According to a 26-storey benchmark model of concrete-filled steel tubular（CFST）composite frame with buckling restrained brace（BRB）

an optimization program was designed based on mode response spectrum method and genetic algorithm.The optimal design of cross-sectional area of BRB for CFST composite frame was presented by calculating the lateral stiffness ratio of each storey.Moreover

the seismic response during elastic and elastic-plastic stages was analyzed for of the structure designed with varying or fixed lateral stiffness ratios.The results show that the structure designed with varying lateral stiffness ratios can reduce the consumption of 48% of BRB while maintaining earthquake-resistant properties.Under the influence of rarely occurred strong earthquakes

the energy dissipation ratio of the BRB designed with varying lateral stiffness ratio is 54.98%

and the plastic deformation capacity of the BRB can effectively consume earthquake energies

which protects the beams and columns from damage.