预应力混凝土弯桥的极限承载力及其分析

Analysis of Ultimate Loading Capacity of the Prestressed Concrete Curved Bridge

针对传统的平面线弹性理论无法客观分析预应力混凝土桥梁中预应力效应和极限承载力的问题,采用三维实体退化单元模拟混凝土,用荷载等效移置模拟预应力,同时引入材料非线性,对一座典型的曲线梁桥的极限承载力和影响参数进行了分析研究。结果表明,提高结构预应力度,结构的开裂荷载将有所提高,但结构的延性显著降低,极限位移有所减小;采用部分预应力混凝土,结构开裂荷载有所下降,但结构的延性有所增加,对提高抗震性能有利;布置腹板束的弯桥极限承载力要好于仅布置平板预应力束的弯桥。

As conventional plane linear elastic theories cannot objectively analyze the prestressing effect and ultimate loading capacity of the prestressed concrete bridge, the ultimate loading capacity and factors of impact of a typical curve girder bridge are studied with the degenerated 3D solid element to simulate the concrete and the equivalent load displacement to simulate the prestressing force, the material introduced being non-linear. The following results are shown: (1) the greater the prestressing force is, the higher the structural cracking loading will be, but the structural ductility is lowered, and the ultimate displacement is reduced a little; (2) if partial prestressed concrete is used, the structural cracking loading is lowered a little, but the structural ductility is raised, which will have higher anti-seismic performance; (3) the curved bridge with the tendoned web will have greater ultimate loading capacity than the one with the tendoned slab only.