墩高不对称大跨连续刚构桥模态分析与测试

Modal Analysis and Test of Continuous Rigid Frame Bridge with Height-asymmetric Pier

连续刚构桥在跨越山区河流、深谷等各种复杂的地质环境时,常出现需要将桥墩或者跨度设计成不对称的情况,这样就使得其受力特性异于常规桥梁。以某墩高不对称三跨连续刚构桥为工程实例,基于Midas Civil桥梁专用有限元分析软件计算该桥的自振特性,分析了墩高变化对自振特性的影响。探讨了该桥各跨跨中及墩顶支点截面冲击效应与各阶模态振型的关系,介绍了基于环境激励法的模态测试过程,并将模态测试结果与理论结果进行对比,得出一些较为重要的结论,为同类桥梁的检测提供参考。

As the piers and spans of continuous rigid frame bridge has been often necessary to be designed into asymmetry when being across rivers and valleys in the mountains and other complicated geologic environmental conditions,which makes their stress features being different from the ordinary bridges. Taking a typical three-span prestressed concrete rigid frame bridge with asymmetry pier as an example,in this paper,the free vibration characteristics of the bridge has been calculated by the special bridge finite element analysis software Midas Civil. The influence of the change of pier height on the natural vibration has been analyzed and the influence of the cross section of the middle span of the bridge and the top of the pier and the mode shapes of the bridge have been briefly discussed. By Ambient Excitation Method,the testing system and testing process of structural model test have been introduced. Some important conclusions have been drawn as the Modal Testing results have been compared with the theoretical results,which could provide references for similar bridge detection.