基于虚拟激励法的大跨径连续刚构桥地震作用下力学特征分析

Analysis of Mechanical Characteristics of Long-span Continuous Rigid Frame Bridge Under Earthquake Action Based on Virtual Excitation Method

为探究大跨径连续刚构桥在各维度地震作用下结构受力规律,基于随机振动理论,将虚拟激励法应用至连续刚构桥抗震分析中。并以某(65+120+65)m连续刚构桥为分析对象,选取Clough-Penzien功率谱模型对比分析了各维地震激励下主梁和桥墩力学响应特征。计算结果表明:一维激励下,各方向的激励荷载分别控制各方向的弯矩;纵向+横向二维激励下主梁纵向和横向弯矩与纵向、横向一维激励规律大致相同,均方根结果有小幅增大;在竖向激励下,结构反对称振型被激发,使得主梁和桥墩弯矩值有所降低;结构位移变化规律与弯矩变化规律大致相同。

In order to explore the law of structural forces of long-span continuous rigid frame bridges under various dimensional earthquakes,based on random vibration theory,the virtual excitation method is applied to the seismic analysis of continuous rigid frame bridges.Taking a(65+120+65)m continuous rigid frame bridge as the analysis object,the Clough-Penzien power spectrum model is selected to compare and analyze the mechanical response characteristics of the main girder and bridge piers under various dimensional seismic excitations.The calculation results show that under one-dimensional excitation,the excitation load in each direction controls the bending moment in each direction;the longitudinal and lateral bending moments of the main beam under the longitudinal+lateral two-dimensional excitation are roughly the same as the longitudinal and lateral one-dimensional excitation laws,and the root mean square result is a slight increase;under vertical excitation,the antisymmetric mode of the structure is excited,which reduces the bending moment of the main girder and bridge piers;the change law of structural displacement is roughly the same as that of bending moment.