近断层地震动作用下铅芯橡胶隔震体系的参数优化

Parameter Optimization of LRB Isolation System Subjected to Near-fault Ground Motions

以铅芯橡胶隔震支座耗散的地震能量最大为目标函数,以隔震层最大位移和顶层加速度峰值最小为主要约束条件,对近断层地震动作用下LRB隔震体系的参数进行优化。研究表明,在近断层地震动作用下LRB隔震体系屈服剪力系数的最优取值范围为0.1～0.14,最佳屈服剪力系数随着第二隔震周期的增大而减小,屈服位移较高时最佳屈服剪力系数也较大。屈服前刚度与屈服后刚度比的最优取值范围为16～35,但最优刚度比随屈服位移的减小呈比例增大,刚度比随屈服剪力系数的增大也略有增大。

The objective function selected for optimality is the maximization of seismic energy dissipation of LRB. The main constraint condition selected for optimality are the minimization of both the maximum displacement of isolation layer and the peak top floor acceleration. The parameters of LRB isolation system under near-fault ground motions are optimized. The research indicates that the optimum yield shear coefficient of the LRB is found to be in the range of 0. 10 ～ 0. 14 under near-fault motions. The yield shear coefficient decreases with the increase of second isolation period. The optimum yield shear coefficient of LRB with higher yield displacement is larger than the bearing with low yield displacement. The optimum yield shear stiffness and post-yield stiffness ratio of the LRB is found to be in the range of 16- 35. The optimum stiffness ratio increases proportionally with the decrease of yield displacement. The optimum stiffness ratio increases slightly with the increase of yield shear coefficient.