木榫旋转焊接节点剪切试验研究与理论分析

为研究无胶层合木梁中旋转焊接木榫的抗剪性能,选用山毛榉木榫旋转焊接SPF(spruce-pine-fir)层板,制备20个单榫焊接节点试件开展双剪试验,获得其破坏模式及荷载-位移曲线。试件的破坏模式为木榫受剪出现类双铰破坏,同时开孔附近基材受木榫挤压破坏。试件的平均峰值位移为4.460 mm,平均峰值荷载为6.127 kN。分别采用中国GB 50005—2017《木结构设计标准》、美国NDSWC-2018木结构设计规范、欧洲Eurocode 5-1995木结构设计规范中金属销类连接件抗剪承载力公式进行计算。结果表明,因木榫与金属销的弹塑性行为差别较大,且木榫旋转焊接节点绳索效应不明显,上述规范计算误差均大于30%。基于破坏模式分析,本研究提出适用于旋转焊接木榫的抗剪承载力计算公式,计算误差为13.76%。进一步采用ABAQUS开展有限元分析,利用Cohesive Behavior模拟旋转焊接界面层。有限元结果与试验结果吻合较好,能够较为准确地预测剪切试验中旋转焊接木榫的类双铰破坏模式,承载力预测误差为13.17%。上述试验研究与理论分析为木榫旋转焊接技术在无胶层合木梁中的应用提供设计参考和理论依据。

Shear tests and theoretical analysis of wood-dowel rotation welding joints

In order to study the shear resistance of the rotation welding dowel in adhesive-free laminated wood beams,the beech dowel was selected to connect the spruce-pine-fir(SPF)laminates by the rotation-welding technique.Twenty joint specimens with single dowel were prepared and tested.The double shear tests were conducted to obtain the shear performance of the joint specimens.The failure modes and load-displacement relationships were recorded and analyzed.It was found that the dowels failed with similarly double-hinge failure modes,and the substrates around the hole showed localized compressive damages.The average displacement at the maximum load reached 4.460 mm,and the average maximum load was 6.127 kN.The calculations were carried out using the formulas of the shear resistance of metal dowel connectors from the Chinese standard GB 50005-2017 Wooden Structure Design Standards,the American code NDSWC-2018 Wood Structure Design Code,and the European code Eurocode 5-1995 Wood Structure Design Code.The results showed that the calculation errors of the above formulas were larger than 30%.It was because that the elastoplastic behavior was greatly different between the wooden and metal dowel connectors,and there was less rope effect provided by the rotation welding dowel connector.Considering the failure mode and damage distribution,a formula to predict the shear resistance of the rotation welding dowels was proposed and verified.The calculation results were in good agreement(13.76%error)with the test results.Furthermore,the ABAQUS software was used to carry out the finite element analysis,in which the cohesive behavior was used to simulate the rotation welding interface.The results of the finite element analysis were in good agreement with the test results,which could accurately predict the double-hinge failure mode of the rotation welding dowel in the shear tests.In addition,the numerical bearing capacity was slightly larger than the experimental result,which had an error of 13.17%.The above experimental and theoretical analyses provided the design reference and theoretical basis for the application of dowel rotation welding technology to adhesive-free composite beams.