轨道交通预应力混凝土U形梁极限承载力试验研究

摘要

In order to study the mechanical behavior of the prestressed concrete U-shaped girder in the urban rail transit,a span of 30 meters of prestressed concrete U-shaped simply supported girder bridge was statically tested. T he strain in concrete and steel bars was measured at the key sections and the relationship between the vertical deflection and the load was studied. T he failure process and mode were analyzed. T he decompression moment of the main girder was 1. 31 times its design moment. T he girder started its plastic stage when loaded to 2. 0 times the design load. T he failure load was 2. 7 times the design load. Distinct transverse strain occurred at the bottom flange during the loading process,indicating a typical behavior of a 3-dimentional plate. T he failure was ductile,suggesting a reasonable structural design and appropriate safety reserve.%为研究城市轨道交通预应力混凝土 U形梁的力学性能，对一座跨度为30 m的预应力混凝土 U 形简支梁桥进行了静载破坏试验。试验中测试了主梁关键截面混凝土和钢筋的应变以及竖向位移与荷载之间的关系，详细分析了梁体破坏过程与破坏特征。研究得到了如下结论：主梁的消压弯矩为1.31倍设计荷载，在加载至2.0倍设计荷载时主梁开始进入塑性阶段，破坏荷载为2.7倍设计荷载；加载过程中底板出现较为明显的横向应变，表明底板具有典型的空间板受力效应；梁体破坏过程表现出明显的延性，表明结构设计合理，具有较强的安全储备。