Experimental and numerical study of the seismic performance of an all-steel assembled Q195 low-yield buckling-restrained brace

Abstract

A new type of buckling-restrained brace (BRB), namely, an all-steel assembled Q195 low-yield-point buckling-restrained brace (LYBRB), is proposed in this paper. The difference between the LYBRB and a traditional BRB is that Q195 low-yield point steel with an in-line cross-section (which can better absorb seismic energy) of the core material is adopted. A Q235 steel core is used for the comparative analysis. Additionally, to prevent residual stress, water cutting is performed to cut the core plate. A quasi-static low-cycle reciprocating load test is conducted to determine its failure mode, hysteretic response and restoring force model. The seismic behavior of the LYBRB is evaluated according to the following performance indices: the hysteresis curve, skeleton curve, tension and compression nonuniform coefficient, energy dissipation coefficient, equivalent viscous damping ratio, plastic deformation performance, and in-plane and out-of-plane lateral displacements of the external restraining plate of the LYBRB. The failure mode of the LYBRB is tension-controlled; its hysteresis curve shows good symmetry, stability and fullness; and its energy dissipation capacity support is better. Combined with the restoring force model obtained via an experiment, the bilinear kinematic hardening model is adopted to conduct finite element (FE) numerical simulation analysis of the core plate. Comparison with the test results shows that both the failure mode and the hysteretic response are in good agreement. The influence factors (such as the gap-thickness ratio between the core plate and external restraining plate, width-thickness ratio, core material properties and slenderness ratio of the core plate in the weak-axis direction for the LYBRB) are then used to carry out a parametric analysis to provide better insight into the LYBRB.