RESEARCH ON SEISMIC COLLAPSE MARGIN RATIO OF V-SHAPE CBSF CONSIDERING STRUCTURAL INFLUENCING COEFFICIENT

Five typical V-shape concentrically braced steel frames ( CBSF) in zones of seismic intensity VII were designed and their seismic safety was studied according to seismic collapse assessment system of FEMA P695． The results show that the CBSFs based structural influencing coefficientR=3. 2 possess enough anti-collapse capacity， can provide safe room，furthermore，they possess stronger anti-collapse capacity than that ofno callapse in strong earthquake，so that their collapse probability can be accepted under specially strong earthquakes，which can be used in seismic performance-based design．