Seismic Performance of RC Frames Equipped with Zipper Braces Subjected to the Near-field and Far-field Earthquakes

Subject Areas : Analysis of Structure and Earthquake

Seyyed Ramin Abtahi ¹ , Babak Behforouz ²

1 - Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
2 - Department of Civil Engineering, Dehaghan Branch, Islamic Azad University, Dehaghan, Iran

Received: 2021-09-28 Accepted : 2021-12-19 Published : 2021-11-22

Keywords: Time History Analysis, near-fault earthquake, Chevron brace, Zipper element, Soft story,

Abstract :

In recent years, near-fault earthquakes have received more attention due to their variable frequency nature, pulsing motion, and causing incremental damage. On the other hand, due to the abundance of concrete structures in Iran, more than any other structures, they are at risk of damages caused by near-fault earthquakes. This issue clearly indicates the necessity of using new lateral bracing systems in RC structures. One of the lateral bracing systems is the combination of Chevron braces with zipper elements. Owing to this issue, the main purpose of this study is to investigate the seismic performance of RC frames equipped with zipper braced elements under near-fault earthquakes. Therefore, seven far-fault and seven near-fault earthquake records and three RC frames of 3, 6, and 9 floors with and without considering zipper elements were selected. Then, RC frames were designed using linear static analysis, after which all frames were analyzed by dynamic nonlinear time history analysis. After performing the analysis, the results such as total displacement, relative displacement, story shear, and plastic hinge formation were compared. The results of this study present that the zip-shaped elements have significantly succeeded in transferring asymmetric loads of the lower story braces to the upper stories and have prevented the creation of a soft story in the first height level of the structure. Finally, the comparison of the results ehibits the significant effect of the distance from the fault on the overall and relative deformations of the structures with increasing the height of the stories