考虑基础-墩-梁的大跨度连续刚构竖向振动特性分析

Analysis of vertical vibration characteristics of long span continuous rigid frame bridge considering foundation-pier-beam

以某大跨度连续刚构桥为背景,采用有限元分析软件Midas/Civil,建立了不考虑基础作用和考虑基础作用两种整体计算模型,对比分析了基础(桩土效应)对大跨度连续刚构桥竖向振动特性的影响,并通过改变两种模型的桥墩设计参数,定量地分析了在对大跨度连续刚构桥竖向振动特性分析时桥墩对基础的考虑与否的影响规律。计算结果表明,考虑基础作用会使结构的整体刚度降低,竖向自振频率减小,且对全桥竖向振型有一定的影响;随着墩高的增加,连续刚构桥的竖向基频不断减小,基础的作用越小;当墩高大于30m时,基础对连续刚构桥竖向振动特性的影响较小,在对大跨度连续刚构桥进行竖向振动特性分析时可不考虑基础的作用;而当墩高小于30m时,基础的影响较大,应该考虑基础的作用;随着桥墩截面尺寸的加大,连续刚构桥的竖向基频会增大,且相对于墩高的改变,截面尺寸的变化对连续刚构桥进行竖向振动特性分析时基础的考虑与否影响不大。

Based on a long span continuous rigid frame bridge,the finite element analysis software midas/civil is used to set up the two models with and without the consideration of the function of the foundation.Analyzed the foundation of piles and soil influence on vertical vibration characteristics of the large span continuous rigid frame bridge are analyzed.By changing the two kinds of quantitative analysis of the bridge pier design parameters in the model when analyzing the vertical vibration characteristics of long-span continuous rigid frame bridge piers on the influence law of basic consideration or not.The calculation results show that：considering the basic role will reduce the whole stiffness of the structure,natural frequency of vertical vibration is reduced,and the vibration mode of the whole bridge has a certain influence.With the increase of height of pier,the vertical fundamental frequency of the continuous rigid frame bridge is decreased,and the smaller the foundation.When theheight of pier is higher than 30 m,the foundation has little effect on the vertical vibration characteristics of continuous rigid frame bridge.In the analysis of vertical vibration characteristics of long span continuous rigid frame bridge,the foundation is not considered.But when the height of pier is less than 30 m,the foundation has a greater impact,which should be considered in the role of the foundation.As the pier cross-section size increase,the vertical fundamental frequency of long span continuous rigid frame will increase,and the change of high relative to the pier,the change of the section size has little effect on the basis of the analysis of the vertical vibration characteristics of the continuous rigid frame bridge.