Numerical simulation of the cyclic‐loading behavior of steel chevron‐braced moment‐resisting frames

Abstract

A computational study was conducted to examine the seismic performance of steel moment‐resisting frames (MRFs) provided with chevron concentric braces. Such steel systems are widely used for buildings in Japan. Nonlinear finite‐element‐method models were validated against data and observations from previously tested chevron‐braced MRF specimens. The validated models were used to conduct a parametric study to understand how the cyclic‐loading performance of chevron‐braced MRFs may be affected by the torsional and translational restraint of the beam intersected by braces, the relative strength of the beam with respect to the braces, and the type of bracing connection. The results suggest that the lack of bracing of the beam intersected by braces may not be detrimental to the global hysteretic behavior of the structural system, although out‐of‐plane buckling of the braces can cause severe inelastic lateral‐torsional deformation of the beam. The torsional moment delivered by the braces was evaluated for the unfavorable arrangement where the bracing connections are rigid, and the braces are oriented to buckle out of the plane. A design procedure was examined that can account for the dependency of the energy dissipation mechanism on the cyclic loading history.