Evaluation on Seismic Performance of Dual Steel Moment-Resisting Frame with Zipper Bracing System Compared to Chevron Bracing System against Near - Fault Earthquakes

Abstract

In order to design seismic-resistant buildings, it is necessary to get comprehensive information about their behavior against the forces induced by earthquakes. Seismic design codes have been developed to meet the requirements of a safe and economical structure. According to the structural codes, the designed structures should not be damaged against light or moderate earthquakes so that the members should be had sufficient strength and safety while they should be a ductile complex with a proper structural configuration against severe earthquakes to dissipate the forces caused by ground motions. In the design of steel buildings, the use of moment-resisting frames in combination with braces is a seismic-resistant system. One of these systems is the dual steel moment-resisting frames with zipper braces. In this research, the seismic performance of the moment-resisting frame with the zipper brace system has been studied and its performance has been compared to the performance when the chevron bracing system is used. Three 4-story, 8-story, and 12-story buildings have been selected then they have been modeled by SAP2000 software, and finally, their seismic performances have been evaluated using time history analysis. The structural responses have been compared as comparing the relative displacement of the stories (story drift), the maximum displacement of the roof, and the formation of plastic hinges in the members. The results of the current study have been shown that using a zipper member has been decreased both overall displacement of the structure by about 10 to 30 percent, and also has been reduced the damage index of 4, 8, and 12-story structures by 27, 11, and 12 percent, respectively. The formation of plastic hinges has been directed from horizontal and vertical members toward diagonal members.