Test and numerical simulation on the hysteretic behavior of a discspring self-centering and buckling-restrained brace system

Abstract

To reduce the residual deformation of buckling-restrained braces (BRBs), a new assembled self-centering brace (SCB), which lets a BRB part and a self-centering (SC) part with pre-compressed disc springs work in parallel, was constructed. Quasi-static tests and numerical simulations were performed to mainly investigate the effects of constructional details and the self-centering ratio (namely, the ratio of the pre-compressed force of the SC part to the compression strength of the BRB part at a specific story drift) on the hysteretic behavior of SCBs. Both tests and simulations showed that, compared with the BRB, the residual deformation of the SCBs with flag-shaped hysteretic curves was greatly reduced, the hysteretic curves were stable, and the simulation results agreed well with the test result before the tension fracture of plate braces. The SC part could provide both restoring forces and additional energy dissipation. Residual deformations decreased with increasing SC ratio and almost disappeared when the SC ratio αsc1/50 (under 2% story drift) was larger than 1.1. Moreover, simulations reveal that the yielding lengths of the plate brace need to be enlarged to improve the low cyclic fatigue behavior and SC effect of the brace. On the whole, the relationship between residual deformation and αsc1/50, from 0.3 to 1.1, is linear. The pre-tension forces of inner and outer pull rods in the SC part can adjust the initial stiffness of SCBs under tension.