Experimental investigations on seismic behavior and design of bottom vertical boundary elements in multi-story steel plate shear walls

This research investigates the seismic behavior and design method for the bottom-level boundary columns, also called the vertical boundary elements (VBEs), in multi-story steel plate shear walls (SPSWs). This paper firstly introduces the proposed design method for the bottom-level VBE for the case when a frame swaying action causes the VBE to bend in single curvature, as is often seen in mid- and high-rise buildings. Two 12-story (12F) prototype SPSWs were designed using the proposed design method. Two 40%-scale substructural test specimens representing the first 2.5 stories of the 12F SPSW prototype designs were cyclically tested with the Multi-Axial Testing System at the Taiwan National Center for Research on Earthquake Engineering in 2013. The test results confirm the effectiveness of the proposed design method in predicting the yielding of the top end of the bottom VBE. In addition, test results show that the lateral torsional buckling of the bottom VBE could occur after the VBE top end yields, indicating that premature top-end yielding should be prohibited for the bottom VBE before the SPSW develops uniform yielding mechanism under the lateral forces.