Seismic performance of WUF-W connections with weak panel zones satisfying the proposed panel zone strength ratio

Abstract

In modern seismic design, strong column-weak beam (SCWB) conditions are required for steel special moment frames (SMFs) to avoid abrupt column sway mechanism. In addition, panel zones should have sufficient shear strength to prevent excessive panel zone deformation causing brittle connection fracture. Recently, several experimental studies have reported that connections with weak panel zones (WPZ) exhibited excellent seismic behavior. The aim of this study is to evaluate the seismic performance of welded unreinforced flange-welded web (WUF-W) connections with WPZ. Test data of WUF-W connections with WPZ are collected. To supplement the limited test data, nonlinear three-dimensional finite element analyses are conducted. Based on collected and simulated data, parametric studies are conducted to propose a lower bound for the panel zone strength ratio that can guarantee the satisfactory seismic performance of WUF-W connections. In addition, to assess the effect of WPZ on system performance, the seismic collapse performance of four- and 12-story SMFs with WPZ is evaluated and compared with that of corresponding SMFs with strong panel zones (SPZ). SMFs with WPZ satisfying the proposed lower bound of panel zone strength ratio exhibit superior seismic performance to SMFs with SPZ.