深水矩形空心桥墩地震响应分析

Seismic Response Analysis of Deep-water Rectangular Hollow Pier

研究目的:我国西南水电工程多,地震多发,铁路、公路等线路工程时有跨越水库。本文以汶川某跨越库区公路桥为例,探讨深水矩形空心桥墩在地震作用下的振动响应规律和其对墩身稳定性的影响,以增进对深水中矩形空心桥墩地震动响应的认识。研究结论:(1)水体减小了墩体自振频率,内域水体对低阶模态频率降低较大,外域水体对高阶模态频率降低较显著;(2)内、外域水体对墩顶位移和加速度影响程度接近,但外域水体比内域水体对墩体内力和应力的动力响应要大;(3)有水域时横隔板对桥墩的自振频率降低很大,对墩顶位移和加速度影响甚微,对墩体内力和应力影响较大,且设置横隔板时墩体在设置处出现了内力和应力的突变,易造成应力集中;(4)本研究成果对于优化深水矩形空心桥墩的抗震措施具有工程价值。

Research purposes： There are many hydropower projects in Southwest China, where has frequent earthquake, sometimes line projects such as railway, highway cross reservoir. Based on a highway bridge across reservoir in Wenchuan area, this paper made a research on vibration response rules of the deep rectangular hollow bridge pier under earthquake action and its impact on the stability of the pier, improved the understanding of deep rectangular hollow bridge pier seismic response. Research conclusions：（ 1 ）Water reduces the pier＇s natural vibration frequency, and increases pier- top＇s displacement and acceleration. At the same time, the internal water to pier＇s low - order modal frequency reduces larger, and the external water to pier＇s high - order modal frequency reduces notable. （2） The internal and external water to affect the pier - top＇s displacement and acceleration is equal. But the dynamic response of external water to the pier＇s internal force and stress is bigger than that of internal water. （3）When there is water, diaphragm can reduce the natural vibration frequency of pier, and has little influence of pier - top ＇s displacement and acceleration; however it has deep effect on pier＇s internal force and stress. And setting diaphragm , pier＇s internal force and stress will mutate at the place of setting diaphragm. This will easily form the concentration of stress. （4） It has important significance and construction value to the optimization of deep -water hollow pier＇s aseismatic measures.