ASCE 7-5 seismic question 1

[structuralnerd]

In ASCE 7-05 section 12.4.3, it talkes about including the seismic overstrength factor where conditions require it. When is that factor specifically required, and when do you use the normal seismic equations shown in section 12.4.2?

 

[JAE]

Here are some threads on that subject:

thread487-204811

thread172-185459

thread726-126245

thread487-205844

thread176-140534

The overstrength combinations are sprinkled throughout the codes, specifically they are used to beef up those elements or connections that have brittle failure modes vs. ductile modes. They attempt to ensure that the weak link in the chain is a ductile failure that will use up the energy and avoid catastrophic collapse.

You have to read through all the specific design requirements in the code to find where they are required.