服役预应力混凝土空心板梁抗剪承载性能

Shear bearing capacity of existing prestressed concrete hollow slab girder

为分析服役多年的预应力混凝土空心板梁的实际抗剪承载能力及破坏模式,开展了先张法预应力混凝土空心板梁的试验研究和数值模拟.首先对某高速公路拆除的13 m空心板梁进行两点对称加载的破坏试验,然后利用有限元软件ABAQUS对加载全过程进行精细化数值模拟,分析了空心板梁的预应力损失以及后浇层、铰缝与预制梁间的黏结滑移行为对抗剪承载性能的影响.结果表明:服役近20 a的空心板梁抗剪承载力仍能满足规范的抗剪设计要求,并具有较好的延性,但安全富余量仅为6%;后浇层及铰缝对空心板梁抗剪承载力贡献达15%以上,但其与预制梁间的黏结滑移行为对抗剪承载力的影响较小;预应力损失虽会加快空心板梁的裂缝开展进程,但对抗剪极限承载力影响较小.

In order to study the actual shear bearing capacity and failure mode of prestressed concrete(PC)hollow slab girder in service for many years,a test and numerical simulation of a pretensioned PC hollow slab girder were carried out.Firstly,a destructive test on a 13 m hollow slab girder demolished from an expressway was carried out under two-point symmetrical loading.Then,the whole loading process of the test girder was numerically simulated refinedly with the finite element analysis soft ABAQUS.The influence of the prestressing loss and the bond-slip behaviors between the postcast concrete layer,hinged joints and the precast girder on the shear bearing capacity of the girder was analyzed.The results show that the shear bearing capacity of the hollow slab girder which have been in service for about 20 years can still meet the design requirements of code and has good ductility,but the safety margin is only 6%.The contribution of the postcast concrete layer and hinged joints to the shear bearing capacity of the hollow slab girder is more than 15%,while that of the bond-slip between them and the precast girder is negligible.The prestressing loss of the PC hollow slab girder can accelerate the girder cracking,but the influence on the ultimate shear bearing capacity of the girder is small.