Comparative study of special and ordinary braced frames

摘要

The collapse probability of ductile and non-ductile concentrically braced frames was investigated usingnnonlinear dynamic response analysis. Two buildings with three and nine stories located in Boston andnLos Angeles, respectively, were designed and subjected to ground motions from the areas. In Boston area,nthree-story and nine-story buildings were designed as ordinary concentrically braced frame withnresponse modification reduction factor R equal to 3 1/4 to be considered as non-ductile structural systems;ncomparatively, in Los Angeles area, three-story and nine-story buildings were designed as specialnconcentrically braced frame with response modification reduction factor R equal to 6 to be considerednas ductile structural systems. In order to evaluate the performance of ductile and non-ductile concentricallynbraced frames in moderate and severe seismic regions, ATC-63 would be used as reference to assess thenseismic behaviors. Evaluation approach recommended by ATC-63 was adopted, and hundreds of nonlinearndynamic analyses were performed. Through alternating the scale factors of designated ground motions, mediannof structural collapse intensity was presented for each structure. By observing the results of statisticalnperformance assessment, the seismic performance of the systems was evaluated, and some observationsnare made based on the study. Copyright © 2012 John Wiley & Sons, Ltd.