摘要:
近年来单层铝合金网壳被广泛应用于大跨空间结构,最常用的节点形式为板式节点。单层网壳的节点同时承受轴力和弯矩的作用,目前已有的研究成果大部分集中于板式节点抗弯性能,对其轴向性能的研究工作较少。针对以上研究现状,以板式节点轴向性能为研究对象,开展了抗压试验,并建立对应的数值分析模型。试验与数值模拟对比结果表明,板式节点轴向荷载-位移曲线包含4个阶段:弹性阶段、螺栓滑移阶段、孔壁承压阶段和失效阶段。试验和数值模拟的荷载-位移曲线较为一致,破坏模式均为沿梁端螺栓孔处破坏。显然,数值模型非常准确,可用于后续参数化分析。为此建立不同螺栓间隙、螺栓预紧力、螺栓数量的数值分析模型,对板式节点的轴向性能开展参数化分析。分析结果显示:1)随着螺栓间隙的增加,螺栓嵌固阶段的荷载-位移曲线基本重合,螺栓滑移距离逐渐增大,孔壁承压阶段轴向刚度和极限荷载基本一致;2)随着螺栓预紧力的增加,螺栓滑移阶段的初始荷载逐渐增加,滑移距离基本不变,孔壁承压和失效阶段荷载-位移曲线完全重合;3)随着螺栓数量的减少,板式节点的轴向承载力降低最为明显,抗剪承载力次之,抗弯承载力降低幅度最小。在对节点进行等强设计时,应按轴向承载力相等的原则来确定螺栓的数量。在试验研究和数值分析的基础上,对板式节点轴向刚度模型开展研究。根据试验和数值模拟所得到的荷载-位移曲线可知,采用多折线简化模型来描述板式节点在轴力作用下的变形机理是可行的。然后基于板式节点在轴力作用下的变形和传力机理,推导出了多折线简化模型的计算公式。并将简化模型与试验和数值模拟结果对比发现:在弹性阶段、滑移阶段及孔壁承压阶段,简化模型与试验和数值模拟结果非常吻合;在失效阶段,简化模型的极限弯矩略小于试验和数值模拟结果。显然,推导出的多折线轴向刚度模型满足精度需求,同时具有足量的安全余度。
Abstract:
In recent years,single-layer aluminum alloy reticulated shells are widely used in long-span spatial structures,and the most commonly used joint form is plate joint.The joints of single-layer reticulated shells bear both axial force and bending moment.At present,most of the existing research results focus on the flexural performance of plate joints,and there is less research on their axial performance.In view of the above research status,this paper takes the axial performance of plate joints as the research object,carries out compressive tests,and establishes the corresponding numerical analysis model.The comparison results of test and numerical simulation show that the axial load-displacement curve of plate joints includes four stages:elastic stage,bolt slip stage,hole wall bearing stage and failure stage.The load-displacement curves of the test and numerical simulation are consistent,and the failure modes are all along the bolt hole at the beam end.Obviously,the numerical model is very accurate and can be used for subsequent parametric analysis.The numerical analysis models of different bolt clearance,bolt preload and bolt quantity are established to carry out parametric analysis on the axial performance of plate joints.The results of parametric analysis show that:1) with the increase of bolt clearance,the load-displacement curve of bolt embedding stage basically coincides,the bolt slip distance gradually increases,and the axial stiffness of hole wall in pressure stage is basically consistent with the ultimate load.2) With the increase of bolt preload,the initial load in bolt slip stage gradually increases,the slip distance is basically unchanged,and the load-displacement curve of hole wall bearing and failure stage completely coincide.3) With the decrease of the number of bolts,the axial bearing capacity of plate joints decreases most obviously,the shear bearing capacity takes the second place,and the reduction of flexural bearing capacity is the smallest.In the equal strength design of joints,the number of bolts should be determined according to the principle of equal axial bearing capacity.On the basis of experimental research and numerical analysis,the axial stiffness model of plate joints is studied.According to the load-displacement curve obtained from test and numerical simulation,the multi broken line simplified model can be used to describe the deformation mechanism of plate joints under axial force.Then,based on the deformation and force transmission mechanism of plate joints under axial force,the calculation formula of multi broken line simplified model is deduced.Comparing the simplified model with the experimental and numerical simulation results,it is found that the simplified model is in good agreement with the experimental and numerical simulation results in the elastic stage,sliding stage and hole wall pressure stage.In the failure stage,the ultimate bending moment of the simplified model is slightly smaller than the test and numerical simulation results.It is obvious that the derived multi broken line axial stiffness model satisfies the accuracy and safety requirements at the same time.
登录
注册
点击查看大图
下载:
