Knee Braced Frame for Seismic Load

[emanon40]

Can a Knee Braced Frame be used to Resist Lateral Seismic Load in Seismic Design Category D ? ie California?

Thanks for your help.

Chris

 

[msquared48]

Don't know about the big C, but in WA knee braces are used all the time in residences and decks for lateral resistance. I'm in a category D area too.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[emanon40]

Thanks Mike,

We have always submitted plans using knee braces as seismic force resisting systems for non building structures here in So Cal.

Plan checker refuses to allow use of knee brace as a seismic force resisting system because it is not listed in table 15.4-1 & 2 of ASCE 7.05.

Don't really want to use Chevron Bracing because of obstructions. Any advice?

 

[msquared48]

Pole footing or moment frame?

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[sandman21]

Knee braces are considered OMF they are acceptable in CA as long as the limitations of ASCE are followed. Point the plan checker to AISC 341 section C11.1 page 6.1-170.

 

[JoshPlumSE]

If your structure is less than 50 feet tall, then you should be allowed to do it.... You just might have to refer to the structure as the option for "all other...". You get penalized a bit with your R and your Omega. But, that's probably as it should be.... After all, these knee braces frames are not exactly known for ductile behavior.