钢筋套筒灌浆对接与搭接接头力学性能对比

为研究套筒灌浆对接和搭接接头力学性能差异,进行了24个对接和12个搭接接头单向拉伸试验,对比研究了接头的破坏形态、承载力、延性、力-位移曲线、套筒应变等.对接接头在加载过程中套筒中部灌浆料出现全截面开裂现象,加载结束发生了灌浆料从套筒中拔出破坏,搭接接头无以上现象.试验结果表明在套筒长度相同时,搭接接头承载力、总伸长率、刚度分别是对接接头的5~7倍、3~5倍、2~3倍,位移延性系数大于对接接头；在锚固长度相同时,搭接接头承载力、位移延性略大于对接接头,两者初始刚度差别不大,而搭接接头中后期刚度高于对接接头.对接接头套筒中部截面纵向受拉,而搭接接头加载前期受拉,后期受压,反映搭接接头对套筒抗拉强度要求较低；对接接头套筒中部截面环向受压,而搭接接头加载前期受压,后期受拉,说明搭接接头套筒中部对灌浆料约束作用大于对接接头.搭接接头力学性能优于对接接头,可运用于预制装配式结构钢筋连接.

Comparison of mechanical properties of reinforcement sleeve grouting butt joint and lap joint

To investigate the difference of mechanical properties between sleeve grouting butt joints and lap joints, 24 butt joints and 12 lap joints were tested under unidirectional tension. The failure modes, bearing loading capacity, ductility, force-displacement curves, and sleeve strain of the joints were compared and studied. During the loading process, the grouting material of the butt joints cracked in full section at the middle of the sleeve, and was pulled out of the sleeve at the end of the loading process, while the lap joint had no such situation. Test results show that the bearing loading capacity, total elongation, and stiffness of lap joint were 5-7 times, 3-5 times, and 2-3 times larger than those of butt joint respectively when the sleeve length was the same, and the displacement ductility coefficient was larger than that of butt joint. When the anchorage length was the same, the bearing capacity and displacement ductility of lap joint were slightly larger than those of butt joint. The initial stiffness difference between the joints was not obvious, but the mid-late stiffness of lap joint was higher than that of butt joint. When the middle section of the butt joint sleeve was longitudinally tensioned, the lap joint was tensioned in the early stage of loading and compressed in the late stage of loading, which reflects the lower requirement of the tensile strength of the lap joint sleeve. When the middle section of the butt joint sleeve was circumferentially compressed, the lap joint was compressed in the early stage of loading and tensioned in the late stage of loading, indicating that the restraint effect of the middle part of lap joint sleeve on the grouting material was greater than that of butt joint. The mechanical property of lap joint is better than that of butt joint, so it can be used to connect reinforcement bars in prefabricated assembly structures.