近断层脉冲地震作用下隔震桥梁等延性位移系数谱

Spectra of constant-ductility displacement ratio for seismic isolated bridges subjected to near-fault pulse-like earthquake

为了进一步深入研究近断层脉冲地震作用下隔震桥梁可能因位移过大导致破坏甚至造成落梁灾害的问题,在收集整理108条近断层脉冲波的基础上,研究了适用于隔震桥梁的等延性位移系数谱,其中延性系数取值范围是5～70.采用地震动脉冲周期对结构自振周期进行标准化,并与其他研究进行对比;研究了延性系数、屈服后刚度比等因素对位移系数谱的影响规律,并提出了指标Ω_μ与Ω_α,用以定量研究上述影响.结果表明,周期标准化后,位移系数谱的变异性显著降低;引入指标Ω_μ与Ω_α后可以简化位移系数谱,因简化引入的最大可能误差不超过10%.并据此建立了可供工程应用参考的简化位移系数谱.

The seismic isolated bridges may be badly damaged and even collapse due to excessive displacement when subjected to near-fault pulse-like ground motions.To further investigate this issue,108 near-fault pulse-like records were first collected,and the corresponding spectra of the constant-ductility displacement ratio for the seismic isolated bridges were computed,in which the ductilityμranged from 5 to 70.The natural period T was normalized by the pulse period T p,and the obtained spectra were compared with those of other studies.Besides,the effects ofμand post-to-pre-yield stiffness ratioαon the constant-ductility displacement ratio Cμwere studied,and then indicatorsΩμandΩαwere introduced to quantify the above effects.Results show that the variability of Cμis subsequently reduced by period normalizing.After introducing indicatorsΩμandΩα,the spectra are further simplified,and the possible maximum error resulting from simplification is lower than 10%.Based on the above results,the simplified spectra of the constant-ductility displacement ratio for seismic isolated bridges were developed.