装配式混凝土U型钢筋环扣连接技术应用研究

研发了一种装配式混凝土U型钢筋环扣连接技术,对采用4种不同连接方式的试件进行拟静力试验,观察试验现象及破坏形态,分析各种连接的刚度、延性、滞回性能、耗能能力等。结果表明:U型环扣连接节点的承载力较现浇节点有很大程度提高,且连接部位破坏时钢筋未达到屈服,尚有较大优化空间; 采用90°弯锚连接节点的搭接钢筋在往复荷载作用下的承载力等同于现浇节点,在延性、刚度退化、耗能能力等方面比现浇节点和U型环扣搭接方式差一些,未能在混凝土中实现有效锚固,混凝土压碎时搭接钢筋未屈服; 采用U型环扣搭接方式虽然在延性方面较现浇节点差,但是承载力和刚度退化方面表现均优于现浇节点; U型环扣连接方式的试件存在钢筋排布密集的问题,混凝土对钢筋的握裹能力较弱,搭接区域的混凝土较早损伤破坏; 对比一次性搭接方式,U型环扣分批搭接方式对混凝土的局部损伤更小,连接的延性和耗能能力更优; 采用分批搭接方式的构件受力钢筋在搭接处为受拉屈服,滞回环饱满,受力状态良好,是提高U型环扣连接的有效措施之一。

Application Research on Prefabricated Concrete U-shaped Reinforcement Buckle Connection Technology

A prefabricated concrete U-shaped reinforcement buckle connection technology was developed, and the pseudo-static tests on specimens that adopted 4 different connection methods were conducted. The test phenomena and failure modes were observed, and the stiffness, ductility, and hysteresis behavior, energy consumption of various connections were analyzed. The results show that the bearing capacity of the U-shaped buckle connection node is much higher than that of the cast-in-place node, and the steel bar does not reach yield when the connection part fails, and there is still a large room for optimization. The overlapped steel bar of the 90° bend anchor connection node is equivalent to cast-in-place joints in terms of bearing capacity under the reciprocating load, and it is inferior to cast-in-place joint and U-shaped buckle connection in terms of ductility, stiffness, and energy dissipation capacity. It has not achieved effective anchorage in concrete, when the concrete is crushed, the overlapped steel bars are not yielded. Although the U-shaped buckle connection node is inferior to the cast-in-place joint in terms of ductility, it is better than the in-situ joint in terms of bearing capacity and stiffness degradation. The specimens that adopted U-shaped buckle connection have the problem of densely arranged steel bars, so the ability of concrete to hold the steel bars is weak, and the concrete in the overlap area is damaged and destroyed earlier. Compared with the U-shaped buckle one-time overlap method, the U-shaped buckle batch overlap method has less local damage to the concrete, and the ductility and energy dissipation capacity of the connection are better. The stressed steel bar of the component that adopts the batch overlap method is tensile yielded at the overlap joint, the hysteretic loop is full, and the force state is good. Therefore, batch overlap is one of the effective measures to improve the U-shaped buckle connection.