Composite Column Enu

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ManualComposite column design


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Composite column design

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All information in this document is subject to modification without prior notice. No part or this manualmay be reproduced, stored in a database or retrieval system or published, in any form or in any way,electronically, mechanically, by print, photo print, microfilm or any other means without prior writtenpermission from the publisher. Scia is not responsible for any direct or indirect damage because ofimperfections in the documentation and/or the software.

Copyright 2008 Scia Group nv. All rights reserved.


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Table of contentsIntroduct ion .............................................................................................................................................. 1Typical operations ................................................................................................................................... 2

Defining the pro ject funct ionality .................................................................................................... 2Defining the composite column ....................................................................................................... 3

Defining the structural steel section ............................................................................................... 4Defining the concrete ..................................................................................................................... 4

Completing the model....................................................................................................................... 5Defining the load cases and corresponding loads ........................................................................ 6Running the analysis calculations .................................................................................................. 6Defining the reinforcement .............................................................................................................. 7

Defining the stirrup ......................................................................................................................... 7Defining the longitudinal steel ...................................................................................................... 10

Defining the parameters fo r code check in Composite->Setup................................................. 10Defining the parameters in Composite->Member data ............................................................... 13Defining the member buckl ing data .............................................................................................. 14Performing the code check for ULS or f ire lim it state ................................................................. 14

Result s: Composite column code check ............................................................................................ 16ULS check ........................................................................................................................................ 16Fire resistance checks .................................................................................................................... 19


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Introduction

This document describes the composite column functionality within SCIA Engineer. Thedesign checks that can be performed on the composite column and their results arepresented in detail.This document may be read in conjunction with the theoretical background document to

get a better insight into the working of this module.


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Typical operations

Typical operating sequence in the design check of composite columns would involve thefollowing:

Defining the project functionality

Defining the composite column using 1D Member->Column or Catalogueblocks.

Completing the model

Defining the load cases and the corresponding loads

Running the analysis calculations

Defining the reinforcement

Defining the parameters for code check in Composite ->Set up

Defining the parameters for code check in Composite->Member data (ifrequired).

Defining the member buckling data

Performing the code check for ULS or Fire limit statesThe above sequence is now illustrated in detail through the sections below.

Defining the project functionality

First and foremost a project is defined with concrete and steel and composite optionchecked in the functionality. The user has an option to include or not, the compositebeams in the structural model based on its requirement. The consequence of selectingthe composite beam in the structural model is explained in section .If it is expected to carry out checks pertaining to fire limit state besides ULS design

checks; fire resistance is also checked in the functionality.Since, the composite column check is supported for the Euro Code 4 only; the Nationalcode is selected as EC-EN.


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Figure 1: Defining the project data

Defining the composite column

The composite column may be defined through 1D-Member->Columnor CatalogueBlocks. The composite column cross section is defined by selecting any of thecomposite sections in the groups Composedin the New cross-sections dialog box.


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Figure 2: Selecting the requisite composi te section.

Defining the structural steel section

A rolled or welded structural steel section may be selected corresponding to compositesections types a ;b ; d ; e. For composite section type c only a rolled section is tobe selected.Defining the structural steel section includes defining the grade; dimensions (in case ofwelded) else selecting a suitable type from the profile library in case of rolled.

Defining the concrete

Concrete dimensions need be defined only in case of composite sections of type fullyconcrete encased with I sections. This is done by defining the covers ta and tb tostructural steel.It may be noted that the covers ta and tb to structural steel as illustrated in the figurebelow are equal on either side to achieve a symmetrical section.


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Figure 3: Defining the struc tural steel and concrete in a composite section

Completing the model

The model is completed by placing the composite column of suitable length on the

screen (if defined through 1D Member->Column)orplacing the catalogue block (afterdefining the number of bays and the length of each bay) on the screen. The supportsare defined in a usual fashion throughModel data->Support in node.A rendered geometry of the model may be viewed if required.

Figure 4: Rendered geometry


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Defining the load cases and corresponding loads

As mentioned in section 2.1 if composite beam is a part of the project; then the userwould need to define a construction stage load case through the solver set-up.

Figure 5: Defining the cons truction stage load case(only if composite beam is included inthe project)

However; design checks for composite column are not distinguished as constructionstage checks or final stage checks (as in composite beams); that is to say that designchecks for composite column are always carried out using composite section properties.

Running the analysis calculations

The analysis calculations are now carried out. It may be noted that the analysis could be

carried for a linear combination or for a non-linear combination.


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Defining the reinforcement

Defining the reinforcement includes:

Defining the ties (stirrups)

Defining the longitudinal steel

This can be done through:Composite->Redes->New stirrup reinforcementfollowed byComposite->Redes->New longitudinal reinforcementElse, the same could be defined using Composite->Redes->New reinforcement

Figure 6: Defining the reinforcement using REDES

In either case the definition of longitudinal steel is to be preceded by the definition ofstirrups.Based on the shape of the composite section the corresponding suitable shape of thestirrup will be provided.

Defining the stirrup

The stirrup may be defined using the option New stirruporAutomaticin the stirrupshape dialog box.


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Figure 7: Defining the stirrup

Defining the stirrup using the option New stirrupwould require defining the end nodes of

each stirrup bend specifying the relative/absolute position.

Defining the stirrup using the optionAutomatic would result in a default shape beingprovided as shown in the figure below.


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Figure 8: Defining the sti rrup using theAutomatic option

Figure 9: Defining the stirrup us ing New Stirrupoption


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Defining the longitudinal steel

Defining the longitudinal steel requires selecting the edge and then defining the

reinforcement parameters corresponding to that edge. Having defined the parametersclicking on the New layeroption would insert the reinforcement bars based on thedefined parameters. If the layers defined for a section do not result in a symmetricaldistribution of reinforcement in the section then a message is prompted to the userregarding the same and the defined reinforcement will not be accepted.

Figure 10: Defining the longitudinal steel

Defining the parameters for code check in Composite->Setup

Only the parameters which are relevant to composite column design are discussedbelow:

Material PSF (partial safety factors)

These include the partial safety factors for structural steel, reinforcing steel, concreteand headed studs (shear connectors). PSF corresponding to structural steel work(buckling resistance) is used for axial compression check.

PSF corresponding to profile steel sheet is not part of composite column design check.


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Calculation parameters

These include proportion of total load that is long term(used in computing the flexuralstiffness of the composite column considering the time dependent effects); shearconnector data and data pertaining to structural steel.

Buckling defaults

Those used as part of the composite column design check include; default sway types,buckling length ratios ky and kz, maximum k ratio


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Figure 11: Defining the parameters in Composi te->Set up

Defining the parameters in Composite->Member data

Data pertaining to shear connector defined as part of the set up data can be overriddenby that in the Composite->Member datafor a specific member(s)

The buckling length ratios for fire limit state can be defined differently than that forultimate limit state.

A user defined temperature time curve may be used for a specific member(s) instead ofstandard temperature time curve for composite column design checks


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Figure 12: Defining parameters in Composi te>Column Member data

Defining the member buckl ing data

The parameters pertaining to the member buckling data may be defined / redefined inthe dialog box corresponding to Composite->1D member->Member buckling data

Figure 13: Defining parameters in Composite->Member buckling data

Performing the code check for ULS or fire limit state

Following the steps above the user may perform the code check for ULS or/and fire limitstate.The results for each of the limit states are discussed in the next section


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Figure 14: Design checks


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Results: Composite column code check

The results corresponding to ULS check and fire check are presented in this section.

ULS check

ULS design check is comprised of:

Check 1: Pure axial

Check 2: Combined axial plus uniaxial bending

Check 3: Combined axial plus biaxial bending

Check 4: Longitudinal shear check

Check 5: Transverse shear checkThe checks are carried out about both the principal axis. The design philosophyinvolving the above checks as well as the corresponding clause reference is discussedin detail in the theoretical background document.

The results can be viewed in the following output formats:1. Detailed output

2. Normal output

3. Brief outputDetailed output

In case of detailed output the parameters/variables involved in each of the abovechecks are presented.


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Figure 15: Detailed output

Normal output

In case of normal output only the effect (internal force), resistance and theutilization

ratio pertaining to the checks 1 through 4 is displayed.

Figure 16: Normal output

Brief output:

In case of detailed output, the most critical utilization ratio of all the above checks at asection is displayed


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Figure 17: Brief output

Fire resistance checks

Fire resistance check is not supported for composite sections of type concrete filledcircular hollow sections incorporating an I section and partially concrete encased withcrossed I sections due to non-availability of data pertaining to temperature distributionfor these sections.Fire resistance check is comprised of pure axial check in accordance to the relevantcode. In depth details can be found in the theoretical background document.The results pertaining to the composite sections are presented below:

Fully concrete encased sections:Check in accordance to the Tabulated data in Table4.4

Partially concrete encased sections:Balanced summation model as described inAnnex G.


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Concrete filled circular hollow sections and concrete filled rectangular (or square)hollow sections:Generalized design method as described in clause4.3.5.1 as well asthe alternative design method described in the Annex-H

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Composite Column Enu