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use of knee bracings in steel framed seismic zone 4?
dear pals
most of us here use codes with judgement. what is your reaction to a design which includes a special moment frame in seismic zone 4(the most intense to ubc97 or ibc2000) reinforced with knee braces? by knee braces i mean a diagonal elements placed around 45 degrees to the column connecting both column and beam below floor level. without this brace the beam-column connection would be a pure moment connection/shear.
i am personally against this use of knee brace. dont they present an action similar to the prohibited k braces?. are they pre-qualified. by pre-qualification i mean any structural system or connection configuration that has been well tested/researched and known to perform well for a specified use.
your input will be highly appreciated.
respects
ijr
check out our whitepaper library.
i have not purchased the paper, but knee braces appear to have been researched for this application and, according to the abstract, can be made to work. here is a link
i personally prefer to not use knee braces for main lateral force bracing. they can be made to work, but it has to be done carefully. with certain geometries you will get tremendous, unrealistic axial loads in the braces.

2009-09-16, 05:45 PM	#1
huangyhg 超级版主注册日期: 04-03 帖子: 18592 精华: 36 现金: 249466 标准币资产: 1080358888 标准币	use of knee bracings in steel framed seismic zone 4 use of knee bracings in steel framed seismic zone 4? dear pals most of us here use codes with judgement. what is your reaction to a design which includes a special moment frame in seismic zone 4(the most intense to ubc97 or ibc2000) reinforced with knee braces? by knee braces i mean a diagonal elements placed around 45 degrees to the column connecting both column and beam below floor level. without this brace the beam-column connection would be a pure moment connection/shear. i am personally against this use of knee brace. dont they present an action similar to the prohibited k braces?. are they pre-qualified. by pre-qualification i mean any structural system or connection configuration that has been well tested/researched and known to perform well for a specified use. your input will be highly appreciated. respects ijr check out our whitepaper library. i have not purchased the paper, but knee braces appear to have been researched for this application and, according to the abstract, can be made to work. here is a link i personally prefer to not use knee braces for main lateral force bracing. they can be made to work, but it has to be done carefully. with certain geometries you will get tremendous, unrealistic axial loads in the braces. __________________ 借用达朗贝尔的名言：前进吧，你会得到信心! [url="http://www.dimcax.com"]几何尺寸与公差标准[/url]