Analysis in staad pro

Sir,

I am new for Staad Pro. Kindly elaborate about some points:  

1. When We should use P Delta Analysis instead of Perform analysis?

2. Here Three options in P Delta Analysis a) Converge b) Use geometric stiffness (KG)  c) Small Delta. When and how use these options?

3. It is necessary to keep seismic load cases above (before) all load cases? Means load case number 1 to 4 should be for EQ X, EQ -X, EQ Z, EQ -Z?

4. What should be the location of wind load in load cases? before or after Dead Load and Live Load cases?

5. I have some load combinations like:

1.5 DL+1.5 LL
1.2 DL +1.2 LL +1.2 WLX
1.2 DL +1.2 LL +1.2 WL-X
1.2 DL +1.2 LL +1.2 WLZ
1.2 DL +1.2 LL +1.2 WL-Z
1.2 DL +1.2 LL +1.2 ELX
1.2 DL +1.2 LL +1.2 EL-X
1.2 DL +1.2 LL +1.2 ELZ
1.2 DL +1.2 LL +1.2 EL-Z
1.5 DL + 1.5 WLX
1.5 DL + 1.5 WL-X
1.5 DL + 1.5 WLZ
1.5 DL + 1.5 WL-Z
1.5 DL + 1.5 ELX
1.5 DL + 1.5 EL-X
1.5 DL + 1.5 ELZ
1.5 DL + 1.5 EL-Z
0.9 DL + 1.5 ELX
0.9 DL + 1.5 EL-X
0.9 DL + 1.5 ELZ
0.9 DL + 1.5 EL-Z

Should I use REPEAT LOAD command for all above load combinations for P Delta analysis or I should use REPEAT LOAD command for (1.5 DL + 1.5 LL) combination and for remaining I can use load combination command?

6. How can I give these commands after P DELTA (n) ANALYSIS SMALL DELTA:

PRINT PROBLEM STATISTICS
PRINT ELEMENT INFORMATION ALL
PRINT MATERIAL PROPERTIES ALL
LOAD LIST ALL
PRINT SUPPORT REACTION LIST 1 TO 10
PRINT ELEMENT FORCE ALL
PRINT STORY DRIFT

7. what value of (n) is sufficient in P DELTA (n) ANALYSIS SMALL DELTA?

  • 1. When you are trying to account for second order effects.

    2. Please use the PDELTA nn ANALYSIS or PDELTA nn ANALYSIS SMALLDELTA. Both are same as smalldelta effects are included by default. The nn stands for the number of iterations and it is enough to go for about 20 iterations. All options are explained in the Help documentation. I would not suggest using the CONVERGE.

    3. Correct if these seismic loads are equivalent static load generations. If you are using Response Spectrum or Time History, the order does not matter.

    4. Could be located anywhere.

    5. Loads should always be combined using REPEAT LOADs when you are using the PDELTA ANALYSIS. You should not use LOAD COMBINATION.

    6. You can use the command editor to paste these commands after the analysis command or if you are asking how to enter these through the graphic user interface, here are the locations where you will find these commands

    7. 20 is generally a good value.  



    Answer Verified By: Surendar Rao