钢箱提篮拱桥整桥模态试验研究

EXPERIMENTAL MODAL ANALYSIS OF STEEL BOX BASKET-HANDLE ARCH BRIDGE

随着大型柔性桥梁建设的迅速发展 ,其长期安全运行的健康监测的评估得到很大关注。通过试验模态分析对验证设计、建立结构的动力学模型以及桥梁安全运行状态的评估具有重要意义。拱桥桥面主梁与拱结构耦合振动 ,其模态试验比斜拉桥更加困难。本文通过我国首座建成的云南小湾钢箱提篮拱桥模态试验和竣工试验 ,提出了一种节省试验成本的基于环境激励下桥梁模态试验方法 ,取得了拱桥整体振动的较为正确的模态频率、阻尼及较理想振型 ,与有限元计算基本吻合。

Because of the rapid development of construction of large_scale bridges with flexible girder,more and more attention should be paid to the evaluation and monitoring of bridge's health to insure its safe operation.It is of high significance to verify the design scheme,establish dynamical model and evaluate the security condition by experimental modal analysis.With regard to arch bridges,the modal experiment is much more difficult than that on other types of bridges,such as cable_stayed bridge,etc.In the paper,an innoative modal experimental method for a steel box basket_handle arch bridge is developed based on the ambient vibration induced excitation,which is also validated on the Xiaowan steel box basket_handle arch bridge in Yunnan province,the first erected one of such bridges in China.The experimental modal frequencies,damping ratios and vibration mode shapes are basically in good accordance with the analytical results by FEM.