Evaluation of the Ductility of Steel Buildings under Non-uniform Settlement

Document Type : Original Article

Authors

Department of Civil, Water & Environmental Engineering, Shahid Beheshti University, Tehran, Iran.

Abstract

Non-uniform settlements beyond allowable limits in structures, is one of the common items that reduces the seismic ductility of the structure. The aim of this study is to investigate the seismic performance of structures under non-uniform settlement and its effect on ductility of the structure. In this research, six models of steel moment frames with different heights and spans are considered. They have evaluated under seismic condition after applying non-uniform settlements in three cases of single column settlement, double column settlement, and real profile of settlement. The results show that non-uniform settlement reduces the ductility of the structure, however it has no effect on ultimate capacity beyond target displacement. Also, considering both direction of seismic motion, the stiffness of the structure can be reduced in one direction and the structure will become unsymmetric. This is more sensitive to number of stories and spans. Additionally, investigations indicate that the condition of the plastic hinges in the structure becomes generally more critical in the presence of settlement. The condition of the plastic hinges in single and double column settlement scenarios are more critical than the real settlement profile, which is attributed to the presence of rigid body rotation of the structure. Furthermore, the results show that in buildings under settlement, the response of the structure to the pushover analysis is completely different in forward and backward directions.

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Main Subjects


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