基于随机车流-桥梁耦合振动的板梁桥铰接缝裂缝扩展分析方法

Analysis Method for Crack Propagation of Joints in Slab Girder Bridges Based on Coupled Vibration of Random Traffic Flow-bridge System

为明确公路空心板梁桥铰接缝在随机车流荷载长期作用下的裂缝扩展情况,提出一种基于随机车流-桥梁耦合振动的铰接缝疲劳裂缝扩展分析方法:首先,基于Monte-Carlo法建立随机车流模拟模型;其次,将随机车流荷载作为外部激励,并结合车桥耦合理论,建立随机车流-桥梁耦合振动分析模型;最后,基于Paris疲劳裂缝扩展模型,开展铰接缝裂缝扩展行为分析。以一座公路空心板梁桥为分析对象,进行缝裂扩展规律探究,结果表明:空心板梁桥铰接缝裂缝在随机车流作用下的扩展形式以下缘混凝土轴拉疲劳开裂为主;实际工程中,应重点关注与行车道中心线较近的铰接缝健康状况,其次应关注距超车道与行车道的总中心线较近的铰接缝状态;铰接缝裂缝的扩展速度随车重、超载车辆数目及初始裂缝高度增加而加快。

To investigate the crack propagation behavior of joints in slab girder bridges under long-term loading of random traffic flow,this study proposes a method for analyzing the fatigue crack propagation behavior of joints in plate girder bridges based on coupled vibration analysis of a random traffic flow-bridge system.Firstly,a random traffic flow simulation model was established based on the Monte Carlo method.Secondly,a method for analyzing coupled vibration between random traffic flow and bridges was established based on the vehicle-bridge coupling theory.Finally,using the Paris fatigue crack propagation model,the fatigue crack propagation behavior of the joints was investigated.The crack propagation law was explored by considering a slab girder bridge on a highway as an example.The results showed that the expansion of cracks in the joints of hollow slab girder bridges under random traffic flow was mainly due to fatigue cracking of the lower concrete under tension.In practical engineering,attention should be paid to the health status of joints closer to the centerlines of overtaking lane and carriageway.The crack propagation rate of the joint increased with the vehicle weight,number of overloaded vehicles,and the initial crack height.