EC3 Design (Staad Manual)

8/19/2019 EC3 Design (Staad Manual)

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STAAD.Pro is capable of performing steel design based on the European code EC3 BS EN 1993-1-1:2005Eurocode 3: Design of steel structures Part 1.1 General rules and rules for buildings.

The implementation of EN1993-1-1:2005 includes the amendments as per CEN corrigenda ofFebruary 2006 and April 2009.

Design of members per EC3 BS EN 1993-1-1:2005 requires the STAAD ECC Super Code SELECT CodePack or the STAAD UK Super Code SELECT Code Pack.

7C.1 General Description

7C.2 Analysis Methodology

7C.3 Material Properties and Load Factors

7C.4 Section Classification

7C.5 Member Design

7C.6 Design Parameters

7C.7 Code Checking

7C.8 Member Selection

7C.9 Tabulated Results of Steel Design

Page 1 of 1EC3 -EN 1993_TOC

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EN 1993-1-1:2005 does not specifically deal with single angle, double angles, double channelsor Tee sections and does give a method to evaluate the slenderness of such members. In thesecases, the Eurocode 3 (EN 1993-1-1) design module of STAAD.Pro uses the methods specifiedin BS 5950-1:2000 to calculate the slenderness of these members. Cl. 4.7.10 of BS 5950-1:2000 isused in the current version of the EC3 design module. See "Single Angel Sections" for STand RA angle specifications.

Laced or battened compression members are not dealt within the current version of EC3 (EN1993) design module in STAAD.Pro.

Page 2 of 25B.5(B).3 Design of members with combined axial load and bending



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European Codes - Steel Design to Eurocode

7C.5.3 Members Subject to Shear

The cross section capacity of a member subject to shear is checked as per Cl. 6.2.6 of the code. Thecondition to be satisfied is:

Where:

V c,Rd is the is the shear design resistance given by:

A v is the shear area and is worked out for the various section types as given in Cl. 6.2.6(3) of the code.

Shear Buckling

For sections that are susceptible to shear buckling, the program will perform the shear bucklingchecks as given in Section 5 of EN 1993-1-5. The shear buckling checks will be done only for I –Sectionsand Channel sections. Shear stresses induced from torsional loads are taken into account whileperforming torsion checks.

Web shear buckling is checked in STAAD.Pro V8i (SELECTseries 3) (release 20.07.08) andlater.

The susceptibility of a section to shear buckling will be based on the criteria given in Cl 5.1(2) of EN1993-1-5 as is as given as follows:

a. For unstiffened webs, if hw /t > 72ε / η, the section must be checked for shear buckling.

The design resistance is calculated as:

Where:

h w = distance between flanges of an I Section (i.e., depth - 2x flange thickness).

t = thickness of the web

ε = √(235/f y ), where fy is the yield stress

η = 1.2 for steel grades up to and including S 460 and = 1.0 for other steel grades

kτ as defined in sections below

Page 1 of 35B.5(B).3 Members Subject to Shear



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χ w is the web contribution factor obtained from Table 5.1 of the EC3 code and is

evaluated per the following table:

Table 7C.1-Evaluate of χ w

Slenderness

Parameter

Rigid End

Post

Non-rigid End

Post

λw < 0.83/

η η η

0.83/ η ≤ λw < 1.08 0.83/ λw 0.83/ λw

λw > 1.08 1.37/(0.7 + λw ) 0.83/ λw

b. For stiffened webs, if hw /t > 31·E √k τ / η, the section must be checked for shear buckling.

The design resistances considers tension field action of the web and flanges acting as struts in atruss model. This is calculated as:

Where:

V bf,Rd is the flange resistance per Cl.5.4 for a flange not completely utilized bybending moment.

bf is the width of the flange which provides the least axial resistance, not to betaken greater than 15εt f on each side of the web.

tf is the thickness of the flange which provides the least axial resistance.

M f,Rd = M f,k / γ M0, the moment of resistance of the cross section consisting of theeffective area of the flanges only. For a typical I Section or PFD, this is evaluatedas b·t f ·hw. When an axial load, NEd, is present, the value of Mf,Rd is reduced by

multiplying by the following factor:

A f1 and A f2 are the areas of the top and bottom flanges, respectively.

a = transverse stiffener spacing. The equation of c is likewise used to solve for asufficient stiffener spacing in the case of demand from loads exceeding thecalculated capacity for a specified stiffener spacing.

The following equation must be satisfied for the web shear buckling check to pass:




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Where:

V Ed is the design shear force.

The shear forces due to any applied torsion will not be accounted for if the TOR parameter hasbeen specifically set to a value of 0 (i.e., ignore torsion option).

If the stiffener spacing has not been provided (using the STIFF parameter), then the program assumesthat the member end forms a non-rigid post (case c) and proceeds to evaluate the minimum stiffenerspacing required.




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European Codes - Steel Design to Eurocode 3

Detailed stress check

This method is used when the TORSION parameter is specified as two (2).

This method performs a detailed torsional analysis of a member depending on the torsion loadingconditions and the support conditions at the member ends. This method is based on the SCIpublication P057 and includes any warping stresses (direct warping stresses and warping shearstresses) depending on the end conditions of the member. This implementation considers sevendifferent cases of loading and end conditions as given in publication P057 – Section 6. Theloading/end conditions for a member are specified by the use of the CMT design parameter (See"Design Parameters" for parameter values and descriptions).

All the equations used to evaluate the torsional moments and associated stresses are as given in Appendix B of P057. The resultant stresses are evaluated at various sections along the length of the

member and the following checks will be performed:

Clause 6.2.7(1) – Torsional resistance of the section.

In general, the torsion at any section TEd is resolved into two components, viz.

The pure torsional (St. Venant’s) moment (Tt,Ed) and

The warping torsional moment(T w,Ed)

Therefore,

T Ed = T t,Ed + T w,Ed = GJ φ’ = EH φ’’’

[Ref SCI pub. P057]

Where:

φ’ and φ’’’ are the first and third derivates of twist (φ ), respectively, and depend on theend conditions and loading. These are evaluated from the equations in Annex B of P057and are based the specified CMT parameter.

Although the equation given the NCCI document SN007b-EN-EU can be used to evaluateT wrd, the NCCI does not give the eqn. to evaluate φ’’’. Therefore, Annex B of P057 is used.

The torsional resistance of the section is also considered as the sum of the pure torsion resistance andthe warping torsion resistance. The pure torsion resistance (Tt,Rd) and the warping torsional resistance

(T w,Rd) are evaluated as:

For closed sections:

T t,Rd = 2 · Ac · t · τ max

Where:

A c is the area enclosed by the mean perimeter

t is the max thickness

τmax is the max. allowable shear stress = (fy/√3)/ Γm0

Page 1 of 5European Codes - Steel Design to Eurocode 3 [EN 1993-1-1:2005]



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For open sections (I & channel):

T t,Rd = τ max · J / t

Where:

J is the torsion const

t is the max thickness.

T w,Rd = (f y / Γ m0 )· t · b2 / 6

Where:

b is the width of the section

t is the thickness of the flange for I- sections; minimum of flange or web thicknesschannel sections

The check according to Cl 6.2.7(1) will then be performed to ensure that the following conditions aresatisfied:

T t,Ed / T t,Rd ≤ 1

T w,Ed / T w,Rd ≤ 1

T Ed / T Rd ≤ 1

Clause 6.2.7(9) – Plastic shear resistance due to torsion

STAAD.Pro checks for shear resistance of a section based on Cl. 6.2.6 for EC3 and the plastic shearresistance (in the absence of torsion) is evaluated as:

Where:

A v is as pre Cl.6.2.6 (3) for the various sections

When torsion is present, along with the shear force, the design shear resistance will be reduced to V pl,T,Rd, where V pl,T,Rd is evaluated as follows:

i. For I or H Sections:

ii. For Channel Sections:

iii. For Structural Hollow Sections:

Where




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τt,Ed is the shear stress due to direct (St. Venant’s) torsion and

τ w,Ed is the shear stress due to warping torsion.

The various shear stresses due to torsion τt,Ed and τ w,Ed are evaluated as follows:

i. For Closed sections:

The shear stresses due to warping can be ignored as they will be insignificant and hence:

τ t,Ed = T Ed /(2·Ac·t)

[Ref NCCI Sn007b-EN-EU]

Where:

TEd is the applied torsion,

A c is the area delimited by the mean perimeter and

t is the thickness of the cross section

τ w,Ed = 0, since warping is ignored

ii. For Open sections [I, H, Channel] sections:

For I and H sections, the web will not be subject to warping stresses and therefore warpingshear can be ignored (τ w,Ed=0).

The stress due to pure torsion is evaluated as:

τ t,Ed = G·t·φ’

[Ref SCI pub. P057]

Where:

G is the shear modulus

φ’ is a function depending on the end condition and loading(T). This will betaken from section 6 and Annex B of P057.

Although the maximum stress is at the thickest section of the profile, the program usesthe web thickness for this clause (since the shear capacity is based on the web area)unless the load is parallel to the flanges, in which case the flange thickness is used.

For channel sections that are free to warp at the supports and, thus, are not subject to warpingstresses:

The warping shear stress is evaluated as:

τ w,Ed = E·S w·φ’’’ / t

[Ref SCI pub. P057]

Where:

E is the elastic modulus,

S w is the warping statistical moment and

φ’ is a function depending on the end condition and loading(T). This will betaken from section 6 and Annex B of P057.




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t is the thickness of the element.

Clause 6.2.7(5) – Check for elastic verification of yield

Eurocode 3 gives yield criterion as per eqn. 6.1 and STAAD.Pro uses the yield criterion given in EC -3. When a member is subject to combined bending and torsion, some degree of interaction occursbetween the two effects. The angle of twist caused by torsion is amplified by the bending momentsand will induce additional warping moments and torsional shears. Account must also be taken of theadditional minor axis moments produced by the major axis moments acting through the torsionaldeformations, including the amplifications mentioned earlier.

For members subject to bending and torsion, the stresses are evaluated as follows:

Direct bending stress (major axis): σ bz = M z / Z z

Direct bending stress (minor axis): σ by = M y / Z y

Direct stress due to warping: σ w = E·W ns· φ’’

Direct stress due to twist (min. axis): σ byt = M yt / Z y

Direct stress due to axial load (if any): σ c = P/ A

Where:

Mz is the major axis moment & My is the minor axis moment.

φ’’ is the differential function based on twist (ref P057 Annex B. & Table 6)

W ns is the normalized warping function.

M yt = φ·M z (see Appendix B of P057 to evaluate φ)

Shear stresses due to torsion and/or warping is evaluated as described above for Clause 6.2.7(9).

Check for yield (capacity checks) is then done according to Eqn 6.1 of EN 1993 -1-1:2005, as describedfor the Basic Stress Check (TORSION = 1):

Clause EC-3:6 App A – Check for combined Torsion and Lateral Torsional buckling

The interaction check due to the combined effects of bending (including lateral torsional buckling)and torsion will be checked using Annex A of EN 1993-6: 2007. Note that this interaction equationdoes not include the effects of any axial load.

At present, SCI advises that no significant work has been published for this case and work isstill ongoing. So at present is advisable not to allow for torsion in a member with large axialload.

Members subject to combined bending and torsion will be checked to satisfy:

Where:




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Cmz is the equivalent uniform moment factor for bending about the z-z axis, accordingto EN 1993-1-1 Table B.3.

M y,Ed and Mz,Ed are the design values of the maximum moment about the y - y and z-zaxis, respectively.

M y,Rk and Mz,Rk are the characteristic values of the resistance moment of the cross-section about it y - y and z-z axis, respectively, from EN 1993-1-1, Table 6.7.

M y,cr is the elastic critical lateral-torsional buckling moment about the y - y axis.

T w,Ed is the design value of the warping torsional moment.

T w,Rk is the characteristic value of the warping torsional resistance moment.

χ LT is the reduction factor for lateral torsional buckling according to 6.3.2 of EN 1993-1-1.

For all of the above checks the effective length of the member to be used for torsion can beset by using the EFT design parameter.




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7C.5.4 Members Subject to Torsion

This feature requires STAAD.Pro V8i (SELECTseries 2) build 2007.07 or later.

General

Eurocode 3 (EN 1993-1-1:2005) gives very limited guidance for the analysis and design of torsionmembers. While both elastic and plastic analyses are permitted generally, the design analysis methodsfor torsion discussed within EC3 are primarily based on elastic methods. Also, only the first yielddesign resistance is specifically discussed for torsion members. Furthermore, there is no guidance onsection classification nor on how to allow for the effects of local buckling on the design resistance forcombined torsional effects. EC3 also does not specifically deal with members subject to combinedbending and torsion and loosely states that the yield criteria (Eqn 6.1 in the code) can be used forelastic verification.

The method used by STAAD.Pro is therefore based on the SCI publication “P057: Design of memberssubject to combined bending and torsion”. Though this publication is based on the British standard BS5950-1, the principles from this document are applied in the context of Eurocode 3.

At the time this feature has been implemented in STAAD.Pro, SCI are in the process ofupdating document P057 to be in accordance with Eurocode 3. Hence this method might besubject to modifications subject to the publication of a newer version of P057. The NCCIdocument “SN007b-EN-EU: Torsion” will also be referenced where appropriate.

Code Basis

Torsion design in EC3 is given in Cl. 6.2.7 of EN 1993-1-1:2005. Therefore, this clause is used primarilyfor this implementation.

EN 1993-1-1:2005 does not deal with members subject to the combined effects of torsion and lateraltorsional buckling. However, EN 1993-1-6 considers such a condition in Appendix A. Therefore,STAAD.pro uses Appendix A of EN 1993-1-6 to check for members subject to combined torsion andLTB.

The following clauses from EC3 are then considered:

• Cl. 6.2.7(1)

• Cl. 6.2.7(9)

• Cl. 6.2.7(5)

• EC-3 -6 App A

STAAD.Pro does, however, use this clause (6.2.7) to report the output for all torsion checks. Also any distortional deformations and any amplification in the torsional or shear stressesdue to distortions will be neglected by the program.

• Clause 6.2.7(1)




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States that for members subject to torsion, the design torsional moment TEd at each cross

section should satisfy:

T Ed / R Rd ≤ 1.0

Where:

TRd is the design torsional resistance of the cross section.

This is the primary condition that will need to be satisfied for members subject to torsion. Themethod for working out the torsional resistance TRd, for the various cases is dealt in thefollowing sections.

• Cl. 6.2.7(9)

States that:

For combined shear force and torsional moment, the plastic shear resistanceaccounting for torsional effects should be reduced from V pl,Rd to V pl,T,Rd and thedesign shear force should satisfy:

V Ed / V pl,T,Rd ≤ 1.0

The code also gives means to evaluate V pl,T,Rd in equations 6.26 to 6.28. These equations,

however, only deal with I/H sections, Channel sections, and structural hollow sections (RHS,SHS, CHS). Therefore, the application of Cl. 6.2.7(9) is only performed for these sectionprofiles.

• Cl 6.2.7(5)

States that the yield criteria given in Cl. 6.2.1(5) of EN 1993-1-1:2005 may be used for elastic verification. STAAD.Pro evaluates the stresses due to the various actions on the cross sectionand applies this yield criterion.

The program allows for two types of checks for members subject to torsion for EC3 design:

I. Basic Stress Check: This method is intended to be a simplified stress check for torsional effects.This method will produce the output corresponding to Cl. 6.2.7(5) of EN 1993 -1-1.

II. Detailed Checks: This method will perform a full torsional analysis of the member. All four ofthe clause checks mentioned earlier will be performed.

The details of these checks are as described below.

You have the option to choose the method to be used for a specific member or group of members.This will be facilitated by setting the value of the TORSION. The TORSION parameter set to zero bydefault, which results in torsion checks only being performed if the member is subject to torsional

moments (i.e., for this default setting, the program will ignore torsion checks if there is no torsionalmoment in the member). Setting the value of the TORSION parameter to three (3) will cause theprogram to ignore all torsional moments. The detailed output (i.e., TRACK 2) will indicate that torsionhas been ignored for that particular member. The details of setting the values to one (1) or two (2) andthe corresponding checks performed are as described below. See "Design Parameters" for additionaldetails.

If the TORSION parameter is set to 1 or 2, the program will perform the appropriate checkseven if the member is not subject to torsional moments. In such cases, the program willperform the checks with a value of zero for the torsional moment.

Basic Torsion Stress Checks

Detailed Torsion Stress Checks




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7C.9 Tabulated Results of Steel Design

For code checking or member selection, the program produces the results in a tabulated fashion. Theitems in the output table are explained as follows:

MEMBER

refers to the member number for which the design is performed.

TABLE

refers to steel section name, which has been checked against the steel code or has beenselected.

RESULTS

prints whether the member has PASSED or FAILED. If the RESULT is FAIL, there will be an

asterisk (*) mark on front of the member.

CRITICAL COND

refers to the clause in EN 1993-1-1:2005 code which governs the design.

RATIO

prints the ratio of the actual stresses to allowable stresses for the critical condition.Normally a value of 1.0 or less will mean the member has passed.

LOADING

provides the load case number, which governed the design.

FX, MY, and MZ

provide the axial force, moment in local Y -axis and the moment in local z-axis respectively. Although STAAD does consider all the member forces and moments (except torsion) toperform design, only FX, MY and MZ are printed since they are the ones which are ofinterest, in most cases.

LOCATION

specifies the actual distance from the start of the member to the section where design forcesgovern.

For a TRACK 2 output, the module will also report all the relevant clause checks that havebeen performed and will also indicate the critical ratio and the load case that caused the

critical ratio as well as the corresponding forces that were used for the respective checks. ATRACK 2 output will also include the various design data used for the calculations such as thesection modulii, section class, section capacity etc.

If an NA parameter (other than 0) has been specified and if the particular National Annex requiresadditional checks outside those specified in EN 1993-1-1:2005 (e.g., The Dutch National Annex), therespective NA clauses and any associated code clauses will be listed along with the critical ratios andthe forces that were used for these clause checks.

7C.9.1 Example of a TRACK 2 output

Documentation notes appear in red.

Page 1 of 25B.9 (B) Tabulated Results of Steel Design



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The results and output follow the axis convention as described in Section 7C.1.3

STAAD.PRO CODE CHECKING - BS EN 1993-1-1:2005

********************************************

NATIONAL ANNEX - NA to BS EN 1993-1-1:2005

PROGRAM CODE REVISION V1.9 BS_EC3_2005/1

ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED)

MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/ FX MY MZ LOCATION =======================================================================

1 ST HD320X127 (EUROPEAN SECTIONS)

PASS EC-6.3.3-662 0.045 1

25.00 C 5.00 -10.00 0.00

======================================================================= MATERIAL DATA Grade of steel = USER Modulus of elasticity = 205 kN/mm2

Design Strength (py) = 275 N/mm2 SECTION PROPERTIES (units - cm) Member Length = 500.00 Gross Area = 161.30 Net Area = 161.30

z-axis y-axis

Moment of inertia : 30820.004 9239.001 Plastic modulus : 2149.000 939.100 Elastic modulus : 1926.250 615.933 Shear Area : 81.998 51.728 Radius of gyration : 13.823 7.568 Effective Length : 500.000 500.000

DESIGN DATA (units - kN,m) EUROCODE NO.3 /2005

Section Class : CLASS 1

Squash Load : 4435.75

Axial force/Squash load : 0.006

GM0 : 1.00 GM1 : 1.00 GM2 : 1.10

z-axis y-axis Slenderness ratio (KL/r) : 36.2 66.1 Compression Capacity : 4078.2 3045.5 Tension Capacity : 4435.8 4435.8 Moment Capacity : 591.0 258.3 Reduced Moment Capacity : 591.0 258.3 Shear Capacity : 1301.9 821.3 BUCKLING CALCULATIONS (units - kN,m) Lateral Torsional Buckling Moment MB = 591.0

co-efficients C1 & K : C1 =2.578 K =1.0, Effective Length= 5.000

Elastic Critical Moment for LTB, Mcr = 1541.5 Critical Load For Torsional Buckling, NcrT = 13898.0 Critical Load For Torsional-Flexural Buckling, NcrTF = 13898.0 ALL UNITS ARE - KN METE (UNLESS OTHERWISE NOTED) MEMBER TABLE RESULT/ CRITICAL COND/ RATIO/ LOADING/ FX MY MZ LOCATION ======================================================================= CRITICAL LOADS FOR EACH CLAUSE CHECK (units- kN,m):

CLAUSE RATIO LOAD FX VY VZ MZ MY EC-6.3.1.1 0.008 1 25.0 0.0 0.0 -10.0 5.0

EC-6.2.9.1 0.020 1 25.0 0.0 0.0 -10.0 5.0

EC-6.3.3-661 0.035 1 25.0 0.0 0.0 -10.0 5.0

EC-6.3.3-662 0.045 1 25.0 0.0 0.0 -10.0 5.0

EC-6.3.2 LTB 0.017 1 25.0 0.0 0.0 -10.0 5.0

Torsion and deflections have not been considered in the design. _________________________ ************** END OF TABULATED RESULT OF DESIGN **************

Code title & version

National Annex used, if any

Design engine version

Member number, section profile & table

Design status, critical code clause, & critical ratio

Section forces & critical section location

"z-axis" here refers to bending about Z-Z (when Y is Up), where as EC3 uses the Y-Y axis convention.

Section class as per Table 5.2

Max. cross section capacity (A · f y/GM0

Partial safety factors used

Factor C1 used in Mcr calculations and End restraint factor (corresponds to the CMN design parameters

Max. ratio, loadcase, & section forces for each clause check

Page 2 of 25B.9 (B) Tabulated Results of Steel Design



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7C.6 Design Parameters

Design parameters communicate specific design decisions to the program. They are set to default values to begin with and may be altered to suite the particular structure.

Depending on the model being designed, you may have to change some or all of the parameter default values. Some parameters are unit dependent and when altered, the n setting must be compatible withthe active “unit” specification.

Table 7C.4 lists all the relevant EC3 parameters together with description and default values.

Table 7C.2-Steel Design Parameters EC3 EN

Parameter

Name

Default

Value

Description

CODE - Must be specified as EN 1993-1-1:2005 to

invoke design per Eurocode 3:2005 (EN

1993).

Design Code to follow.

See section 5.48.1 of the Technical

Reference Manual.

ALH 0.5 The ratio of the distance of the point torque(from the start of the member) to the length

of the member. The default value of 0.5

represents torque acting at the mid-span of

a symmetrically loaded member. Values can

range from 0 to 1.

ALPHA 1.0 Used to input a user defined value for the α

factor in equation 6.41 for combined

bending and axial force checks.

BEAM 3Parameter to control the number of sections

to checked along the length of a beam:

1. Check at location of maximum Mz

along beam

2. Check sections with end forces and

forces at location of BEAM 1.0 check.

3. Check at every 1/13th point along the

beam and report the maximum

Page 1 of 13Design Parameters



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Parameter

Name

Default

Value

Description

BETA 1.0 Used to input a user defined value for the β

factor in equation 6.41 for combined

bending and axial force checks.

C1 1.132 Corresponds to the C1 factor to be used to

calculate Elastic critical moment Mcr as per

Clause 6.3.2.2

C2 0.459 Corresponds to the C2 factor to be used to


Clause 6.3.2.2

C3 0 Corresponds to the C3 factor to be used to


Clause 6.3.2.2

CAN 0 Member will be considered as a cantilever

type member for deflection checks.

0 indicates that member will

not be treated as a cantilever

member

1 indicates that the member

will be treated as a cantilevermember

CMM 1.0 Indicates type of loading and support

conditions on member. Used to calculate

the C1, C2, and C3 factors to be used in the

Mcr calculations.

Can take a value from 1 to 8.

Refer to Table 7C.5 for more information on

its use.

CMN 1.0 Indicates the level of End-Restraint.

1.0 = No fixity

0.5 = Full fixity

0.7 = One end free and other

end fixed




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Parameter

Name

Default

Value

Description

CMT 1Used to indicate the loading and support

condition for torsion (ref. SCI publication

P-057).

Can take a value of 1-7. The values

correspond to the various cases defined in

section 6 and App. B of SCI-P-057.

Refer to Table 7C.6 for more information

DFF0

(Mandatory

for deflectioncheck,

TRACK 4.0)

"Deflection Length" / Max.. allowable local

deflection

See Note 1d below.

DJ1Start Joint

of member

Joint No. denoting starting point for

calculation of "Deflection Length" . See Note

1 below.

DJ2End Joint of

member

Joint No. denoting end point for calculation

of "Deflection Length". See Note 1 below.

DMAX 100.0 cm Maximum allowable depth for the member.

DMIN 0 Minimum required depth for the member.

EFT Member

Length

Effective length for torsion. A value of 0

defaults to the member length.

ELB 0 Used to specify the method for combined

axial load + bending checks

0. Uses Cl. 6.2.9 of EN 1993-1-1:2005

1. Uses Cl. 6.2.1(7) - Eqn. 6.2 of EN 1993-

1-1:2005




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Parameter

Name

Default

Value

Description

ESTIFF 0(For use with the Dutch NA only) Method

for checking columns forming part of

(non)/buttressed framework:

0. Checks per Cl 12.3.1.2.3 of NEN 6770:

Section 1

1. Checks per Cl 12.3.1.2.3 of NEN 6770:

Section 2

See "Clause 12.3.1.2.3 (NEN 6770):

Rotation/bending capacity" for additional

description on this parameter.

FAB 3Used to specify the fabrication class to be

used to check for slender (Class 4) CHS/pipe

sections (EN 1993-1-6:2007)

1. Class A – Excellent

2. Class B – High

3. Class C – Normal

FU 0 Ultimate tensile strength of steel.

GM0 1.0 Corresponds to the γm0 factor in EN 1993-

1-1:2005


1-1:2005


1-1:2005




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Parameter

Name

Default

Value

Description

GST 0Used to specify the section type to be used

for designing a “General Section” from the

user table. The member will be consideredas the specified type with the user defined

properties. The available options and

corresponding values are as below:

0. I-Section

1. Single Channel

2. Rectangular Hollow Section

3. Circular Hollow Section

4. Angle Section

5. Tee Section

This parameter will be ignored if it

has been assigned to any section

other than a General Section.

KC 1.0Corresponds to the correction factor as per

Table 6.6 of EN 1993-1-1:2005. Program willcalculate kc automatically if this parameter

is set to 0.

For the British, Singapore, & Polish

NAs, kc will be calculated as given

in the NA by default.

KY 1.0 K factor in local y axis. Used to calculate the

effective length for slenderness and buckling

calculations.

KZ 1.0 K factor in local z axis. Used to calculate the

effective length for slenderness and buckling

calculations.




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Parameter

Name

Default

Value

Description

LEG 0Slenderness values for angles as determined

from BS 5950-2000 Table 25.

See "British Codes - Steel Design per

BS5950:2000"

LVV Max. value of

Lyy

Leg length for Lvv (length about v - v - axis of

single angle section), as per Lyy. Used for

slenderness calculations.

LY Member

Length

Compression length in local y axis,

Slenderness ratio = (KY)*(LY)/(Ryy)

LZ Member

Length

Compression length in local z axis,

Slenderness ratio = (KZ)*(LZ)/(Rzz)

MTH 0Used to select the clause to be used to

calculate the LTB reduction factor, χ LT. The

available options and corresponding values

are as below:

0. Use default method based on sectiontype (default)

1. Use Cl.6.3.2.2

2. Use Cl.6.3.2.3

By default, the program will use Cl 6.3.2.3 for

rolled & built-up I-sections and Cl. 6.3.2.2

for all other sections. If, however, the

specified National Annex expands on Cl.

6.3.2.3 to include other section types (e.g.,

the UK NA), the program will use Cl. 6.3.2.3

by default for that particular section type.

See "European Codes - National Annexes

to Eurocode 3 [EN 1993-1-1:2005]" for

additional details on NA documents.




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Parameter

Name

Default

Value

Description

MU 0To be used with CMM values of 7 and 8. See

Table 7C.4.

Currently valid only with the

French & Belgian NAs.

NA 0 Choice of National Annex to be used for EC3

design. See "European Codes - National

Annexes to Eurocode 3 [EN 1993-1-1:2005]"

for values allowed for this parameter.

(See "National Annex Documents" formore information)

NSF 1.0 Net tension factor for tension capacity

calculation.

PLG 0To be used to determine whether to include

the additional interaction checks as per CL.

NA.20(2) and NA.20(3) of the Polish

National Annex.

This parameter will be applicable

only to the Polish NA

PY Yield

Strength

The yield strength default value is set based

on the default value of the SGR parameter.

RATIO 1 Permissible ratio of loading to capacity.

SBLT 0.0 Indicates if the section is rolled or built-up.

0.0 = Rolled

1.0 = Built-up




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Parameter

Name

Default

Value

Description

SGR 0 Steel grade as in table 3.1 of EN 1993-1-1:2005

0.0 - indicates S 235 grade steel



3.0 - indicates S 420 grade

steel

4.0 - indicates S 460 grade

steel

As EN 1993-1-1:2005 does not

provide a buckling curve in table

6.2 for grade S 450 steel (in Table 3.1

of EN 1993-1-1:2005), the program

will use the same buckling curves as

for grade S 460 when calculating

the buckling resistance as per

clause 6.3.

STIFF MemberLength or

depth of

beam,

whichever is

lesser

Distance between transverse stiffener plates,used to prevent web shear buckling. If not

specified or if a value of 0 is provided, the

program will assume the web is unstiffened.

TOM 0 Total torsion for design used for torsion

checks. Can be used to override the total

torsional moment to be used for member

design.




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Parameter

Name

Default

Value

Description

TORSION 0Method to be used for a specific member or

group of members:

0. Perform basic torsion checks if

member is subject to torsion.

1. Perform basic stress check (Ignore

warping effects).

2. Perform detailed checks (including

warping effects).

3. Ignore all torsion checks

For options 1 or 2, the program willperform the torsion related checked

even if torsional moment is absent

and will use a value of zero for the

torsional moment.

TRACK 0Specify level of detail in output.

0. Summary of results only.

1. Summary with member capacities.

2. Detailed results.

4. Deflection check results only.

UNF 1 Unsupported length as a fraction of the

actual member length.

UNL Member

Length

Unrestrained length of member used in

calculating the lateral-torsional resistancemoment of the member.

ZG +Section

Depth/2 Distance of transverse load from shear

center. Used to calculate Mcr.

For Tee sections, ZG will have a

default value of (+Flange

thickness/2)

Notes:




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1. CAN, DJ1, and DJ2 – Deflection

a. When performing the deflection check, you can choose between two methods. The firstmethod, defined by a value 0 for the CAN parameter, is based on the local displacement.Local displacement is described in Section 5.44 of the Technical Reference Manual.

If the CAN parameter is set to 1, the check will be based on cantilever style deflection. Let(DX1, DY1, DZ1) represent the nodal displacements (in global axes) at the node definedby DJ1 (or in the absence of DJ1, the start node of the member). Similarly, (DX2, DY2,DZ2) represent the deflection values at DJ2 or the end node of the member.

Compute Delta = SQRT((DX2 - DX1)2 + (DY2 - DY1)2 + (DZ2 - DZ1)2)

Compute Length = distance between DJ1 & DJ2 or, between start node and end node, asthe case may be.

Then, if CAN is specified a value 1, dff = L/Delta

Ratio due to deflection = DFF/dff

b. If CAN = 0, deflection length is defined as the length that is used for calculation of localdeflections within a member. It may be noted that for most cases the “DeflectionLength” will be equal to the length of the member. However, in some situations, the“Deflection Length” may be different. A straight line joining DJ1 and DJ2 is used as thereference line from which local deflections are measured.

For example, refer to the figure below where a beam has been modeled using four jointsand three members. The “Deflection Length” for all three members will be equal to thetotal length of the beam in this case. The parameters DJ1 and DJ2 should be used tomodel this situation. Thus, for all three members here, DJ1 should be 1 and DJ2 shouldbe 4.

D = Maximum local deflection for members 1, 2, and 3.

PARAMETERS

DFF 300. ALL

DJ1 1 ALL

DJ2 4 ALL

c. If DJ1 and DJ2 are not used, "Deflection Length" will default to the member length andlocal deflections will be measured from original member line.

d. It is important to note that unless a DFF value is specified, STAAD will not perform adeflection check. This is in accordance with the fact that there is no default value forDFF (see Table 2B.1).

e. The above parameters may be used in conjunction with other available parameters forsteel design.

2. CMM Parameter

The values of CMM for various loading and support conditions are as given below:

Table 7C.3- Values for the CMM Parameter

CMM Value Loading and Support Conditions




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CMM Value Loading and Support Conditions

1

2

3

4

5

6

7

varying end moments and uniform loading

8

varying end moments and central point load

3. Checking beam deflection

With the TRACK parameter set to 4, the members included in a BEAM CHECK command will bechecked for the local axis deflection rather than for the stress capacity using the current LOADLIST.

If both stress capacity and deflection checks are required, then 2 parameter blocks with codechecks are required, one with a TRACK 4 command and one with a TRACK 0, 1 or 2, thus:

LOAD LIST 1 TO 10

PARAMETER 1

CODE EN 1993

TRACK 2 ALL

CODE CHECK MEMBER 1

***************************

LOAD LIST 100 TO 110

PARAMETER 2

TRACK 4 ALL

DFF 300 MEMB 1

DJ1 1 MEMB 1DJ2 4 MEMB 1

CHECK CODE MEMB 1




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While both sets of code checks will be reported in the output file, only the last codecheck results are reported in the STAAD.Pro graphical interface.

4. CMT Parameter

The values of CMM for various loading and support conditions are as given below:

Table 7C.4-Loading and Support Conditions represented by CMT Parameter Values

CMT

Value

Description Diagram

1 (Default) : Concentrated Torque atEnds. Ends Torsion fixed and Warping fixed

2 Concentrated Torque along length ofmember. Ends Torsion fixed and Warping free

3 Concentrated Torque along length ofmember. Ends Torsion fixed and Warping fixed

4 Uniform Torque in member. EndsTorsion fixed and Warping free

5 Uniform Torque in member. EndsTorsion fixed and Warping fixed

6 Concentrated Torque in cantilever.End Torsion fixed and Warping fixed

7 Uniform Torque in cantilever. EndTorsion fixed and Warping fixed

For CMT = 2 and CMT = 3, you have the option of specifying the distance at which theconcentrated torque acts, measured from the start of the member. This can be done byusing the ALH design parameter. The ALH parameter indicates the ratio of the distanceof the point torque (from the start of the member) to the length of the member. Thisparameter will have a default value of 0.5 (i.e., the torque acts at the center of the

span) and will accept values ranging from 0 to 1.




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The GB1 parameter that is being used for compression checks in builds preceding this release(STAAD.Pro 2007 build 06) has been removed as this parameter is no longer required in EN1993-1-1:2005. Hence any legacy files that use GB1 parameter will indicate an error messageand you will be required to substitute GB1 with GM1, in accordance with EN 1993-1-1:2005.
