Seismic performance test and practical calculation method of thin-walled square#br#
section steel piers under horizontal bi-directional seismic excitations
Zhuge Hanqing1 Xie Xu1 Li Shuailing1 Wang Jiandong2
1. Zhejiang University, Hangzhou 310058, China;2. Zhejiang University of Technology, Hangzhou 310023, China
Abstract：Local instability of steel plates is one of the typical seismic failures of steel pier structures. However, there is still a lack of structural seismic response analysis methods that can take into account the effect of local instability and be conveniently used in the engineering design. By applying horizontal cyclic load in oblique direction to two thin-walled square-section steel pier specimens, seismic damage form and seismic performance of structures were studied. Based on the modified two-surface steel hysteresis model, a fiber-model calculation method considering the effect of local instability of steel plates of square-section steel piers was established through data fitting of the structural parameter analysis results. The results show that under bi-directional seismic excitations, thin-walled square-section steel pier structures will firstly suffer from local instability of steel plates at the bottom of piers, and ultra-low-cycle fatigue cracking will occur at the weld of the bottom after the load reaches the highest point. Under the combined action of two types of seismic damage, the bearing capacity of the structures drops rapidly. By comparing the analysis results with the test ones, it is shown that if the equivalent hysteresis model is adopted for the fiber elements in the effective damaged zone Ld of structures, the local instability effect of steel plates can be accurately considered. The research results can provide a highprecision practical calculation method for engineering design.
