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Staad Pro Topic

 
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thirumalaichettiar
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PostPosted: Fri Jul 23, 2010 1:04 am    Post subject: Staad Pro Topic Reply with quote

Dear Admin,

Is it possible to arrange the STAAD PRO postings the one like the topics on BOOKS and Seismic references? It may be useful if it is arranges under STICKY and at the top of the postings?

T.Rangarajan.
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thirumalaichettiar
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PostPosted: Sat Jul 24, 2010 3:04 am    Post subject: Reply with quote

Dear Sefians,

If you search with the word STAAD PRO there are 675 postings in the forum which are scattered and some of them are of only for discussion. Some of them useful for learning. If the Admin makes it as sticky of this one hope to collect the link in this and put it for the convenience of all.
Expect a go  from Admin.

T.Rangarajan.
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thirumalaichettiar
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PostPosted: Sat Jul 24, 2010 3:16 am    Post subject: Repeat Load and Load Combination Reply with quote

What is the difference between REPEAT LOAD and LOAD COMBINATION in Staad?

ANS:
Normally, if you are doing a linear static analysis-which is what a PERFORM ANALYSIS commnand does-it should make no difference whether you specify REPEAT or COMBINATION. However, if you are doing a PDELTA analysi, or NONLINEAR analysis, or cases involving MEMEBER TENSION and MEMBER COMPRESSION (as in the case of TRUSS DESIGN) etc, it matters. That is because, in those situations, the results of those individual cases acting simultaneously IS NOT the same as the summation of the results of those individual cases acting alone. In other words,

(Results of Load A)+(Results of Load B) is not equal to ((Results of Load(a+B)).

Take the case of P-Delta analysis. The P-Delta effect comes about from the interaction of the vertical load and the horizontal load. If they do not act simultaneously, there is no P-Delta effect. And the only way to make them act simultaneously is to get the program to compute the displacement with both loads being present in a single load case.

A REPEAT LOAD case achieves that.

A LOAD COMBINATION load case does not.

Engineer Va being expert can comment more on this.

T.Rangarajan.
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TYL
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PostPosted: Fri Feb 05, 2016 12:50 pm    Post subject: Re: Repeat Load and Load Combination Reply with quote

thirumalaichettiar wrote:
What is the difference between REPEAT LOAD and LOAD COMBINATION in Staad?

ANS:
Normally, if you are doing a linear static analysis-which is what a PERFORM ANALYSIS commnand does-it should make no difference whether you specify REPEAT or COMBINATION. However, if you are doing a PDELTA analysi, or NONLINEAR analysis, or cases involving MEMEBER TENSION and MEMBER COMPRESSION (as in the case of TRUSS DESIGN) etc, it matters. That is because, in those situations, the results of those individual cases acting simultaneously IS NOT the same as the summation of the results of those individual cases acting alone. In other words,

(Results of Load A)+(Results of Load B) is not equal to ((Results of Load(a+B)).

Take the case of P-Delta analysis. The P-Delta effect comes about from the interaction of the vertical load and the horizontal load. If they do not act simultaneously, there is no P-Delta effect. And the only way to make them act simultaneously is to get the program to compute the displacement with both loads being present in a single load case.

A REPEAT LOAD case achieves that.

A LOAD COMBINATION load case does not.

Engineer Va being expert can comment more on this.

T.Rangarajan.


Very well said....I always use Repeat Load rather than load combination. It is important that engineers understand the difference between repeat load and load combination especially when doing tension-only structure or nonlinear analysis.
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