Constitutive Model of Low-Yield Point Steel and Its Application in Numerical Simulation of Buckling-Restrained Braces

Abstract

Low yield point (LYP) steel is a kind of excellent material used in seismic structures. To get its constitutive model under cyclic loading, 20 specimens made of LYP steel SLY100 were tested under different loading systems. Monotonic characteristics, hysteretic curves, and failure modes were analyzed. Skeleton curves under cyclic loads were fitted. Parameters of combined hardening model were calibrated and verified. Then the constitutive model was applied in the numerical simulation of BRBs. It was indicated that SLY100 steel exhibited significant cyclic hardening phenomena and possessed distinguished ductility even after being subjected to cyclic loading. The Ramberg-Osgood model fit the skeleton curves well under cyclic loading with strain increasing gradually; good consistency between the stress–strain curves calculated by ABAQUS and test curves demonstrated the accuracy of the hardening parameters proposed. The finite element (FE) model of the buckling-restrained braces (BRBs) with SLY100 steel in which calibrated results were applied could simulate BRBs’ performance well.