低周往复荷载下混凝土-灌浆料-混凝土连接节点抗剪性能

Shear performance of concrete-grouting material-concrete connection joint under low cyclic loading

  • 摘要: 聚丙烯(Polypropylene,PP)纤维灌浆料是一种高性能水泥基复合材料,具有高强、阻裂和增韧的特点,在预制构件进行钢筋套筒灌浆连接时,可以充分填补构件单元间的接缝及套筒内的空腔,提高界面的连接性能。在构件连接部位形成的混凝土-灌浆料-混凝土(CGC)连接节点的双界面的抗剪性能是保证结构整体安全性的关键。考虑键槽高度、界面配筋率、轴向压力和灌浆料饱满度,研究了低周往复荷载下CGC连接节点的破坏模式、抗剪承载力、刚度、耗能和延性的变化规律。结果表明:CGC连接节点破坏形态以界面水平贯穿裂缝为主,轴向压力的增加使键槽发展出斜向裂缝的同时,节点呈现“X”型剪切斜裂缝;增大键槽高度和轴向压力,能提高CGC连接节点的抗剪承载力、刚度和耗能,但降低了节点的延性;其中,键槽高度由6 mm提升至12 mm和18 mm,节点抗剪承载力提升11%和43%,刚度提升11%和14%,但延性降低10%和21%;界面配筋率的增大改善了节点的抗震性能,而套筒内灌浆料的缺失使节点抗剪承载力和刚度均有下降。根据CGC连接节点的破坏模式,解析了节点双界面剪应力的组成,基于叠加原理建立了CGC连接节点双界面的抗剪承载力计算公式,计算结果与试验值吻合较好。

     

    Abstract: Polypropylene (PP) fiber grouting material is a high-performance cementitious composite material with high strength, crack-resistant and toughened characteristics, which can fully fill the gap between the component units and the cavity in the sleeve when prefabricated components are connected by grouted sleeve, and improve the interfacial connection performance. The shear performance of the double interface of concrete-grouting material-concrete (CGC) connection joint formed at the connection parts of components is the key to ensure the safety of the integral structure. Taking the keyway height, interfacial reinforcement ratio, axial compression ratio and grouting material fullness into consideration, the failure pattern, shear capacity, stiffness, energy dissipation and ductility of CGC connection joint under low cyclic loading were investigated. The results show that the failure pattern of CGC connection joint is dominated by horizontal penetration cracks at the interface, and the increase of axial pressure makes the keyway develop diagonal cracks while the joint shows “X”-type shear diagonal cracks; increasing the height of keyway and the axial pressure can improve the shear capacity, stiffness, and energy dissipation of the CGC connection joint, but reduces the ductility of the joint; among them, the increase of keyway height from 6 mm to 12 mm and 18 mm makes the shear capacity improve by 11% and 43%, makes the stiffness improve by 11% and 14%, but makes the ductility decrease by 10% and 21%; the increase of interfacial reinforcement ratio improves the seismic performance of the joint, while the lack of grouting material in the sleeve decreases the shear capacity and stiffness of the joint. According to the failure pattern of the CGC connection joint, the composition of the shear stress at double interface of the joint was analyzed, and the shear capacity calculation formula for the double interface of the CGC connection joint was established based on the superposition principle. tThe calculated values match well with the experimental values.

     

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