Evaluation of sensitivity of CBFs for types of Bracing and story numbers

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Abstract

Recently, there has been lots of studies about ductility reduction factor of CBFs, because AISCs seismic design provision has been changed significantly since 2010, So a comprehensive study is needed for seismic designing and ductility reduction factor of CBFs. In this study, about 160, 2D CBFs with different types of bracing  are designed according to AISC-341, and ductility reduction factor of designed  frames  is compared for types and form of bracing in the height of frames. The results confirm that ductility reduction factor and response modification factor of CBFs, are mostly dependent on types and form of bracing. Also, maximum allowable height of OCBFs Can  be reduced  for some types of bracing and increased for some other types of bracings. for SCBFs ductility reduction factor  depends on the bracing type and number of frame stories. For most of studied SCBFs, ductility reduction factor can't be achived  for more than  ten-story frames, so for these kind of  frames, maximum allowable height should be decreased or smaller response modification factor should be used. For double large scale CBFs, Because of the enormous stiffness of  one to seven story frames, ductility reduction factor can't be obtained and smaller response modification factor should be used.

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