Experimental testing of aluminum‐core buckling restrained knee braced Truss moment frames for earthquake resistance

Abstract

Application of Buckling Restrained Braces (BRBs) with Truss Moment Frames (TMFs) results in a robust seismic force‐resisting system, herein referred to as Buckling Restrained Knee Braced Truss Moment Frame (BRKB‐TMF), which utilizes the advantages of both BRBs and TMFs. Although steel is commonly used to make the core of BRBs, previous studies have demonstrated the efficacy of annealed aluminum as a preferred core material because of its high ductility and high over‐strength. However, the deformation compatibility of the truss members with the aluminum‐core BRB in BRKB‐TMFs at high drifts is not well studied in the literature. Hence, an experimental study is performed on a scaled sub‐assemblage of a BRKB‐TMF frame designed using the Performance‐Based Plastic Design method. Cyclic tests are performed on 1:3 scale models of aluminum‐core BRB and BRKB‐TMF to evaluate their performance at drifts corresponding to Maximum Considered Earthquake intensity. Also, to further compare the performance of steel and aluminum as suitable BRB core materials, cyclic tests are performed on BRBs with steel and aluminum cores designed using a consistent criterion. The experiments demonstrated the superior performance of aluminum core BRB over steel core BRB. The experimental studies on the BRKB‐TMF concluded that per the design intent, the BRB acted like a fuse for the frame by restricting all the inelastic deformations to itself and the study frame could successfully meet the target drift criteria.

Experimental tests and numerical simulations of miniature buckling-restrained braces using iron-shape memory alloy bar

“…Towards different purposes, the community explored the utilization of various metallic materials as the core element. For example, aluminum bar was used in lieu of steel bar to address the corrosion problem [10] and mild steel was used to improve the ductility capacity and fatigue life [11]. Through exploring the superelastic nature of NiTi shape memory alloy (SMA) [12][13][14], the community proposed the NiTi-based BRB dampers and experimentally confirmed the excellent capacity of recovering large nonlinear deformation [15], derived the analytical equations of the buckling mode [16], conducted seismic performance evaluation [17] and established the seismic design method [18].…”