Experimental study on cyclic behaviour of low yield point steel buckling-restrained braces

Abstract

Low yield point steel is an advanced high-performance material that was deemed to provide reliable cyclic properties based on previous research. This paper presents experimental investigations into low yield point steel buckling-restrained braces (BRBs). Cyclic tests were conducted on nine full-scale specimens made of three grades of low yield point steels in China, including LY100, LY160, and LY225, with the nominal yield strengths of 100 MPa, 160 MPa, and 225 MPa, respectively. The failure modes, hysteresis behaviour, and mechanical indexes were analysed. Results showed that low yield point steel BRBs featured cyclic hardening behaviour with the strain hardening adjustment factor ω of 1.35–2.94, and the LY100 BRB exhibited more significant cyclic hardening (ω = 2.50–2.94) than the other two. Moreover, specimens showed tension–compression asymmetry behaviour with the compression strength adjustment factor β of 1.07–1.51, proving that the maximum compressive loads exceeded 7–51 % of tensile ones. The low yield point steel BRBs could produce stable cyclic behaviour and energy dissipation with the cumulative ductility factor of 491.16–3279.23 upon the acceptance stipulated in American and Chinese codes. Based on the test results, the performance of low yield point steel BRBs was evaluated, and suggestions were proposed for design purposes.