Hi;
My Question is the parameter FLEX should = 0.8 or 1.0 in STAAD PRO while define the direct analysis parameters. as i was reviewing the Discussions that arranged behind the same subject and i can find most of PPL is considered FLEX =1.0 and no comment from Bentley technical team on that. So can you confirm this parameter which value needs to consider.
FLEX is the initial τb value (See Chapter C of AISC 360-10/16 or Appendix 7 AISC 360-05). Members listed with FLEX will have their EI factored by 0.80 times τb while performing the global solution. The default value of τb is 1.0 but user can define the initial approximate τb value. You can find more details on this topic in these Wikis:
communities.bentley.com/.../flex-and-taub
communities.bentley.com/.../direct-analysis-and-its-implentation-in-staad-pro