城市立交桥牛腿开裂及加固的模型试验

为保障城市立交桥梁的安全运营,以成都市三环路牛龙路立交桥为工程背景,分别进行了主桥和匝道桥牛腿模型开裂及加固的试验研究.通过控制裂缝的区域、形状和大小模拟实桥牛腿开裂,分析引起牛腿开裂的因素;对开裂后的牛腿进行补强预应力筋加固,对比加固前后牛腿的应力,分析补强预应力筋锚下应力,考察该加固方法的有效性.研究表明:引起牛腿开裂的原因有预应力损失过大、重车影响和车辆偏载效应等;补强预应力筋加固切实可行.

Model Test of Corbel Cracking and Reinforcement of Urban Overpass

In order to ensure the safe operation of urban overpasses,model tests of corbel cracking and reinforcement of the main bridge and ramp bridge of Niulong road overpass in Chengdu City were carried out respectively.By controlling the region,shape and size of cracks,corbel cracking of the overpass was simulated,and the factors to cause corbel cracking were analyzed.In addition,a comparative analysis of stresses in the corbel before and after strengthening prestressed reinforcement was made.Stresses under the anchorage of prestressed reinforcement were analyzed to investigate the effect of the reinforcement measure.The research shows that the reasons of corbel cracking are the great loss of prestress,the effect of loaded vehicles and the eccentric loading of vehicles,and the strengthening prestressed reinforcement measure is feasible.