跨断层独塔斜拉桥的非线性地震响应特性研究

跨越活动断层的桥梁结构面临地震时断层错动的严重威胁.为合理模拟跨断层地震动的滑冲效应脉冲,基于近断层脉冲型地震动的分解-叠加方法,发展了一种可体现场地高频特征的跨断层地震动合成方法.首次采用最大位移与永久位移之比作为波形参数,基于搜集的96条包含永久位移的地震记录,建立了波形参数与脉冲参数之间的联系.结果表明:所建议方...

Nonlinear Seismic Response Characteristics of Fault-crossing Single-tower Cable-stayed Bridge

Bridge structures crossing active faults suffer serious threats from fault dislocations when earthquakes occur.To simulate the fling-step effect pulses of fault-crossing ground motions rationally,a synthesis method considering high-frequency characteristics at the bridge site was developed based on a decompose-synthesis method of near-fault pulse-like ground motions.Maximum displacement against permanent displacement was first used as a wave shape parameter,and its connection with pulse parameters was established based on 96 collected earthquake records containing permanent displacement.The result indicates that the proposed method can accurately simulate actual fault-crossing ground motions.A deep-water single-tower cable-stayed bridge with its approach span crossing the fault was selected as the object,and the influence law of the fault-crossing angle,permanent fault displacement,and maximum fault displacement on the nonlinear dynamic response of the cable-stayed bridge during an earthquake in three directions was studied.The results show that the fault-crossing angle has a significant influence on the earthquake response of the cable-stayed bridge and its approach span.When the fault-crossing angle approaches 90°(60°-105°),the security of the main tower is higher.This is because of the consistency of the main pulse direction with the stronger direction of the tower bottom and the reasonable force distribution of the main tower.Thus,a strong nonlinear biaxial bending condition of the tower bottom is avoided.Meanwhile,the fault-crossing span has a minimum risk of unseating when the fault-crossing angle approaches 90°.With an increase in the permanent fault displacement,the response of the main tower increases slightly,and the relative displacement between the pier and girder increases visibly.The maximum displacement against permanent displacement represents the proportion of the dynamic and pseudo-static parts in the ground motion parallel to the fault.With this parameter increasing,the response of the tower bottom and the relative displacement between the pier and girder grow significantly.In addition,a fault-crossing simply supported span with a small fault-crossing angle could have a larger risk of unseating.