多跨预应力混凝土桥梁结构动力特性研究

Study on Dynamic Characteristics of a Muti-Span PC Bridge

基于振动理论的桥梁损伤检测方法需要精确提取桥梁的动力参数,动力参数识别是桥梁损伤检测的首要步骤。为了提取5跨预应力混凝土简支梁桥的动力参数,在桥梁上进行了两组振动试验,分别研究了每跨桥梁的动力特征和5跨桥梁的整体振动特性。所有单跨的4阶动力参数将根据智能无线传感器测量结果,应用快速傅立叶变换、半功率带宽法和交叉反应谱法计算得到。同时也讨论了振动传输,激励跨桥梁和非激励跨桥梁之间的关系。研究结果表明:桥墩长度会影响桥梁的自振频率;存在碎石均布荷载的情况下振动可以在所有跨桥梁之间传播;受竖向激励的一跨桥梁主振型为弯曲模态,非激励跨桥梁主振型趋向于扭转模态。研究结果将作为桥梁健康监测技术的基础研究。

Bridge damage detection method based on vibration theory needs to accurately extract the dynamic pa- rameters of the bridge, and dynamic parameter identification is the first step of bridge damage detection. In order to extract the dynamic parameters of 5-span pre-stressed concrete simply supported beam bridge, two groups of vibration tests were carried out. The dynamic characteristics of every single span and the overall vibration charac- teristics of the all spans were studied. 4 dynamic modal parameters of every single span were calculated with peak picking method, half power method and cross spectrum method based on the smart wireless sensor measurement results. At the same time, the vibration transmission, the relation between the excitation span and the no excitation spans were also discussed. Results show that：the length of the pier had effect to the natural frequen- cies ;vibration can spread across all spans with ballast uniformly distributed load;the predominant mode of the span with vertical excitation was bending mode, and the predominant mode of no excitation spans more likely be- have the torsional mode. The research results will be used as the foundation study of the bridge health monitoring technology.