Response evaluation of brb retrofit in RC buildings by considering the composite effect of elastic steel frame

On the retrofit of existing sub-standard RC building with buckling restrained braces (BRBs), the insulation of elastic steel frame around BRBs is effective for restraining the residual deformation and the distribution of damage to whole structure. On this paper, the nonlinear hysteresis of steel frame member including the composite effect observed during the previous cyclic loading test is modelled to investigate its influence on the over-all structural response. Also, when the composite effect is unevenly distributed on each retrofit member, the worst distribution case of the composite effect is searched with genetic algorithm on the aspect of seismic performance is investigated.