刚构拱桥动力特性敏感性分析

Sensitivity Analysis of Dynamic Characteristics of Rigid Frame Arch Bridge

刚构拱桥由于拱肋和拱肋上的吊杆以及上下平联横撑的存在,使得其受力性能与动力特性异于连续梁桥,因此针对刚构拱桥结构本身参数进行敏感性动力特性分析,建立三维空间有限元模型,采用多重利兹向量分析法,研究拱肋之间横撑型式、桥墩高度以及支座的连接单元特性对桥梁的动力特性的影响。结果表明,随着刚构拱桥拱肋横撑型式的改变,桥梁自振周期基本一致,说明拱肋横撑型式对刚构拱桥动力特性基本没有影响;随着墩高不断增加,桥梁的自振周期也不断延长。结构的刚度随墩高的增加而减小,桥梁的纵向移动和竖向弯曲效应随墩高越高越显著,且墩高对于高阶振型的影响效果较小;支座显著地延长了此桥的自振周期,但是随着阶数的增大,与原模型的周期越接近,说明了支座对于结构高阶振型的影响也较小。

Rigid frame arch bridge is different from continuous beam bridge due to the existence of arch rib and suspension rod on arch rib as well as horizontal crossbracing.Therefore,sensitive dynamic characteristics of rigid frame arch bridge structure parameters are analyzed,three-dimensional finite element model is established,and Multi-Ritz Vector Method is adopted.The effects of the form of the cross bracing between the arch ribs,the height of the pier and the characteristics of the connecting elements of the supports on the dynamic characteristics of the bridge are studied.The results show that the natural vibration period of the bridge is basically the same with the change of the arch rib brace form,which indicates that the arch rib brace form has no effect on the dynamic characteristics of the rigid frame arch bridge.With the increasing of pier height,the natural vibration period of the bridge is also prolonged.The stiffness of the structure decreases with the increase of pier height,the vertical movement and vertical bending effect of the bridge become more significant with the increase of pier height,and the effect of pier height on the high-order mode is small.The support significantly extends the natural vibration period of the bridge,but with the increase of the order,the period is closer to the original model,indicating that the support has less influence on the higher order vibration mode of the structure.