锻压式半灌浆套筒结构设计及单向拉伸性能试验

Structure Design and Uniaxial Tensile Performance Test of Forging Semi-Grouting Sleeve

针对装配式预制构件连接部位受力特点、安装控制难点及套筒加工工艺、原材料、成本等问题,基于冷锻压和热处理工艺,设计新型锻压式半灌浆套筒,按照规范要求制作对中连接试件和偏心连接试件,通过单向拉伸试验对接头连接试件极限承载力、残余变形、最大总伸长率等力学参数以及套筒表面应变分布规律等进行研究分析。结果表明:试件破坏均为连接钢筋拉断破坏,各项参数指标均满足JGJ107—2016Ⅰ级连接接头的相关要求;试件破坏荷载-位移曲线与钢筋原材相似,包含弹性阶段、屈服阶段、强化阶段和连接钢筋颈缩断裂阶段,但试件屈服台阶和强化阶段曲线均较钢筋原材长,灌浆接头可靠性更高;套筒对灌浆料具有主动约束作用,在一定程度上增加灌浆锚固段锻压凹槽数量,有助于提高套筒对灌浆料的轴向滑移约束和径向膨胀开裂约束作用。

In view of the stress characteristics of the connection part of the prefabricated components,the installation control difficulties,the sleeve processing process and the cost of raw materials,a new forging semigrouting sleeve was designed based on cold forging pressing and heat treatment processes.In this paper,the alignment connection specimen and the eccentric connection specimen were prepared according to the specifications.Through the unidirectional tensile test,the ultimate bearing capacity,residual deformation,maximum total elongation and other mechanical parameters of the joint connection specimens and the strain distribution law on the sleeve surface were studied and analyzed.The results showed that the failure modes of the specimens were all tensile failures at non-specific locations of the connecting steel bars,and all the parameters satisfied the requirements for the tensile strength of the joint of I grade in JGJ 107—2016.The failure load-displacement curve of the specimen was similar to the original steel bar,and both included the elastic stage,the yield stage,the strengthening stage and the fracture stage.However,both the yield step and the strengthening curve of the specimen were longer than the original steel bar,so the grouting joint was more reliable.The sleeve had an active restraint effect on the grouting material.To a certain extent,increasing the number of forging grooves in the grouting anchoring section was beneficial to improve the axial slip restriction and radial expansion cracking restraint effect of the sleeve on the grouting material.