钢超薄 UHPC 组合桥面板界面抗剪性能研究∗

摘要

For the composite bridge deck system composed of orthotropic steel deck and ultra-high-per-formance concrete (UHPC)layer with 35 mm UHPC plate and 20 mm wearing layer,the UHPC layer is too thin to use conventional shear connectors.Therefore,an innovative shear connectors using the welded rebar mesh was proposed.Load-slip curve and ultimate bearing capacity were evaluated by push-out test. In the background of a Yangtze River Bridge,the optimal lay out of shear connectors was investigated by segmental model of a bridge deck.The test results showed that the brittle failure of the shear connectors occurred,and the ultimate bearing capacity of the shear connector with the 50 mm welded rebar mesh was 119kN.The slippage of the shear connector with the welded rebar mesh was less than that of the stud un-der the same load ratio.Furthermore,the stress at the bottom of UHPC layer should be considered in the arrangement of the shear connectors.Increased layout density of the shear connectors reduced the trans-versal and longitudinal tensile stress at the bottom of UHPC layer up to 36.3 %.%针对正交异性钢板超薄超高性能混凝土(Ultra High Performance Concrete, UHPC)(厚度为35 mmUHPC板+20 mm磨耗层)组合桥面板中,UHPC 层过薄而无法采用常规抗剪连接件形式的问题,提出一种新型钢筋网局部焊接抗剪连接件.通过推出试验测得了焊接抗剪件的荷载滑移关系曲线和抗剪承载力,以某长江大桥为背景,对焊接抗剪件的布置方式进行了研究.试验结果表明：焊接抗剪件的推出试验破坏过程属于脆性破坏,破坏前界面相对滑移较小,焊缝长度为50 mm的焊接抗剪件极限抗剪承载力为119 kN.与栓钉相比,相同荷载比值下采用焊接抗剪件的界面相对滑移小,焊接抗剪件的抗剪刚度大于栓钉.计算结果表明：钢超薄 UHPC 组合桥面板在布置抗剪件时,需关注 UHPC 层底部受力.加大抗剪连接件布置密度可减小UHPC层底部横、纵桥向拉应力,降幅可达36.3%.