大跨径PC连续箱梁桥体外束加固设计

Design of External Beam Reinforcement for Long-span PC Continuous Box Beam Bridge

徐州某京杭运河大桥主桥上部结构为变截面PC连续箱梁桥。由于桥梁周边港口码头较多,车辆超载现象比较严重,在经过六年多的运营后,连续梁主跨跨中底板出现横向裂缝和腹板斜向裂缝等病害,且裂缝呈不断发展趋势,需要采取加固措施。设计提出采用增设体外预应力束的方法进行加固,并对加固后的桥梁进行空间仿真分析。在加固并运营两年之后,未再出现新的病害,说明本次加固有效地提高了老桥的承载能力、压应力储备及安全系数,效果良好,可为同类型桥梁加固提供参考。

The main structure of a bridge on Beijing-Hangzhou Canal in Xuzhou is a variable cross-section PC continuous box beam bridge. Owing to more port wharfs around the bridge, the overload phenomenon of vehicles is more seriously. There are the diseases of transverse crack on the bedplate and the inclined crack on the web in the middle of the main span of continuous beam after the bridge is operated for more than six years. And the cracks present the continuous development trend. The reinforcement measures are required to take. The article puts forward the method to add the external pre-stressing beam for reinforcement, and carries out the space simulation analysis on the bridge. The new diseases do not occur after the reinforcement and operation for two years. The result shows that this time of reinforcement effectively improves the carrying capacity, pressure stress reserve and safety factors of the old bridge with the good effects, which can be referred for the reinforcement of the similar bridges.