UHPC键齿+螺栓连接接缝梁抗弯性能试验研究

Experimental Study on Flexural Performance of UHPC Joint Beams with Tooth Block and Bolted Connection

为了研究预制UHPC键齿+螺栓连接接缝梁的抗弯性能,进行了6根UHPC键齿+螺栓连接接缝梁(简称接缝梁)和2根UHPC整体梁的弯曲试验,探讨梁底配筋、接缝设置钢垫板及涂抹环氧树脂胶等因素对UHPC接缝梁的破坏形式、抗弯承载力、跨中挠度、连接钢板上下缘应变和接缝相对纵向位移的影响;采用有限元软件ANSYS分析了长期压应力作用下UHPC徐变对螺栓预紧力的影响.试验及分析结果表明:UHPC接缝梁在梁底配筋不同的情况下存在接缝梁刚度突变区梁体受弯破坏和键齿楔形破坏引起的接缝破坏2种破坏模式,接缝表面涂抹环氧树脂胶对接缝梁的抗弯性能影响小,接缝两侧设置钢垫板可提高接缝的抗弯承载力,减小接缝梁的跨中挠度和接缝的上、下缘相对纵向位移,且对连接钢板的受弯变形也有一定的改善作用.长期压应力作用引起的UHPC徐变会导致螺栓预紧力下降,下降幅度可达24.7%.

To investigate the flexural performance of precast UHPC joint beams with tooth block and bolted connection,flexural test was performed on six UHPC joint beams with tooth block and bolted connection(joint beams for short)and two UHPC beams without joints. The effects of bottom-longitudinal reinforcement, steel subplate, and epoxy glue setting on joint on the failure mode, flexural strength, mid-span deflection, top-bottom-side strain of connecting steel plate and joint top-bottom-side longitudinal relative displacement of these joint beams were discussed. The effect of UHPC creep under long-time compressive stress on the pre-tightening force of bolt was analyzed by finite element software ANSYS. The results show two failure modes of UHPC joint beams with different reinforcement ratio of bottom-longitudinal reinforcement, one of which is flexural rupture of UHPC section in the region where flexural rigidity is changed, and the other is joint failure caused by wedge-shaped failure of tooth block. The effect of joint-painted epoxy glue on the flexural behavior of joint beams is negligible, and steel subplate setting on the side of joint can not only increase the flexural strength of joint and flexural performance of connecting plate, but also reduce the mid-span deflection of joint beams and joint top-bottom-side longitudinal relative displacement. The UHPC creep under long-time compressive stress can reduce the pre-tightening force of bolt by 24.7%.