STAAD DEFLECTION/STREGTH FOR DIFFERENT LOAD CASES

November 21, 2013, 11:18 pm

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I have a model for which I am using parameter command to carry out seperate Strength & Deflection check. However when I check the utilisation it shows it being critical for deflection, however the utilisation for strength is more critical but has been over written by that of deflection as it was the second code check. If I revesre the poition of the deflection & stregth check them the reverse happends.

How can I set up my command file to get the most critical utilisation for the approprite load case. I have check this by carrying out the two check in seperate file but when I combine them the command file I am using does not force the program to select the most critical govering cluase Deflection/strength.

Another question why STAAD give different result if you use

CODE AISC UNIFIED 2010 METHOD LRFD

rather than

CODE AISC LRFD

i.e. what version if AISC LRFD it is using to check memeber if above command is used

Here is my file (attached)

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LRFD versions?

November 21, 2013, 11:55 pm

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Can someone kindly tell me the difference between these two commands

CODE AISC UNIFIED 2010

METHOD LRFD

&

CODE LRFD

Why I get different utilization values?

What version of the code the program would be using if i just specifies CODE LRFD?

Tension only members STAAD pro

November 22, 2013, 9:07 am

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When using member tension, may I use load combinations or they would need to be changed for the repeat command and perform analysis on each of them. Version I have is release 20.07.05.15

How to run OpenStaad Application Object in Modal mode

November 22, 2013, 1:45 pm

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The RESULTS Object with .analyze() function used to be modal where once the command is issued from vb6 staad would run and the vb program will wait till Staad finishes.

In The APPLICATION Object, this function is not modal and execution continues in the VB application causing errors.

I put a msgbox and asks the user to click ok when Staad finishes running, is there another way?

Thanks

M.Helweh

"Application Object" .vs. "Results OBject" Speed

November 22, 2013, 1:54 pm

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I am forced to convert from the "Results Object" to the "Application Object" but the difference in speed is huge and the Application Object runs very very slow compared to the other.

Any Ideas why?

Can we get the "Results Object" updated and maintained accordingly as the "Applications Object" since it is much faster and has many functions not present in the "Applications Object". We should be going forward not backwards!!!!!!!!!

The "Results Object" still works but according to Bentley it was designated as obselete and no further development or support will be applied to it.

Thanks, Mike

response spectrum analysis in STAAD

November 22, 2013, 8:39 pm

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Hi

Three questions regarding the response spectrum analysis. 

Q1:
I am not quite sure why I got zero on the Y and Z directions?  Please advise.

LOAD 4 LOADTYPE
Seismic  TITLE RESP. SPECTRUM LOADS X

MEMBER LOAD

15 TO 20 35 TO 40 UNI
GX 10

15 TO 20 35 TO 40 UNI
GY 10

15 TO 20 35 TO 40 UNI
GX 200

15 TO 20 35 TO 40 UNI
GY 200

5 6 25 26 UNI GX 150

5 6 25 26 UNI GY 150

SPECTRUM SRSS IBC 2006
X 1 ACC DAMP 0.05

ZIP 2908 SITE CLASS D
FA 1.600 FV 2.400 TL 6.000

SELFWEIGHT X 1 LIST 5 6
15 TO 20 25 26 35 TO 40

SELFWEIGHT Y 1 LIST 1
TO 4 7 TO 14 21 TO 24 27 TO 34

SELFWEIGHT Z 1 LIST 41
TO 52

*

PERFORM ANALYSIS

CHANGE

*

LOAD 5 LOADTYPE
Seismic  TITLE RESP. SPECTRUM LOADS Y

MEMBER LOAD

15 TO 20 35 TO 40 UNI
GX 10

15 TO 20 35 TO 40 UNI
GY 10

15 TO 20 35 TO 40 UNI
GX 200

15 TO 20 35 TO 40 UNI
GY 200

5 6 25 26 UNI GX 150

5 6 25 26 UNI GY 150

SPECTRUM SRSS IBC 2006
Y 1 ACC DAMP 0.05

ZIP 2908 SITE CLASS D
FA 1.600 FV 2.400 TL 6.000

SELFWEIGHT X 1 LIST 5 6
15 TO 20 25 26 35 TO 40

SELFWEIGHT Y 1 LIST 1
TO 4 7 TO 14 21 TO 24 27 TO 34

SELFWEIGHT Z 1 LIST 41
TO 52

*

PERFORM ANALYSIS

CHANGE

*

LOAD 6 LOADTYPE
Seismic  TITLE RESP. SPECTRUM LOADS Z

MEMBER LOAD

15 TO 20 35 TO 40 UNI
GX 10

15 TO 20 35 TO 40 UNI
GY 10

15 TO 20 35 TO 40 UNI
GX 200

15 TO 20 35 TO 40 UNI
GY 200

5 6 25 26 UNI GX 150

5 6 25 26 UNI GY 150

SPECTRUM SRSS IBC 2006
Z 1 ACC DAMP 0.05

ZIP 2908 SITE CLASS D
FA 1.600 FV 2.400 TL 6.000

SELFWEIGHT X 1 LIST 5 6
15 TO 20 25 26 35 TO 40

SELFWEIGHT Y 1 LIST 1
TO 4 7 TO 14 21 TO 24 27 TO 34

SELFWEIGHT Z 1 LIST 41 TO
52

*

PERFORM ANALYSIS

CHANGE

 

Q2:
 The base shear results are less on the load case #1 (Seismic X) compared to load #4 (Response Spectrum in X).  Why?  I thought that the static analysis (V=Cs*W) shall be conservative compared to the dynamic analysis, right?  Please advise. 

 

Q3:
 Why I got same results on the repeat load (load case #7) and load combination (load case #8)?  Please advise.

Thanks again for the help.

 

Discrepancy in sheaar results in plate.

November 22, 2013, 10:08 pm

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I am experiencing a discrepancy in a beam plate model. The SQx and SQy values in the model are decreasing with decreasing plate thickness.

StaadPro - Effective Length For Compression Chords In Long Trusses

November 23, 2013, 9:41 am

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I have designed a 80m box truss with StaadPro. For the top chords that are in compression, do I need to specify their Lz to be equal to 80m? If I do that, the top chords will fail terribly due to slenderness. Is it a valid assumption to default the Lz for the top chords to the member length between nodes in this circumstance?

I have attached the relevant file; will appreciate some advices.

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STAAD PRO HELP: Weird Error Message

November 24, 2013, 9:40 pm

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Hey guys,

I'm new to this program.  I'm trying to use STAAD to analyze a bridge for my university's ASCE team.  I'm trying to view the stresses due to the self weight so I can take a look at the stress distributions of the bridge, however, I keep getting the following message when I try to run the analysis:

   ** ERROR : A VALID REFERENCE LOAD CASE NUMBER IS NOT SPECIFIED IN THE ABOVE LINE. **

The ONLY load I'm using is self weight.

Any ideas?

Thank you.

BS Code Check

November 25, 2013, 9:31 am

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Hello Sirs

 I have a question regarding the BS code check. Studying the help files, I found that the ESTIFF parameter is set is 0 as the basic value. Shouldn’t it take 1 as the basic value and report the maxium ratio?

Clauses 4.8.3.3.1 and 4.8.3.3.2

0.0 = Fail ratio uses MIN of 4.8.3.3.1, 4.8.3.3.2. and Annex I1 checks.

1.0 = Fail ratio uses MAX of 4.8.3.3.1, 4.8.3.3.2. and Annex I1 checks.

 

Appreciate your kind help.

 

Rike.

RAM Elements - Diaphragm modeling

November 25, 2013, 11:27 am

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I would like to use shell elements to model a diaphragm. However, all I need the diaphragm for is stability and to distribute gravity forces. I have read through the article regarding semi-rigid diaphragms and RAM Frame. Now applying that to RAM Elements, if I understand correctly, I can use a very thin shell to reduce any type of 'flange action' that would occur due to the stiffness of the shell and connection to the beams. Is this correct or is there a better way to Model this? Is there a way to have the shell distribute loads (not using an area) and provide stability to nodes yet not contribute to the resisting applied forces? 

Thanks!

Lateral-Torsional Buckling Modification Factor verification

November 25, 2013, 10:16 pm

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Hi! I'm using RAM Elements and I want to verify manually if the correct cb was given to me for AISC-Design Guide 25-Frame Design Using Web-Tapered Members because there was one instance that the cb reported was less than 1.0 (but I cannot generate the same report now).

Where can I get the stresses for f2, f0 and fmid so that I may compute cb manually and compare?

CLAUSE IN STAAD PRO

November 26, 2013, 7:06 am

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I have a number of beam in my model and when i run a unity check some fail by different "clauses" Below are all the list clauses that i am coming up with.

clause h1/2

clause h3

clause g

clause e2

Does anyone know where i can find a definition of these "clauses".

Thank you

Input seismic analysis as per IS 1893

November 26, 2013, 2:36 pm

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Dear Sanjib Das / Or any one from Bentley

Would u please explain the terms mentioned in my earlier post  dated 20 Nov. 2013?

KPL

Star bracing in staad

November 26, 2013, 10:21 pm

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Dear Forum members,

When I use star bracing members in my structure, design not supported for these. could you please guide? I'm using LRFD design code in staad.

 

 

BR

LB

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Runtime error '-2147417848 (80010108)': Method 'SelectSTADDFILE' of object 'IOutput' failed

November 27, 2013, 8:03 am

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Hi everyones, my code is like this but something wrong again . VBA Excel macros results in a debug message at line " objOpenSTADD.SelectSTAADFile

strfilename " . Pls. help me how to fix it correctly. ( I have opened an executable Stadd program to run macros already )

Been trying so hard for days but no solutions. Waiting for our gurus @@

Option Explicit

Sub section()
    
Dim objOpenSTADDGUI As Object

Dim objOpenSTADD As Object





Set objOpenSTADD = CreateObject("OpenSTAAD.Output.1")

Set objOpenSTADDGUI = GetObject(, "StaadPro.OpenSTAAD")

Dim strfilename As String
 




objOpenSTADDGUI.GetSTAADFile strfilename, True

Cells(1, 1).Value = strfilename

objOpenSTADD.SelectSTAADFile strfilename

Sheets("Section").Select

................................

        objOpenSTADD.CloseSTAADFile

        Set objOpenSTADD = Nothing
        
        Set objOpenSTADDGUI = Nothing

End Sub

section properties problem in STAAD Pro

November 27, 2013, 8:52 am

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Hai friends

 

Please help us to solve problem with STAAD section informations. Staad developers kindly advice us. All query mentioned in the attached word file

 

Thanks for ur support in advance

 

Regards

Bagmass

AISC 360-2010 Code Check Ratio Question on STAAD Pro V8i

November 27, 2013, 10:00 am

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Hello,

I am new to this forum, so I apologize if this has already been asked. I made a simple model on STAAD to check and compare the results with my hand calculations. I used AISC 360-10 code checks, and on the attached model, the Unity Check ratio on Beam 1 is 1.44 from Eq. H1-1a. When I calculated this ratio by hand I get 1.53, and when I switch to AISC 360-05, it comes out as 1.53 as well.

Can someone please explain where the difference in ratio values is coming from?

Thank you.

Colum Design Error

November 27, 2013, 10:13 pm

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When using the BS 8110 code for design, I am getting the error:

 

Loading 1 produces tension in member 1. Check suitablility of design.

 

And the design is not being performed.

 

Staad Guys(Shany), please help.

Thank You.

Problem in steel modeling

November 28, 2013, 12:57 am

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I am attaching a model. There the vertical members require lesser section properties than the bracings. Where is the problem please let me know. Also what does the warning mean and what is its effect in analysis.