自攻螺钉与拉铆钉混合连接受剪承载性能试验

Experimental Investigation of the Shear Behavior of the Blind Rivet and Self-tapping Screw Hybrid Connection

为改善自攻螺钉连接的构件在地震作用下易发生拉脱导致结构严重破坏的缺点,提升冷弯薄壁型钢组合墙体抗破坏能力,分析了组合墙体层间连接处的传力机理,针对自攻螺钉的破坏模式,提出拉铆钉与自攻螺钉混合连接。为研究混合连接的抗剪性能,共进行了48组连接接头抗剪性能试验,包含冷弯薄壁型钢结构常用的5种连接板厚度,不同搭接板厚比(变化范围1.0~2.0),包含纯自攻螺钉连接、纯拉铆钉连接及混合连接的连接方式。观察混合连接的破坏模式,自攻螺钉未发现拉脱破坏,其破坏模式主要表现为:板承压破坏与螺钉倾斜组合破坏、铆钉剪断破坏及板承压与铆钉部分剪断组合破坏3种;相较单一连接方式,混合连接荷载–位移曲线表现出更长的塑性阶段;当板厚比大于1.5且组合板厚小于3.0mm,混合连接的承载力及延性较单一连接增长明显;利用现有计算方法对混合连接的承载力进行累加计算,与试验结果对比,计算结果偏保守。研究发现:混合连接能较好地弥补拉铆钉和自攻螺钉受剪过程中的缺陷,有效改善自攻螺钉拉脱破坏,从而提升连接的承载力及延性;板厚和板厚比是影响混合连接破坏模式及承载力的重要因素,与单一连接相比,板厚比越大,承载力提升越大;排布方式对混合连接的力学性能及破坏机理影响有限;在本文试验工况下,结合混合连接的破坏模式,在现有计算方法的基础上,提出改善后的计算方法,其计算结果更合理。

This study proposes a hybrid connection of pull rivets and self-tapping screws to address the defects in components connected by selftapping screws,which are susceptible to pulling and causing severe damage to the structure during seismic activity,and enhance the anti-destruction capability of cold-formed thin-walled steel composite walls activity.This connection aims to mitigate the failure modes of self-tapping screws by analyzing the force transmission mechanism at the interlayer connection of composite walls.In this regard,a total of 48 sets of joint shear performance tests are conducted to evaluate the shear resistance of the hybrid connection.These tests include five common thicknesses of connection sheets in cold-formed thin-walled steel structures and a range of lap sheet thickness ratios from 1.0 to 2.0.The methods of connection tested are self-tapping screw connections,pull rivet connections and hybrid connections.Observations from the tests showed that hybrid connections prevent the pulling and tearing failures typically seen with self-tapping screws.The failure modes observed are predominantly sheet bearing failure,combined screw tilt failure,rivet shear failure,and partial shear combined with sheet bearing failure.Compared to single connection methods,the hybrid connection’load-displacement curve demonstrates a longer plastic phase.When the thickness ratio exceeds 1.5 and the combined sheet thickness is under 3 mm,the load-carrying capacity and ductility of the hybrid connection increase significantly in comparison to the single connections.The calculated bearing capacity of the hybrid connection,using existing calculation methods,was found to be conservative when compared to the actual test results.The findings suggest that the hybrid connection can effectively counteract the weaknesses of blind rivets and selftapping screws under shear stress,improve the resistance to pulling and tearing of self-tapping screws,and thus enhance the bearing capacity and ductility of the connection.Thickness and thickness ratio are key factors that influence the failure mode and bearing capacity of the hybrid connection.Furthermore,as the thickness ratio increases,so does the bearing capacity.The method of arrangement has a minimal impact on the mechanical performance and failure mechanism of hybrid connections.Under the experimental conditions of this study,based on the observed failure mode of the hybrid connection,an improved calculation method is proposed.This new method is based on existing calculation methods but provides more accurate results.