基于超高强灌浆料的高强钢筋套筒灌浆连接力学性能试验研究

Experimental study on mechanical properties of high strength rebar grouted sleeve connection with ultra⁃high strength grouting material

套筒灌浆连接是装配式混凝土结构钢筋连接的主要方式,且采用500MPa级高强钢筋可有效提高连接及构件的承载力和经济性等。本文设计12个考虑锚固长度、灌浆料强度和钢筋强度等参数的接头试件,并进行单向拉伸试验研究,得到连接的破坏模式、应变分布和工作机理等。结果表明:接头主要发生钢筋颈缩破坏,荷载-位移曲线包括线性增长阶段、屈服阶段、强化阶段和颈缩破坏阶段;采用120MPa级超高强灌浆料的试件接头均满足残余变形要求,钢筋、套筒轴向、套筒环向应变和套筒中部约束作用随钢筋锚固长度的增大而减小,套筒和钢筋受力更为均匀。对采用85MPa和120MPa级灌浆料的500MPa级高强钢筋套筒灌浆连接,锚固长度建议值分别为10d和8d。最后,基于理论分析可明确高强钢筋套筒灌浆连接中套筒与灌浆料的粘结力、钢筋与灌浆料的粘结力和钢筋受拉承载力,并得到连接的破坏模式。

The grouted sleeve connection is the mainstream of rebar splicing in the precast concrete structures,and the precast component with 500MPa high strength rebar can effectively improve the bearing capacity and economy of connections and canponents.Twelve grouted sleeve connection specimens with the effect of anchorage length,grouting material strength and rebar strength are designed and analyzed by uniaxial tensile loading test,so the failure modes,strain distribution and working mechanism of the specimens are observed and obtained.The results show that the connection mainly occurs steel bar necking failure,and the load⁃displacement curve mainly contains linear growth stage,yield stage,strengthening stage and necking failure stage.The grouted sleeve connection with 120MPa ultra⁃high strength grouting material can all satisfy the requirement of residual deformation.The rebar and sleeve axial strain,sleeve hoop strain and constraining effect in the middle of sleeve are gradually decreasing with the increase of anchorage length,and the rebar and sleeve are uniformly stressed.For 500MPa rebar grouted sleeve connection with 85MPa and 120MPa grouting materials,the recommended anchorage lengths of 10d and 8d respectively.Finally,the bonding force between sleeve and grouting material,the bonding force between rebar and grouting material,and the tensile bearing force of rebar in the high strength rebar grouted sleeve connection can be accurately calculated by the theoretical analysis,and the failure mode of the connection can also be predicted.