DEVELOPMENT OF A FINITE ELEMENT MODEL FOR A BUCKLING RESTRAINED BRACE

Buckling Restrained Braces (BRBs) have been used for more than 30 years as structural fuse elements due to their enhanced features when compared to conventional braces: no buckling in compression, stable and quasi-symmetric cyclic response, capacity to dissipate a large amount of energy. To achieve these performances, BRBs are composed of a steel core with variable crosssection that undergoes plastic deformations, and a buckling restraining mechanism that restrains the lateral displacements of the core, thus allowing it to achieve higher buckling modes in compression. The two components are decoupled by an unbonding interface which can be either a material layer, or a small gap. The use of BRBs in Romania is regulated by the seismic design code P100-1/2013, which requires experimental qualification. To overcome this problem, a set of typical BRBs with capacities corresponding to typical steel multi-storey buildings in Romania were tested and qualified at CEMSIG Laboratory. This paper presents the development of a numerical model for the tested BRBs in Abaqus software by using the Finite Element Method (FEM). The calibration of the material model, geometrical nonlinearities, and contact law based on experimental data are presented in detail.