焊钉连接件时变抗剪性能的试验研究

对于无支架施工的长跨连续组合梁，在施工期间进行分阶段浇筑混凝土时，需考虑不同混凝土龄期的组合梁结合面上连接件的早期组合作用。为此，进行了混凝土不同龄期下焊钉连接件的推出试验，分析了焊钉连接件极限抗剪强度、极限滑移、设计抗剪强度和剪切刚度随时间的变化规律，并给出了相应的时变计算公式。研究发现，混凝土龄期小于3 d时推出试件主要为混凝土板劈裂破坏；在不同混凝土龄期时推出试件的剪力-滑移规律基本相同，但抗剪强度和刚度均随混凝土龄期的增长而增大，且早期增长较快，后期较慢，说明组合梁结合面的早期组合效应不能忽略。

Experimental Analysis of Time-dependent Shear Behavior on Stud Connectors

With regard to the long span continuous composite beams, the early composite shear stud strength at the joint surface between the steel girder and concrete slab at different concrete ages should be considered while the concrete slabs are casted by phases in construction stage. In this study, the push-out test of stud shear connectors were conduced at different concrete ages. Meanwhile, the change law of the ultimate shear strength, ultimate slip deformation, design shear strength, and shear stiffness of the stud shear connectors with concrete ages were analyzed, and the corresponding time-dependent calculation equations were presented. The results include that the main failure modes of stud shear connectors are the concrete slab splitting failure before 3-days concrete age. The load-slip laws of stud shear connectors at different concrete ages are basically the same, however, the shear strength and stiffness all increase with the concrete ages prolonging, and the increase degree is faster at early ages, but slower at later ages, which indicates that the early composite shear stud strength at the joint surface of composite beams should not be neglected.