超高性能混凝土拼缝连接全预制装配楼板的拉伸和剪切性能研究

Research on Tensile and Shear Performance of Fully-Prefabricated Slabs with UHPC Split-Joints

超高性能混凝土(UHPC)作为一种高强度、高耐久的水泥基复合材料,可以实现传统混凝土材料难以完成的新型高效全装配楼盖结构。预制板间UHPC连接拼缝的性能直接关系楼盖结构整体受力性能,其核心因素是剪力和拉力的传递机理和受力性能。为明确UHPC拼缝的力学性能,分别进行了4个抗拉试验、7个抗剪试验,研究钢筋搭接长度、抗剪槽构造对拼缝受力性能的影响,分析不同参数下试件的裂缝开展、破坏形态、应变发展规律和荷载-位移曲线。研究结果表明:钢筋搭接长度为12倍直径时,拼缝处纵向受力钢筋抗拉强度、抗剪强度能够充分发挥;抗剪槽构造可以显著提高拼缝的抗剪能力,钢筋搭接长度为8倍直径且配置抗剪槽时可以保证拼缝的抗剪能力大于预制板本体。

Ultra high performance concrete(UHPC)is a kind of cementitious composite material with high strength and durability,and can achieve a new type of fully-prefabricated floor structure with high construction efficiency that is difficult to construct with traditional concrete materials.The performance of the UHPC joint between prefabricated slabs is directly related to the overall performance of floor,and its critical issues are the transmission mechanism and mechanical properties of shear and tensile forces.In order to clarify the mechanical properties of UHPC joints,four tensile tests and seven shear tests were conducted to explore the effects of rebar lap length and shear groove construction on the mechanical properties of the joint,and to analyze the crack development,damage pattern,strain development law and load-displacement curve of the specimens with different parameters.The research results showed that when the lap length of rebars was 12 times diameter,the tensile strength and shear strength of longitudinal rebars in the joint could be fully developed.In addition,the shear groove could significantly improve the shear capacity of the joint,and the shear resistance of the joint could exceed that of the prefabricated slab with shear groove configuration and 8 rebar lap length of 8 times diameter.