大跨预应力混凝土梁式桥后期下挠原因分析

研究目的：大跨混凝土梁式桥后期下挠属很常见的病害，对桥梁具有很大的危害性。迫切需要在造成后期下挠的诸多因素中找出主要因素才能在今后的设计、施工中加以控制，从而达到抑制下挠的目的。 研究方法：从梁式桥的刚度入手阐述挠度的产生机理。进而分析预应力效应、收缩徐变效应、梁体开裂等因素对后期挠度的影响。 研究结论：纵向、竖向预应力有效性的不足造成了后期挠度偏大和梁体开裂。而梁体开裂大大降低了梁体的刚度，致使后期下挠加剧发展。

Analysis of the Cause for Post Down-warping of Large Span Prestressed Concrete Beam Bridge

Research purposes:The post down-warping is a common disaster for large span concrete beam bridge,which can cause serious danger to bridge,so it is urgent to find out the main cause for down-warping for the purposes of prevention of it and finally control of down-warping.Research methods:The explanation is given to the mechanism of causing flexure from beginning with the rigidity of beam bridge,and then the analyses are made for the impacts on post flexure by prestress effects,contracting slow change effects and crack of beam body.Research conclusions:The shortage of availability of longitudinal and vertical stresses cause the post flexure becoming overlarge and crack of beam body and then the crack of beam body cause the rigidity of beam body becoming weak,resulting in development of post down-warping.