【摘要】 大跨度公铁两用钢桁梁斜拉桥是一种技术复杂的特殊桥梁,为系统地把握该类型桥梁结构在地震作用下的动力响应规律,总结该类桥梁的总体结构特征,统计分析5座公铁两用大桥的结构动力特性值,利用有限元数值仿真方法分析不同结构抗震约束体系的地震响应特点,统计粘滞阻尼器的减震效果并解释效果差异的原因。研究表明:大跨度公铁两用斜拉桥的竖向刚度与公路斜拉桥相比有明显差异,前者的竖弯基频比后者平均高20%左右;在多种结构抗震约束体系中,具有耗能显著特点的液体粘滞阻尼器体系是一种较为理想的结构抗震支承体系;采用粘滞阻尼器后,6座大桥桥塔的弯矩减震率呈现20%左右与60%以上两种不同表现结果,该现象主要与地震动输入的长周期成分取值有关;由于剪力比弯矩的阶次低,导致桥塔剪力比弯矩的减震效果低;粘滞阻尼器对梁端位移的减震效果显著,可达到60%~80%。更多还原

【Abstract】 The long span rail-cum-road steel truss girder cable-stayed bridge is a type of the special bridge of technical complexity.To systematically understand the structural dynamic response laws of such type of the bridges under the action of earthquake,the general structural characteristics of the bridges were summed up and the structural dynamic characteristic values of 5long span rail-cum-road steel truss girder cable-stayed bridges were statistically analyzed.The seismic response characteristics of the different structural seismic restraint systems were analyzed,using the finite element numerical simulation,the damping effect of the fluid viscous dampers was statistically collected and the differences of the damping effect were illustrated.The results of the analysis demonstrate that the vertical stiffness of a long span rail-cum-road steel truss girder cablestayed bridge is significantly different from that of a long span highway steel truss girder cablestayed bridge and the vertical bending base frequency of the former is averagely 20% higher than that of the latter.Among the varied structural seismic restraint systems,the fluid viscous damper system characterized by the significant energy dissipation is an ideal structural seismic resistance support system.After the fluid viscous dampes are used,the moment damping rates of the pylons of the 6cable-stayed bridges exhibit two kinds of the results of about 20% and above 60%.This phenomenon is mainly related to the values of long period components of the ground motion input.Because the orders of the shear are lower than those of the moment,the damping effect of the shear of the pylons is lower than that of the moment.The damping effect of the viscous dampers on the girder end displacement is significant and the effect can reach 60%~80%.更多还原