设置多级屈服耗能BRB的桥梁排架墩等能量设计方法OACSTPCD

Traditional buckling-restrained brace(BRB)is widely used for damage control of bridge bents.However,it is difficult to effectively control peak displacement and residual displacement of the system under strong earthquakes due to its low post-yield stiffness and small deforma-tion capacity.Therefore,two kinds of material with different yield points were used to replace the single material in the core deformation section of the traditional BRB,so that its overall mechanical properties are multi-linear with staged yield,forming a multistage buckling-restrained brace(MSBRB).MSBRB was used as a fuse to improve the seismic performance of bridge bents.With an equivalent energy-based design procedure,taking the capacity curve of the bridge bent with MSBRB as the design objective,considering the plastic deformation mechanism and capacity curve of the system under gradually increasing seismic dynamic load,a three-stage seismic design process has been developed based on code for seismic design of highway bridges in China.Finally,based on a design example,the feasibility and accuracy of the design procedure were valid-ated with nonlinear time history analyses.The results showed that the design procedure could well predict the performance state of a bridge bent with MSBRB under different seismic levels.The maximum error between the design value and the simulation value was less than 6%,which could achieve the design objectives of different seismic levels.It was also found that after adding MSBRB,the displacement of the bridge bents was significantly reduced.Under earthquake action E2,the bridge bents can maintain an elastic state,and under more severe earthquake levels,the damage of the bent pier can also be effectively controlled.It shows that MSBRB can effectively improve the seismic performance of bridge bents and control the damage of bridge bents.