NCEES Practice Exam Lateral #125

[Duke]

Shouldn't the answer be the 'lesser' of the two forces and be A not D? What am I missing? Thanks

 

[clutchmoves2022]

I was confused about this too.
Check out these threads:

NCEES Sample Exam, Lateral AM, Problem 125 (Pg 160 & Pg 211)

Follow-up - NCEES SE Practice Exam - Lateral Questions 124 & 125

TL;DR: The brace connection must be strong enough to either fully develop a hinge in the brace, or accommodate the largest force that could (possibly) be developed in the brace (e.g. through use of some sort of capacity-limiting mechanism). The minimum applies to these two values, but for braces without some special capacity-limiting mechanism (most cases), the expected yield strength governs. This is poorly worded in SDM F2-6c for SCBFs.

Choice A (71 k) is incorrect, since this is the raw demand obtained from analysis. Ω*71 = 142 k would seem logical, however, this is also incorrect, since theoretically, the brace may still be able to deliver a larger force to the connection. Basically, we need to design the brace connection as a capacity-protected element.

Hope this helps! GL!