大跨斜拉桥Rayleigh阻尼系数约束优化解  

Constraint optimal solution of Rayleigh damping coefficients for long-span cable-stayed bridges

作　　者：潘旦光[1] 靳国豪 高莉莉[1] 

机构地区：[1]北京科技大学土木系,北京100083

出　　处：《振动与冲击》2014年第16期34-41,共8页Journal of Vibration and Shock

基　　金：国家自然科学基金(51078032);北京市自然科学基金(8143037)

摘　　要：进行大跨桥梁地震反应分析时以结构位移反应峰值误差为目标函数,建立求解Rayleigh阻尼系数的优化分析方法。考虑基频模态为结构动力反应的最显著贡献模态,以基频模态阻尼比等于精确值为约束条件,形成求解Rayleigh阻尼系数的约束优化方程;以840 m长斜拉桥为例分析Rayleigh阻尼系数随优化计算模态数及参考自由度变化规律。与传统Rayleigh阻尼比较,讨论不同阻尼模型对结构位移、内力计算误差。数值计算结果表明,该方法可有效降低位移、内力计算误差,避免人为选择参考频率所致任意性,适合工程结构计算与分析。For the seismic response analysis of long span bridges,an optimal analysis method was proposed to solve Rayleigh damping coefficients. In the method,the errors of structural displacement peaks were taken as the optimization objective function. Meanwhile,considering that the fundamental-mode contribution is usually significantly larger than others,the constraint condition was described as the equivalence between the modal damping ratio of fundamental mode and the exact value. So,a constraint optimization equation was developed for solving Rayleigh damping coefficients.Then,the effects of the modes number and the referencial degrees of freedom in optimization calculation on the evaluation of Rayleigh damping coefficients were investigated,taking a 840m-long cable-stayed bridge as an example. Comparing with the traditional Rayleigh damping,the errors of structural displacements and internal forces under four kinds of earthquake excitations were discussed. The numerical results show that the proposed method can reduce the calculation errors of displacements and internal forces effectively,and avoid the artificial selection of referencial frequencies,which is suitable for calculation and analysis of engineering structures.

关 键 词：大跨桥梁 地震反应 Rayleigh阻尼 约束优化分析 

分 类 号：TU311.3[建筑科学—结构工程] U442.55[建筑科学—桥梁与隧道工程]