Include Load Factors in P-Delta analysis?
Include Load Factors in P-Delta analysis?
(OP)
I am designing a slender column, and have a question about whether or not to include factored loads when doing a p-delta analysis (with Staad). I was told that it would be like factoring it twice, since the 'delta' would be from factored loads, and I should use unfactored loads to obtain 'delta', which makes sense, but I feel like the factors are there for the uncertainty in actual load conditions, and thus the factored 'delta' could very well occur. Does anyone have any opinion on this, or better yet, point to the location in a code for better direction?
Thanks in advance.
Thanks in advance.






RE: Include Load Factors in P-Delta analysis?
Carl Bauer
RE: Include Load Factors in P-Delta analysis?
I was wondering as to why u need to carry out Pd rather than a normal perform analysis.
Maybe u let us know more about your slender columns and structure it has to support.
RE: Include Load Factors in P-Delta analysis?
RE: Include Load Factors in P-Delta analysis?
I would be inclined to carry out the analysis & design as follows:
1. Factor all the loads and carry out a normal perform analysis command.
2. Member sizing based on the results from above.
3. 2nd Order analysis with factored loads imposed on the columns. Invoke a PDelta analysis command.
4. Revisit your design with deflections/displacements obtained from 3 above to check for additional moments.
How r your columns connected?
Do u have any bracing in place?
How high r your columns?, size? Slender??