmass is accounted for. It must not be greater than the number ofmodes computed during dynamic analysis (Step 2, above).


5. For each earthquake load case damping ratios are specified. The“Complete Quadratic Combination” method (CQC) for combiningmodal responses is used to determine the peak response. This isequivalent to the “Square Root of the Sum of Squares” (SRSS)method if all modal damping ratios are zero.

6. For each earthquake load case a response spectrum curve andscaling factor must be specified. The response spectrum curve ischosen from a list of names of digitized response spectrum curvescontained in file Response.TXT (described below). You may editthe response spectrum curves or add new ones using the Configure> Edit Response Spectra command.

7. After Steps 3-6 have been completed for each earthquake case, thedynamic analysis proceeds. On completion, select the Analyse >Response Spectrum command to scale the computed actions andcombine them with the static analysis results (note that this item isgreyed out on the menu until all the necessary preconditions forresponse spectrum analysis have been completed). The totalreactions (base shears) are displayed for each earthquake case andyou now enter scale factors for each case. The spreadsheets referredto above will assist you in computing scale factors to comply withcode requirements.


MStower now adds the results from the response spectrum analysis tothe static analysis results. Earthquake load cases may now be treated asany other load case for the display and reporting of results and fordesign.

Note: The displaced shape represents the peak values of thedisplacement during the earthquake event. There are no negative values.Interpretation of the results should take this into account.

Response Spectrum Scale FactorThe scale factor used in Step 6, above is used to multiply the spectralacceleration values to give the actual support acceleration to be used inthe analysis. Many codes give spectral accelerations in a normalizedform that have to be multiplied by site acceleration factors. Forconvenience, file Response.TXT uses normalized spectral values.The results of the static analysis are updated with the results of theresponse spectrum analysis. As this process takes place, the sum of thereactions for each dynamic load case will be displayed and you mayenter factors that will be used to scale the results to ensure compliancewith codes that require minimum base shears (Step 7, above). The factorshould be based on the base shear in the direction of the supportacceleration. Note that the values given for the reactions are the sum ofabsolute values, as the methods used to combine individual modalresponses result in loss of sign.The results for each dynamic load case are inserted in the results files forthe previously defined empty load cases. Any combination case thatrefers to the dynamic case is updated by adding the specified dynamiccase, factored as specified. By updating combination cases instead ofcomputing them completely from the results of primary cases, any non-linearity in the previously computed results is preserved. However, thestatic analysis must be repeated if the dynamic analysis is to beamended.

Note: After running response spectrum analysis you should look at thedynamic analysis log file, which contains important data including massparticipation factors.


Response Spectrum CurvesThe digitized data for the response spectrum curves must be entered intothe Response.TXT file, which resides in the library folder. This is a textfile that may be edited by the user to add additional response spectrumdata. The format of each set of data in the file is as follows:NameT(1) Sa(1)T(2) Sa(2)T(3) Sa(3).....T(n) Sa(n)END

where: Name String of alphanumeric characters used to identify each curve.T(n) Period in seconds for the nth point on the curve.Sa(n) Spectral acceleration for the nth point on the curve. The spectral

accelerations may be in normalized form or as absoluteaccelerations with a scale factor, described previously, being usedto effect any required conversion.

END Keyword indicating the end of data for this curve.


ErrorsThere are some types of error that only become evident during analysisand it is not possible for the consistency check to warn of this type oferror before the analysis commences. For example, if a structure isunstable because some part of it actually forms a mechanism, analysiswill be terminated and an error message will be displayed on the screen.The error message is of the form:STRUCTURE UNSTABLE AT NODE nnnnn DOF f

where:nnnnn = The node number at which instability was detected.f = The DOF number, as shown in the table below, in which there

was found to be no resistance to displacement.

Sometimes in linear elastic analysis a modelling problem may manifestitself as gross linear or angular displacement. This kind of problem maynot be obvious in the member force plots but may be evident in the plotof displaced shape. Modelling problems of this type can usually be fixedby the addition of one or more node restraints to inhibit the grossdisplacement.In non-linear analysis very large displacements can occur in the analysisof structures containing very flexible tension members. If displacementsare sufficiently large the analysis will be terminated with a message ofthe form:EXCESSIVE DISPLACEMENTS

A solution can sometimes be obtained in cases like this by adjusting theanalysis parameters but it is preferable to model very flexible tensionmembers as cables.The above error message may also be obtained where the automaticdeletion of tension-only bracing members during non-linear analysisrenders a structure unstable.


MSTower V5 12:Member Checking • 167

12:Member Checking

GeneralThis chapter describes the MStower modules for checking the strengthof members in latticed towers and masts in accordance with the rules setout in the following codes:• BS 8100:Part 3 (DD 133:1986)• BS 449• AS 3995-1994• ASCE 10-90 1991• EIA-222-F-1996The member checking modules use data generated by the tower builder,loading modules, and the results of the static analysis.

OperationStart the code checking module by selecting the appropriate code fromthe Member Check menu.The report may be limited by selecting classes of members to be checkedand setting the report limit on the ratio of design load/capacity.Two forms of report are produced, a summary report and a detailedreport. They may be viewed or printed by selecting File > List/Edit andFile > Print, respectively.The load/capacity ratios (stress ratios for BS 449) may be displayedgraphically by selecting Results > Design Ratios.

168 • 12:Member Checking MSTower V5

Design LoadsAxial loads are taken from the results of the analysis (and anysubsequent gust-factoring) for legs, braces, and horizontals.Members such as face redundants and hip and plan bracing normallystabilize the load carrying members of the structure and usually attractsmall or negligible analysis forces. These are designed using the greaterof:• The force computed from the analysis.• 2.5% (1.5% for EIA-222-F) of the axial force in the members they

stabilize.

Member Checks to BS 8100: Part 3 (DD 133)Code TypeBS 8100 is a limit states code. The capacity of members at the strengthlimit state is checked.Structural Configuration and Buckling LengthsMStower uses output from the tower builder (in which the tower data isassembled from a list of panel types and dimensions) to determine thenature of a member and its configuration related to the rules set out inSection 5 of DD 133 to determine buckling lengths.If the face has cross-bracing that is not braced against out-of-planebuckling, the forces in both diagonals are determined so that the criticalL/r ratios and design capacities may be assessed in accordance with Cl.5.3.3 of DD 133.Selection of Buckling CurvesBuckling curves are selected in accordance with the rules in Section 6.5of DD 133, using member classification and continuity informationgenerated during tower building. Unless otherwise specified in the towerdata file, the checking module assumes that legs, braces, and horizontalsare connected with two or more bolts and that redundants and plan andhip bracing are connected with single bolts.Calculation of Ultimate Member StressesThe ultimate stress of the member is calculated from the rules in Section6 of DD 133. If the section is not one tabulated in DD 133 the referencestress is determined by application of the rules for hot-rolled angles toany elements of the section that have an unsupported free edge.BoltsBolts are checked for shear on the bolt and bearing on the member usingthe rules in accordance with Section 9. If any of the dimensions x, y, andz are not specified or set to zero, the checking module assumes that these


are equal to or greater than the minimums specified in the code to allowan ultimate bearing strength of 2.0 × (D.T.fy) to be attained.ReportFor each panel in the tower, the report lists the member number, theclassification (leg, brace, etc.), the section size and yield strength, themost critical load case, the sub-clause of DD 133 Section 6.5 used inselecting the buckling curve, the slenderness ratio, and whether it isabout the x-x, y-y, v-v axes, the axial design force, the capacity and theratio of design load to capacity.An expanded version of the report, more suitable for detailed checkingof the results for particular members is available. This report may bequite large.RestrictionsThis version of MStower has the following restrictions:• Members are checked for axial force only.• No check is made on “man-load” on horizontal or nearly horizontal

members.The value of K used in computing the non-dimensional slenderness oftubular members is taken as 1.0.

Member Checks to BS 449Code TypeBS 449 is a permissible stress design code. The stresses in members atservice conditions are checked.Structural Configuration and Buckling LengthsMStower uses output from the tower builder (in which the tower data isassembled from a list of panel types and dimensions) to determine thenature of a member and its configuration related to the end boltingarrangement to determine effective length factors.Calculation of Permissible Member StressesThe permissible stress in the member is calculated from the formulae inAppendix B of BS 449, with a user-supplied wind overstress factorapplied if the member forces due to wind loads increase the memberforces due to other causes.BoltsAt present, bolted joint checks are not implemented for this code.ReportFor each panel in the tower, the report lists the member number andclassification (leg, brace, etc.), the section size and yield strength, themost critical load case, the effective length factor, the slenderness ratioand whether it is about the x-x, y-y, v-v axes, the axial design force, the


actual and permissible stresses (and whether a wind overstress factor isincluded), and the ratio of the actual to permissible stresses.An expanded version of the report more suitable for detailed checking ofthe results for particular members is available. This report may be quitelarge.RestrictionsThis version of MStower has the following restrictions:• Members are checked for axial force only.• No check is made on “man-load” on horizontal or near-horizontal

members.• Joint capacities are not checked.

Member Checks to AS 3995Code TypeAS 3995 is a limit states code. The capacity of members at the strengthlimit state is checked.Structural Configuration and Buckling LengthsMStower uses output from the tower builder (in which the tower data isassembled from a list of panel types and dimensions) to determine thenature of a member and its configuration related to the rules set out inAppendix H of AS 3995 to determine buckling lengths.If the face has cross-bracing that is not braced against out-of-planebuckling at the intersection point, the forces in both diagonals aredetermined so that the critical L/r ratios and design capacities may beassessed in accordance with Figure H2 of AS 3995.Effective Slenderness RatioEffective slenderness ratios are determined in accordance with Section3.3.4 of AS 3995, using member classification and continuityinformation generated during tower building. Unless otherwise specifiedin the tower data file, the checking module assumes that legs, braces, andhorizontals are connected with two or more bolts and that redundantsand plan and hip bracing are connected with single bolts.Calculation of Ultimate Member StrengthThe capacity of a member is calculated from the rules of Section 3.3 forangles in compression and with AS 4100 for other sections incompression and all sections in tension.BoltsBolted are checked for shear and bearing using the rules of AS 3995 Cl.3.5.4. No checks are made on the detailed requirements of Cl. 3.5.4.6.


ReportFor each panel in the tower, the report lists the member number, theclassification (leg, brace, etc.), the section size and yield strength, themost critical load case, the sub-clause of Section 3.3.4 of AS 3995 usedin determining the effective slenderness ratio, the effective slendernessratio and whether it is about the x-x, y-y or v-v axes, the axial designforce, the capacity, and the ratio of design load to capacity.

NOTE: In conformity with common international practice, therectangular axes for ALL sections are nominated as x-x and y-y. Forsymmetrical sections these axes are also the principal axes. For anglesthe minor principal axis is nominated as v-v.

An expanded version of the report more suitable for detailed checking ofthe results for particular members is available. This report may be quitelarge.RestrictionsThis version of MStower has the following restrictions:• Members are checked for axial force only.• No check is made on “man-load” on horizontal or nearly horizontal

members.

Member Checks to ASCE 10-90 1991Code TypeASCE 10-90 is a limit states code. The stresses in members at thestrength limit state are checked.Structural Configuration and Buckling LengthsThe checking module uses output from the tower builder (in which thetower data is assembled from a list of panel types and dimensions) todetermine the nature of a member and its configuration related to therecommendations set out in the Commentary to the ASCE “Guide forDesign of Steel Transmission Towers” – Second Edition (1988), todetermine buckling lengths.If the face has cross-bracing that is not braced against out-of-planebuckling at the intersection point, the forces in both diagonals aredetermined so that the critical L/r ratios and allowable stresses may beassessed in accordance with Example 7 of the design guide.Effective Slenderness RatioEffective slenderness ratios KL/r are determined in accordance withSection 5.7.4 of ASCE 10-90, using member classification andcontinuity information generated during tower building. Unless


otherwise specified in the tower data file, the checking module assumesthat legs, braces, and horizontals are connected with two or more boltsand that redundants and plan and hip bracing are connected with singlebolts.Calculation of Allowable StressesThe allowable stresses are calculated from the rules of Section 5.6 forcompression members and Section 5.10 for tension members. Flexuralstresses are not checked.BoltsBolts are checked for shear and bearing in using the rules of Cl. 6.3.2and Cl. 6.4. No checks are made on edge distance or spacingrequirements.ReportFor each panel in the tower, the report lists the member number, theclassification (leg, brace, etc.), the section size and yield strength, themost critical load case, the sub-clause of Section 5.7.4 of ASCE 10-90used in determining the effective slenderness ratio, the effectiveslenderness ratio, and whether it is about the x-x, y-y or v-v axes, theaxial design force, the capacity and the ratio of design load to capacity.An expanded version of the report more suitable for detailed checking ofthe results for particular members is available. This report may be quitelarge.RestrictionsThis version of member checking to ASCE 10-90 has the followingrestrictions:• Members are checked for axial force only.• No check on “man-load” on horizontal or nearly horizontal

members is made.

Member Checks to EIA-222-F 1998Code TypeEIA-222-F is an allowable stress code. The stresses in members underservice loads are checked.Structural Configuration and Buckling LengthsThe checking module uses output from the tower builder (in which thetower data is assembled from a list of panel types and dimensions) todetermine the nature of a member and its configuration related to therecommendations set out in the Commentary to the ASCE Manuals andReports on Engineering Practice No. 52 – “Guide for Design of SteelTransmission Towers” – Second Edition (1988), to determine bucklinglengths.


If the face has cross-bracing that is not braced against out-of planebuckling at the intersection point, the forces in both diagonals aredetermined so that the critical L/r ratios and allowable stresses may beassessed in accordance with Example 7 of the design guide.Effective Slenderness RatioEffective slenderness ratios KL/r are determined in accordance with therules of ASCE Manual 52 using member classification and continuityinformation generated during tower building. Unless otherwise specifiedin the tower data file, the checking module assumes that legs, braces, andhorizontals are connected with two or more bolts and that redundantsand plan and hip bracing are connected with single bolts.Calculation of Allowable StressesThe allowable stresses, including any appropriate wind overstressfactors, are calculated from the rules of Section 3. Flexural stresses arenot checked.BoltsBolts are checked for shear and bearing using the rules in Chapter J ofthe AISC “Specification for Structural Steel in Buildings – 1989”. Nochecks are made on edge distance or spacing requirements.ReportFor each panel in the tower, the report lists the member number, theclassification (leg, brace, etc.), the section size and yield strength, themost critical load case, the sub-clause of Manual 52 used in determiningthe effective slenderness ratio, the effective slenderness ratio andwhether it is about the x-x, y-y or v-v axes, the axial design force, thecapacity, and the ratio of design load to capacity.An expanded version of the report more suitable for detailed checking ofthe results for particular members is available. This report may be quitelarge.RestrictionsThis version of member checking to EIA-222-F has the followingrestrictions:• Members are checked for axial force only.• No check is made on “man-load” on horizontal or nearly horizontal

member.


Obtaining Design ResultsAfter checking members the results may be displayed or reported in anumber of ways:• Use the Results > Design Ratios command to display design results

with members color-coded to show the percentage of membercapacity actually utilized in the critical load case. With this display,all members that have failed a design check are shown in a shade ofred.

• Use the Query > Design Member command to show a summary ofdesign results in the Output window for any selected member.

• The design reports may be previewed with the File > Print Previewcommand and may be printed with the File > Print File command.Note that there are extensive facilities for formatting the designreport using the File > Page Setup command.

The report files are automatically deleted when the job is closed.The member check reports are created in the data folder and are named:Job.RPT – summary reportJob.RP2 – detailed report,where “Job” is the job name. You may save a steel design report file bydragging it to another folder using Windows Explorer.

Steel DetailingInformation may be exported in SDNF format for transfer to third-partysteel detailing programs (e.g. Xsteel). Refer to “Exporting a SteelDetailing Neutral File” on page 142.


Editing the Steel Section LibraryThe File > Configure > Edit Section Library command allows you toadd section properties and material properties to library files or togenerate new library files. Library files have the file name extension“LIB” (e.g. As.LIB, Uk.LIB) and cannot be listed, printed, or edited. Foreach library file, a corresponding source file contains the data fromwhich the library file is generated. Library source files are ordinary textfiles having a file name extension of “ASC” (e.g. As.ASC, Uk.ASC).

You may edit any librarysource file supplied but it ispreferable to make a copyand edit that – otherwise,you will lose your changeswhen you next updatelibrary files.

On selecting the above command, a dialog box is displayed for you tochoose one of the library source files. These are displayed with a prefix,“Prog:”, “Data:”, or “Libr:”, indicating the folder in which it is located.The MsEdit program then starts for you to edit the selected file. Whenyou close MsEdit a message box asks if you want to make the libraryfile. Answer Yes for MStower to create the new library file.

Data required for the section library is:ltype lverstitlenu u1 u2 u3 u4S dt name d1 ... dn f y1 y2......

where:ltype Library type, always 6.lvers Version, always 1.title Library description.nu Number of conversion factors, always 4.u1 Number of mm in units used to give the dimensions of the

section.u2 Number of mm in units used to give the derived properties of

the section. In UK libraries, dimensions are normally in mmwhile derived properties are in cm, sou1 = 1.0 andu2 = 10.0.

u3 Number of kg/m in units used to give the mass/unit length ofthe section.

u4 Number of N/mm2 (MPa) in units used to give the yieldstrengths of the section.

S Character “S”, in the first column of the line.dt Design type, tabulated below.name Section name, not more than 15 character, with no embedded

spaces.d1..dn Section data, consisting of section properties and dimensions.

Each design type requires a different set of data, as tabulatedbelow.


f Always 0.y1 Yield strength for normal grade steel.y2 Yield strength for high strength steel.

Note that the library type, title, and conversion factors must be on thefirst, second, and third lines, respectively of the file. They will normallybe present and will not require editing. You must ensure that any datayou enter is in units consistent with those of the rest of the library.

MsEdit has powerful“column editing” facilitieslike those in MicrosoftWord. Press the Alt key andyou can make a rectangularselection that includes oneor more columns.

The format of the library source file is specified for each design type inthe tables below. There are template records in the library source file tohelp you add new data correctly. The value of any section property inputas zero is computed automatically provided sufficient dimensions for thecalculation have been input. In these calculations, fillets and chamfersare neglected. For compound sections, dimensions are for a singlecomponent.

Design Type1 TFB Taper flange beam2 UB, WB Universal beam or welded beam3 UC, WC Universal column or welded column4 RHS Rectangular hollow section5 SHS Square hollow section6 CHS Circular hollow section7 PFC Parallel flange channel8 Tee Tee section9 EA Equal angle10 UA Unequal angle11 DAL Double angles, long legs together12 DAS Double angles, short legs together16 STA Starred angles22 QAN Quad angles13 UBP Universal bearing pile17 TFC Taper flange channel18 Rod Round19 Bar Rectangular bar20 CTT Double channels, toes together21 CBB Double channels, back-to-back24 CA DuraGal cold-formed angle25 CC DuraGal cold-formed channel30 *** Section with analysis properties only


The section mnemonic is embedded in the section name and, for alibrary section, is the only part of the name that may be alphabetic.Every section in a section category must have the same sectionmnemonic. During the design process you specify the kind of sectionsthat may be selected by entering one or more section mnemonics (seeabove). The section mnemonics that are entered are used to extractdesign candidate sections from the library.The available types of compound section are shown in the diagrambelow.

COMPOUND SECTIONS


Key to Section Library Parameters – Part 1 of 3DT Type 1 2 3 4 5 6 7 8 9 101 TFB A Ax Ay J Ix Iy Zx rx ry Zy

2 UB A Ax Ay J Ix Iy Zx rx ry Zy

3 UC A Ax Ay J Ix Iy Zx rx ry Zy

4 RHS A Ax Ay J Ix Iy Zx rx ry Zy

5 SHS A Ax Ay J Ix Iy Zx rx ry Zy

6 CHS A Ax J Ix rx Zx tw M D Sx

7 PFC A Ax Ay J Ix Iy Zx rx ry Zyt

8 T A Ax Ay J Ix Iy Zxs rx ry Zy

9 EA A Ax J Ix rx Zx t M D Sx

10 UA A Ax Ay J Ix Iy Zx rx ry Zy

11 DAL A Ax Ay J Ix Iy Zx rx ry Zy

12 DAS A Ax Ay J Ix Iy Zx rx ry Zy

13 UBP A Ax Ay J Ix Iy Zx rx ry Zy

14 CB A Ax Ay J Ix Iy Zx rx ry Zy

15 CC A Ax Ay J Ix Iy Zx rx ry Zy

16 STA A Ax Ay J Ix Iy Zx rx ry Zy

17 TFC A Ax Ay J Ix Iy Zx rx ry Zyt

18 ROD A Ax J Ix M D f y1 y2

19 BAR A Ax Ay J Ix Iy M D B f

20 CTT A Ax Ay J Ix Iy Zx rx ry Zy

21 CBB A Ax Ay J Ix Iy Zx rx ry Zy

22 QAN A Ax Ay J Ix Iy Zx rx ry Zy

30 *** A Ax Ay J Ix Iy

DT Type 1 2 3 4 5 6 7 8 9 10

Key to Section Library Parameters – Part 2 of 3DT Type 11 12 13 14 15 16 17 18 19 201 TFB M D B tf tw RR DF Sx Sy Iw

2 UB M D B tf tw RR DF Sx Sy Iw

3 UC M D B tf tw RR DF Sx Sy Iw

4 RHS M D B tw Sx Sy f y1

5 SHS M D B tw Sx Sy f y1

6 CHS f y1 y2

7 PFC M D B tf tw RR DF Sx Sy Iw

8 T M D B tf tw RR DF Sx Sy Iw

9 EA cy ex Iu Zu1 ru Iv Zv1 rv tan f

10 UA M D B t Sx Sy cx cy ex ey

11 DAL Sx Sy M D B t g sp rv f

12 DAS Sx Sy M D B t g sp rv f

13 UBP M D B tf tw RR DF Sx Sy Iw

14 CB M D B tf tw RR DF Sx Sy Iw

15 CC M D B tf tw RR DF Sx Sy Iw

16 STA Sx Sy M D B t g sp rv f

17 TFC M D B tf tw RR DF Sx Sy Iw

18 ROD

19 BAR y1 y2

20 CTT Sx Sy M D B tf tw g sp ry

21 CBB Sx Sy M D B tf tw g sp ry

22 QAN Sx Sy M D B t g sp rv f

30 ***

DT Type 11 12 13 14 15 16 17 18 19 20


Key to Section Library Parameters – Part 3 of 3DT Type 21 22 23 24 25 26 27 28 29 301 TFB f y1 y2

2 UB f y1 y2

3 UC f y1 y2

4 RHS

5 SHS

6 CHS

7 PFC cy Zyw ey f y1 y2

8 T cx Zxf f y1 y2

9 EA y1 y2

10 UA Iu Zu1 ru Iv Zv2 rv tan f y1 y2

11 DAL y1 y2

12 DAS y1 y2

13 UBP f y1 y2

14 CB f y1 y2

15 CC f y1 y2

16 STA y1 y2

17 TFC cy Zyw ey f y1 y2

18 ROD

19 BAR

20 CTT f y1 y2

21 CBB f y1 y2

22 QAN y1 y2

30 ***

DT Type 21 22 23 24 25 26 27 28 29 30

Legend – I SectionA = Gross areaAx = Shear areaAy = Shear areaJ = Torsion constantIx = Second moment of areaIy = Second moment of arearx = Radius of gyrationry = Radius of gyrationZx = Elastic modulusZy = Elastic modulusM = Mass per unit lengthD = DepthB = Breadthtf = Flange thicknesstw = Web thicknessRR = Root radiusDF = Depth between filletsSx = Plastic modulusSy = Plastic modulusIw = Warping constantf = Residual stress codey1 = Yield normal strength steely2 = Yield high strength steel


Legend – Channelcy = Distance to center of areaey = Distance to shear centerZyt = Elastic modulus – toeZyw = Elastic modulus – web

Legend – Teecx = Distance to center of areaZxs = Elastic modulus – stemZxf = Elastic modulus – flange

Legend – AngleD = Length of long legB = Length of short legt = Thicknesscx = Distance to center of areacy = Distance to center of areaex = Distance to shear center ey = Distance to shear centerIu = Second moment of area – majorIv = Second moment of area – minorru = Radius of gyrationrv = Radius of gyrationZu1 = Elastic modulus – toeZv1 = Elastic modulus – heelZv2 = Elastic modulus – toetan = Tangent of angle to principal axes

Legend – Compound Sectionsg = Gap between component sectionssp = Stitch bolt or packer spacing

Editing Ancillary & Guy LibrariesThe File > Configure > Ancillary/Guy Library command allows youto add additional ancillaries or guys to these libraries. There are templaterecords in each library to help you add new data correctly.On selecting the above command, a dialog box is displayed for you tochoose one of the library source files. These are displayed with a prefix,“Prog:”, “Data:”, or “Libr:”, indicating the folder in which it is located.The MsEdit program then starts for you to edit the selected file. The data required in each of these library types is set out in “GuyLibrary” on page 52 and “Ancillary Libraries” on page 136.

MSTower V5 13:Examples • 181

13:Examples

Use the following procedure to run an MStower job:1. Start MStower (see “Starting MStower” on page 7).2. Select the File > Open command and in the dialog box browse to

the Examples folder (see “Folders” on page 6). Choose one of theexample jobs, say TWEX1 or TWEX10-US, and then click theOpen button. The tower should now be displayed – if not, select theTower > Build Tower > Process Tower Data File command

3. Select the Tower > Build/Load/Analyse command.4. Close the analysis window when it displays “Linear analysis

completed”.5. If checking to BS 8100 select the Tower > Gust Factor command.6. Select the appropriate design code on the Member Check menu. If

checking to BS 8100, select only the first load case of each set ofcombinations as the results of the gust factoring and square root ofthe sum of the squares is written to this case.

7. Select the Results > Design Ratios command and the structure willbe displayed with overstressed members colored red.

8. To display the results of the member checking select the File >List/Edit command and then click either the Summary or Detailedbutton. The selected report file will now be displayed in the MsEdittext editor. You may use the File > Print Preview command to seeeach page of the report, exactly how it will appear when printed.

To run a mast job, proceed as set out above but when the Analysis LoadCases dialog box appears select Case 100 and all combination loadcases. When the Non Linear Analysis Parameters dialog box is displayedclick OK to accept the default values. The non linear analysis requiredfor masts takes longer than linear analysis.To run an existing MStower Version 4 job select the File > Newcommand, confirm the job file folder, enter the job name and thenproceed from Step 3, above.

Note: When requesting support by telephone, please be ready at yourcomputer in order to assist support staff in finding your problem.

182 • 13:Examples MSTower V5


When MStower is installed a number of job files are located in theExamples folder (see “Folders” on page 6). These jobs are describedbelow. Plots are shown on the previous page. Analysis of masts requiresthe catenary cable option and non-linear analysis.Example Towers (metric units)TWEX1 – A plain tower to illustrate member checking to BS 8100. AnAutoCAD drawing file, Twex1.DWG may be found in the Examplesfolder and may be plotted as a reference.TWEX2 – A communications tower composed of standard panels with anumber of linear, large, and face ancillaries. For checking to BS 8100.TWEX3 – As TWEX2. For checking to CP3 / BS 449.TWEX4 – A power line tower using UDPs with asymmetrical cross-arms. For checking to BS 8100.TWEX5 – A communications tower to the American Standard usingmetric units. For checking to EIA-222-F.TWEX6 – An example to illustrate the checking of ancillary deflectionsand rotations to BS 8100.Example Masts (metric units)TWEX7 – A 500 ft. guyed mast to illustrate member checking toBS 8100:Part 3. Includes a database file.TWEX8-SM – As TWEX7, incorporating smeared wind loading on guysaccording to Eurocode proposals.TWEX9 – As TWEX7, with ice loading.Example Towers (American units)TWEX10-US – A plain tower to illustrate member checking to EIA222-F. An AutoCAD drawing file, Twex10.DWG may be found in theExamples folder and may be plotted as a reference.TWEX11-US – A communications tower composed of standard panelswith a number of linear, large, and face ancillaries. For checking toEIA222-F.TWEX12-US – The Todthill communications tower, Staten Island, NewYork. Uses pipe sections. For checking to EIA222-F.Example Mast (American units)TWEX13-US – The Echo-PA mast in Washington. Uses an anti-twistframe. For checking to EIA222-F.

Note: Examples TWEX7, TWEX8-SM, TWEX9, and TWEX13-US arecomputationally intensive, using iterative analysis. You should onlyattempt these examples on a reasonably powerful computer, e.g. 500MHz Pentium III with 128 MB RAM.


TWEX1 & TWEX10-USThese examples are for a plain tower, TWEX1 for checking to BS 8100and TWEX10-US for checking to EIA222-F. AutoCAD drawing files,Twex1.DWG and Twex10-US.DWG may be found in the Examplesfolder and may be plotted as a reference.

TWEX1& TWEX10-US


TD File – TWEX1TITL1 TWEX1- Tutorial- see Acad dwg TWEX1.DWGTITL2UNITS 1 $ Metric units ---------------------------

PROFILEFACES 4WBASE 2.000RLBAS 0.0000

$ Section 1 ------------------------------------------

PANEL 1 HT 1.000 TW 1.500FACE DR LEG 1 BR1 5 H1 4BOLT BR 1 M16-8 H 1 M16-8

PANEL 2 HT 1.000FACE DL0 LEG 1 BR1 5

PANEL 3 HT 1.000FACE DR LEG 1 BR1 6 H1 6PLAN PL1A PB1 0 PB2 4 PB3 0BOLT LEG 4 M16-8 BR 1 M16-8 H 1 M16-8 PB 1 M16-8

$ Section 2 ------------------------------------------

PANEL 4 HT 1.000FACE DL LEG 2 BR1 6 H1 8BOLT LEG 0

PANEL 5 HT 1.000FACE DR LEG 2 BR1 6 H1 8PLAN PL1A PB1 0 PB2 4 PB3 0

PANEL 6 HT 1.000FACE DL LEG 2 BR1 6 H1 0

PANEL 7 HT 1.000FACE DR LEG 2 BR1 6 H1 0

PANEL 8 HT 1.000FACE DL LEG 3 BR1 7 H1 0BOLT LEG 4 M16-8

$ Section 3 ------------------------------------------

PANEL 9 HT 1.500FACE K LEG 3 BR1 5 H1 8BOLT LEG 0

PANEL 10 HT 1.500FACE K LEG 3 BR1 5 H1 8PLAN PL1A PB1 0 PB2 4 PB3 0

PANEL 11 HT 2.000FACE K LEG 3 BR1 7 H1 8BOLT LEG 4 M20-82 $ Bolts in double shear

END

SECTIONS

LIBR P:UK IFACT 1.0 $ Use UK if library is in the Data Area

$ LEGS $ Bolts are 16 Dia in 17.5 Dia holes

1 EA80X80X8 Y FY H BH 35 $ Concentric connections of members is the default2 EA100X100X10 Y FY H BH 353 EA120X120X12 Y FY H BH 35

$ BRACING

4 EA50X50X6 Y FY N BH 17.5 CONNECT L5 EA60X60X8 Y FY N BH 17.5 CONNECT L6 EA50X50X5 Y FY N BH 17.5 CONNECT L7 EA60X60X10 Y FY N BH 17.5 CONNECT L8 EA60X60X6 Y FY N BH 17.5 CONNECT L

END

BOLTDATA

M24-82 GR8.8 D 24 AS 452 FY 628 FU 785 NSP 2 $ BS3692 grade 8.8M22-82 GR8.8 D 22 AS 380 FY 628 FU 785 NSP 2 $ 2 SHEAR PLANESM20-82 GR8.8 D 20 AS 314 FY 628 FU 785 NSP 2

M24-8 GR8.8 D 24 AS 452 FY 628 FU 785 $ BS3692 grade 8.8M22-8 GR8.8 D 22 AS 380 FY 628 FU 785M20-8 GR8.8 D 20 AS 314 FY 628 FU 785M16-8 GR8.8 D 16 AS 201 FY 628 FU 785

END

END


TWR File – TWEX1$ from FILE TWRSTD.TWR$ prototype TWR file for square tower.

$ STATION$ HEIGHT$ NGR SP$ MAP No

$ STRUCTURE

$ TYPE:-$ MANUFACTURERS:-$ ANCILLARIES Drg$ Amendments$$ CAD REF$ STRUCTURAL DRAWINGS :-$

PARAMETERSANGN 45.0CODE BS8100 $ WIND PROFILE TO THIS CODEICE RO 0.0 RW 0.0 $ALTOP 0 $ SITE + TOWER HEIGHTPSF-V 1.20 $PSF-M 1.20 $VB 30.0 MEAN $ ENTER SITE WINDSPEED HERE MEAN HOURLY FOR BS8100OVERLAP 1

END

TERRAINANGLE 0 TCAT 2 $ HH 0.0 BETAH 0.0 XLEE 0.0

END

LOADSCASE 100 Weight of tower plus ancillaries

DL$ TODO - any additional NDLDs go here

CASE 200 wind at 180 to X axisWL ANGLX 180.0 NOICE



CASE 500 Max. tower weightCOMBIN 100 1.050

CASE 520 TENSION: wind at 180 to X axisCOMBIN 100 0.900COMBIN 200 1.000

CASE 540 COMPRES: wind at 180 to X axisCOMBIN 100 1.050COMBIN 200 1.000





END

ANCILLARIES

$ DUMMY ENTRIES FOR GUIDANCE ONLY

LARGE LIBR P:ANC.LIB $ use ANC.LIB if library is in DATA area

DISH-1 XA 1.0 YA 1.0 ZA 11 LIB SH1PR-6 ANG 0

LINEAR LIBR P:LIN.LIB $ use LIN.LIB if library in DATA area


fdrs XB .5 YB .5 ZB 0 XT .5 YT .5 ZT 11 LIB FDRS-SMALL

$ FDRSds XB 00.0 YB 00.0 ZB 00.0 XT 00.0 YT 00.0 ZT 00.0 LIB FDRS-SMALL

FACE

$ SCREEN6 FACE 1234 ZA 00.0 MASS 00 CN 0.0 AREA 0.0 FLAT

ENDEND

The member check summary report for TWEX1 is shown in thefollowing pages. The detailed report for this example is almost 100pages in length.






MSTower V5 14:Ancillary Programs • 193

14:Ancillary Programs

CTIDATACTIDATA generates a tower data (TD) file from a prototype TWR fileand Cti.CSV database file.To run CTIDATA from the main menu select the Tower > Load Tower> Process Ancillary DB File command.This command will not be available unless a tower geometry has beenbuilt and the CSV file exists in the data folder.The prototype TWR file, Ctistd.TWR must be present in the data folderand the geometry of the structure must have been created.A tower loading file is output.When CTIDATA is run a number of dialog boxes are presented for youto choose codes and enter parameters that will be substituted into a copyof the prototype TWR file.A set of wind angle and load combinations is entered for generation of anew LOADS block. All wind load directions are referred to the tower Xaxis, simplifying the generation of face and corner winds. Any or all faceor corner wind directions may be chosen. In addition, for triangulartowers, winds parallel to faces may also be chosen.Any large ancillary data in the prototype file is replaced with dataderived from the CSV file.If the tower loading file exists before CTIDATA is run, only the largeancillary data will be replaced. The PARAMETERS and LOADS blockswill be unchanged and previously existing ancillary loads will becommented out and remain in the file for possible future reference.Arrangements may be made to customize this program to userrequirements.

194 • 14:Ancillary Programs MSTower V5

MSTower V5 Glossary • 195

Glossary

CableA structural member capable of resisting axial tension only in itsundisplaced position.

CaretA small vertical flashing line that marks the text insertion point.

ClickTo depress and release the left mouse button.

Context menuThe menu that appears when you click the right mouse button.

CQCComplete Quadratic Combination. A general method for thecombination of the responses of individual vibration modes.

CursorThe marker on the screen that corresponds to the position of the mouse.

Data tipA small information window, similar to a tooltip, that appears when thecursor passes over a node or a member.

DOFDegree of freedom – a unit for measuring the different ways in which astructure can displace under the action of applied loads. At each DOFthere may be an applied force and a displacement will be computed.

DXFDrawing eXchange File. A file format used to import data into or exportdata from a CAD program.

196 • Glossary MSTower V5

ECLElastic Critical Load – a buckling load.

EMFEnhanced Metafile Format – a vector picture format.

Global axesThe set of rectangular axes in which node coordinates are measured.Usually referred to as X, Y, Z.

LambdaFrame buckling load factor, λc.

Local axesSee Member axes.

MechanismAn assemblage of structural members having one or more modes ofdisplacement that can occur without distortion of any member.

Member axesThe set of rectangular axes attached to each member at the “A” end.Usually referred to as x, y, z. x is the longitudinal axis of the member andy and z are transverse axes coinciding with the principal axes of themember cross-section.

Right-clickTo depress and release the right mouse button. This action invariablyinitiates the display of a context menu.

SRSSSquare Root of Sum of Squares.

TooltipA small information window that may appear when the cursor passesover a toolbar button or a dialog box item.

MsTower V5 Index • 197

Index

AAccelerator keys 105Additional Member Temperatures

125Additional Node Loads 124Analyse menu 20Analysis

Buckling 152Elastic critical load 152Non-linear 145Second-order 145

Ancillary Block 126Attributes toolbar 27AutoCAD 141

BBlocks

Ancillary 126Bolt Data 50Component 37Guy List 120Guys 45Loads 121Material 49Named Node 120Panel 126Parameters 114Profile 38Sections 46Supports 44Terrain 116Title 37Velocity Profile 118

Bolt Data Block 50Boundary 111Break line 101Buckling 152

CCable 148Colors 10Combination Load Cases 125Component Block 37Compound angle sections 48Compound sections 173Configuration 10Context menu 8, 100, 106Coordinates 100Cross-arms 59, 88Crossing window 105Ctrl+A 105, 106Ctrl+C 105Ctrl+V 105Ctrl+X 105Ctrl+Y 105Ctrl+Z 105Cursor 104Customize 30Cylindrical coordinates 101

DD & V face panels 60Data tip 15Dead Loads 123Default printer 12Delete 105Detailing 142, 170Directories 6Display toolbar 26DLM & DRM face panels 79DM face panel 77DMH face panel 78Double-click 9, 106Draw toolbar 27Drawing 100Drawing plane 103Duplicate members 103Duplicate nodes 103

EECL 152Edit

Section library 13Effective length 152Elastic critical load analysis 152E-mail 14EMF 142End line 102Examples 7Explorer 9

198 • Index MsTower V5

ExportDXF 141

Extra Buttons toolbar 29

FF5 105Face Ancillaries 130Face Panels 54

D & V 60DLM & DRM 79DM 77DMH 78K 65KXM 80M 73W 75X 61XDMA 81XMA 76

File menu 16File type 9Fixed-end actions 147Folders 6Frame buckling 151

GGuy List Block 120Guyed Mast Patch Loadings 123Guys Block 45

HHardware lock 5Help About dialog box 14Help menu 24Help toolbar 26Hip bracing 59, 86Home 105Hot-links 14

IIce Loads 124Input load case 15Instability 151Installation 5Insulators 132Internet 14Interruptible commands 104

JJob size 10

KK face panels 65KXM face panel 80

LLambda 152Large Ancillaries 131Launch 9Limit 110Linear Ancillaries 128Loads

Additional Member Temperatures125

Additional Node 124Dead 123Guyed Mast Patch 123Ice 124Miscellaneous 124Wind 122

Loads Block 121

MM face panels 73Main toolbar 24Main window 15Material Block 49Member Checking menu 18Member properties 107Members

Non-Linear 148Menu bar 15Menus 15Miscellaneous Loads 124MStower Web Site 14Multiple selection 108

NNamed Node Block 120Node properties 107Non-linear analysis 145

OOK/Cancel toolbar 28Output window 15, 30

MsTower V5 Index • 199

PPage Setup 12Panel Block 126Parameters Block 114P-delta effect 146, 147P-Delta effect 146, 147Plan bracing 58, 82Pop-up menu 8, 106Printing in MStower 11Profile Block 38Prompt 15

QQuery menu 22

RRectangular coordinates 101Relative coordinates 101Report files 170Reports menu 21Results menu 20Results toolbar 28Right-click 100, 106

SSecond-order analysis 145Section axis 47Section library 13Sections Block 46Select members 105Select nodes 105Selection box 105Serial number 14Shortcut 9Shortcut keys 105Show menu 21Snap mode 15, 102

Grid 102Intersection 102Mid/End 102Nearest 102Orthogonal 102Perpendicular 102

Space 105Spherical coordinates 101Status bar 15Steel detailing 142, 170Stretch 109Structure menu 19Subset 110Support 14

Supports Block 44

TTechnical support 14Tension-only 148Terrain Block 116Text editor 31Text file 31, 171Title Block 37Toolbars 15, 29

Cool look 29Flat style 29Large buttons 29Reset 29

Tower menu 18Troubleshooting 151

VVelocity Profile Block 118View menu 17View toolbar 25

WW face panels 75Wind Load Cases 122Window 110Window menu 23

XX face panels 61XDMA face panel 81XMA face panel 76Xsteel 170

200 • Index MsTower V5

Documents

MST5