节段预制拼装箱梁桥抗剪性能试验研究

Experimental Study on Shear Resistance of Segmental Prefabricated Assembled Box Girder Bridge

湿接缝纵向拼装的方法在节段预制拼装桥梁中得到广泛应用,但是湿接缝结合面抗剪受力性能研究较为缺乏。以某高速公路20 m装配式预应力混凝土简支箱梁桥为背景,设计了节段预制拼装箱梁桥的抗剪性能足尺模型试验,对桥梁湿接缝节段的抗剪性能进行了研究,建立了试件的有限元计算模型。研究结果表明,现浇接缝和相邻节段预制箱梁的挠度在试验初期变形基本一致;当荷载超过600 kN时,挠度差明显增大;当试验荷载达到1 100 kN时,湿接缝与箱梁混凝土的结合面失去传递荷载的能力,试验模型发生破坏;采用节段预制拼装的箱梁桥,其破坏模式是先结合面开裂后湿接缝混凝土开裂破坏;施加并提高纵向预应力,可以提高拼接箱梁桥结合面开裂后的承载能力。

The method of longitudinal assembly of wet joints is widely used in segmental prefabricated bridges,but the research on the shear performance of the junction surface of wet joints is lacking.Taking a 20 m prefabricated prestressed concrete simply-supported box girder bridge of an expressway as the background,a full-scale model test of the segmental prefabricated box girder bridge was designed,and the shear performance of the wet joint segment of the bridge was investigated by combining finite element calculation and model test.The test shows that the deflection of the cast-in-place joint and the adjacent precast box girder are basically the same at the initial stage of the test.When the load exceeds 600 kN,the deflection difference increases significantly,and when the test load reaches 1100 kN,the joint surface between the wet joint and the box girder concrete loses the ability to transfer the load,and the test model shows failure.The test phenomena and the results of finite element calculation show that the failure mode of the box girder bridge with segmental precast assembly is first the cracking of the joint surface and then the cracking of the wet joint concrete.Applying and increasing the longitudinal prestressing can improve the load-bearing capacity of the segmental prefabricated assembled box girder bridge after the cracking of the junction surface.