Tension bracing system

[brsd]

I'm trying to pull building permits for my two story steel framed addition in Encinitas, CA. After 8 mos in and out and in "plan checking" phase I am down to one last correction. I would be very greatful for your expert advise in clarifying the issue listed below. (The original engineer of my plans can not be located).
The City of Encinitas says this:
"Please clarify why? In the structural design calculations an R value of 6.5 was used. The Lateral resisting system appears to be tension only bracing. Tension only bracing systems shall be designed with an R value of 2.8."
Thank you very much.

 

[Taro]

In layman's terms, frames with braces that are designed to resist both tension and compression perform better than frames with braces that can resist tension forces only. Therefore, the tension-only system is penalized with higher design forces. The specific coefficients cited seem to be off, but the intent is to design the frames for "overstrength" forces so they will sustain less damage.

This could be a major design revision. If the original engineer is not around, you should find another structural engineer to do the redesign. The new engineer most likely will need to review the entire design, not just resize the braces.

 

[ahmad777643]

i agree