螺栓连接的H型钢-竹集成材组合结构连接件推出试验

Push-out test on bolt connectors of H-section steel-laminated bamboo lumber composite structure

将H型钢翼缘与侧压竹集成材通过螺栓连接形成一种钢-竹组合结构,完成了5组共15个试件的静态双面剪切推出试验,以研究其屈服模式和破坏特征,探讨螺栓直径和竹集成材厚度对钢-竹组合结构的力学性能影响。试验结果表明:钢-竹组合结构破坏时,若竹集成材较厚,试件会发生双铰屈服,螺栓在竹集成材孔内以及H型钢翼缘孔内形成2个塑性铰,且螺栓直径较小时,会发生螺栓端头断裂;若竹集成材较薄,试件会发生单铰屈服,螺栓在H型钢翼缘孔内形成一个塑性铰,在竹集成材内保持刚直,且竹集成材会先于螺栓产生劈裂破坏。随着螺栓直径的增加,推出试件的屈服荷载、极限荷载和剪切滑移刚度均呈线性比例增加,延性无显著变化;试件的屈服荷载、极限荷载和延性随着竹集成材厚度的增加而增大,竹集成材厚度对剪切滑移刚度无显著影响。依据Johansen屈服模式Ⅲs和欧洲规范Eurocode 5考虑绳索效应,提出了适用于型钢-竹集成材螺栓连接的抗剪承载力公式,其计算值与试验值误差为12.92%,抗剪承载力计算值与试验值较吻合。

This study presented an extensive experimental investigation focusing on elucidating the performance characteristics of a novel steel-bamboo composite structure.This composite structure was composed of H-section steel components integrated with side-pressure laminated bamboo lumber and interconnected through bolt connectors.With a series of designed static push-out tests,the research endeavored to unravel the intricate yield modes and failure mechanisms inherent within this innovative composite connection.Central to the investigation was the meticulous examination of the effects of varying bolt diameters and bamboo thicknesses on the mechanical properties and structural behavior of the steel-bamboo composite structures.One key observation gleaned from the experimental results was the discernible influence of laminated bamboo lumber thickness on the yielding behavior of the composite structure.Specifically,it was observed that specimens featuring thicker laminated bamboo lumber tend to exhibit a two-hinge yielding mechanism.In such instances,the formation of two distinct plastic hinges facilitated by the bolts in the laminated bamboo lumber hole and the H-section steel flange hole.Conversely,specimens with thinner laminated bamboo lumber tend to undergo one-hinge yielding,wherein the bolt formed a singular plastic hinge in the H-section steel flange hole while maintaining rigidity in the bamboo component,leading to a different failure mode characterized by bamboo splitting before bolt fracture.Furthermore,the investigation delved into the influence of bolt diameter on crucial performance metrics such as yield load,ultimate load,shear slip stiffness,and ductility.It was established that increasing bolt diameter correlates positively with the enhanced yield load,ultimate load,and shear slip stiffness,with negligible impact on ductility.The results indicated a progressive enhancement in the specimen's resistance to deformation with an increase in bolt diameter,which was characterized by notable plastic deformation in shear resistance.Conversely,a reduction in bamboo thickness was found to adversely affect the yield load,ultimate load,and ductility,with no significant impact on shear slip stiffness.Drawing upon established theoretical frameworks such as Johansen yield mode Ⅲs and Eurocode 5,this study proposed an empirically derived equation for estimating the shear bearing capacity of steel-laminated bamboo lumber connections,duly accounting for the rope effect.Notably,the calculated shear bearing capacity closely aligned with experimental findings,with an error of 12.92%,thus validating the proposed analytical model.In summation,this study not only sheds light on the mechanical behavior of steel-bamboo composite structures,but also offers valuable insights for informing the design and optimization of such innovative construction systems in practical engineering applications.