先张法预应力空心板桥简支转连续加固方法

先张法预应力空心板桥在服役过程中会出现跨中挠度过大、预应力钢束配筋不足以及预应力损失过大等问题,从而导致桥梁线型不正常、抗弯承载能力不足,再加上先张法钢束不上弯,不能更好参与抗剪,往往会使得支点截面产生抗剪能力不足的现象。要使桥梁同时满足承载能力极限状态和正常使用极限状态的要求,需对其加固。对于多跨简支体系的先张法板桥,较好的方法是采用简支转连续的加固方法。以云南玉溪黑箐桥简支转连续加固为例,分别采用理论计算和荷载试验的方法对该桥进行分析。理论计算的结果表明:体系转换后,跨中弯矩、挠度明显减小,达到了加固效果,提高了桥梁的抗剪、抗弯承载力和抗裂性。荷载试验结果表明:简支转连续加固后,空心板底缘应力平均降低13.2%、挠度平均减小20.7%,结构刚度大幅度提高。

Study on the Method of Simple Support and Continuous Lifting of Hollow Slab Bridge

In the course of service,the pretensioned prestressed hollow slab bridge will have problems such as excessive mid-span deflection,insufficient prestressed steel bundle reinforcement and excessive prestress loss,resulting in abnormal bridge line shape and insufficient bending capacity.In addition,the pre-tensioned steel beam does not bend up,and can not participate in the shearing better,which often causes the fulcrum section to have insufficient shear resistance.To make the bridge meet the requirements of the ultimate capacity state and the normal use limit state,it needs to be reinforced.For the pre-tensioned slab bridge of the multi-span simply supported system,a better method is to use a simple support to continuous reinforcement method.In this paper,the continuous reinforcement of the Yuxi Heiqing Bridge in Yunnan province was taken as an example and the bridge was analyzed by theoretical calculation and load test method.The theoretical calculation results showed that,after the system was converted,the bending moment and deflection in the mid-span were significantly reduced,and the reinforcement effect was achieved,which improved the shear resistance,bending capacity and crack resistance of the bridge.The results of load test showed that,after continuous reinforcement,the stress at the bottom edge of the hollow slab and deflection decreased by 13.2%and 20.7%respectively on average,and the structural stiffness was greatly improved.