深水高墩桥梁地震响应计算分析

Calculation and analysis of seismic response of deep water submerged high pier bridge

水库蓄水后,库区内的高墩桥梁淹没深度较大,为研究深水高墩桥梁抗震性能,以西藏扎拉水电站库区某公路桥为研究对象,采用有限元方法计算线弹性E1和E2地震作用下的桥梁动力特性、桥墩墩顶位移、墩底弯矩、剪力并基于动水附加质量理论计算了地震力。结果表明:考虑动水压力作用后,桥梁结构自振频率减小,桥墩内力和位移值均明显增大。考虑深水高墩动水压力影响后桥墩地震响应虽显著增大,但响应值随着主墩淹没深度变化均呈现出非线性变化。对于深水高墩桥梁,考虑动水附加质量后计算出的纵向、横向地震力是未考虑工况下的2.0,1.2倍。研究成果可为山区深水高墩桥梁设计提供参考。

After reservoir storage,the high pier bridge of submerged depth is larger.In order to study the seismic performance of deep water high pier bridges,a highway bridge in the reservoir area of Xizang Zhala Hydropower Sta-tion was taken as the research object.Finite element method was used to calculate the bridge dynamic characteris-tics,pier top displacement,pier bottom bending moment and shear force under the linear elasticity E1 and E2 earth-quake.The results showed that after considering the hydrodynamic pressure,the natural vibration frequency of the bridge structure decreased,and the internal force and displacement of the bridge pier increased obviously.Although the seismic response of the bridge pier increased significantly after considering the influence of the dynamic water pressure of the high pier in deep water,the response values showed nonlinear changes with the change of the sub-merged depth of the main pier.For the deep water bridge with high piers,the longitudinal and lateral seismic forces after considering the hydrodynamic additional mass were 2.0 times and 1.2 times of those without considering the working condition.The research results can provide a reference for the design of deep mountain high pier bridges in mountainous areas.