佛开高速九江大桥模态测试与分析

Modal Test and Analysis of Jiujiang Bridge in Fokai Highway

对主跨为160 m的预应力砼变截面连续梁桥佛开高速九江大桥进行了理论与实验模态分析,首先介绍了环境激励条件下现场模态测试布置及过程,利用随机子空间法(SSI)进行了桥梁模态参数识别,建立了桥梁有限元模型,并对理论和实验模态分析结果进行了比较和讨论。实验与有限元计算结果在竖向模态频率及振型上总体吻合较好,测试结果可以为有限元模型修正提供依据;模态测试与有限元分析相结合,可以为桥梁长期健康监测和损伤评估提供较可靠的基准模型。

In this paper, experimental and theoretical modal analyses were conducted for Jiujiang bridge in Fokai highway, which is a prestressed reinforced concrete continuous bridge with variable cross-sections and a main span of 160 m. The layout and procedure of modal test was introduced first and the bridge dynamic characteristics were then identified from the test data using stochastic subspace identification （SSI） method. A finite element model was also established for the bridge and the FEM analysis results were compared to the test ones. The results show that the natural frequencies and mode shapes in the vertical direction from the test and FEM analysis are comparable. The test results are helpful for updating the FEM model and the two studies combined together can provide a base model for bridge health monitoring and damage evaluation.