Regarding PDELTA Analysis Syntax on STAAD, I understand that STAAD automatically considers small and large delta effects (B1 and B2).
For us to use PDELTA Analysis to simulate second order analysis correctly can you please confirm if STAAD automatically calculate effective length factor of a member?
If STAAD automatically considers effective length factor, this allow user not to declare k value of member on parameter declaration.
Per AISC 360-10, effective length factor is required for second order analysis.
When you use a PDELTA ANALYSIS command in STAAD.Pro, the effective length factors are NOT calculated automatically. However, if you use a PERFORM DIRECT ANALYSIS command, the program will use a Direct Analysis Method (PDelta analysis is included), which does not require effective length factors.
Answer Verified By: Violet
Hello, Thank you for your answer.
If so effective length factor are NOT calculated automatically.
I am mislead on this article, could you reverify this if this is already void?
Automatic calculation of effective length factors Ky and Kz in STAAD.Pro - RAM | STAAD | OpenTower Wiki - RAM | STAAD | OpenTower - Bentley Communities
When you select KY or KZ design parameter in the AISC ASD code, there is an option to Calculate the K value. The calculation of the effective length factor is carried out as per a paper titled “Compression Members” by George Tsiatas. It is not related to the PDELTA analysis.
Hello, Thank you very much for your answer.
Using AISC ASD code in design parameters, instruct STAAD to calculate automatically ky and kz design value and STAAD calculation of k value is based on AISC nomograph and I think this is also same with paper of George Tsiatas that you had mentioned., Is my understanding correct?
Also, in simulation of 2nd order analysis, calculation of k value on same nomograph is required.
If my understanding is correct, using AISC ASD code in design parameters with PDELTA Analysis simulates 2nd order effect without any required k value declaration.
You can use a PDELTA ANALYSIS and use the 'Calculate' option for the KY and KZ design parameters in the AISC ASD code. This calculator will calculate the K factors automatically and you will just need to assign it to the member.