摘要:
单层铝合金网壳具有自重轻、耐腐蚀、外形优美等诸多优点,近年来被广泛应用于大跨空间结构。由于板式节点构造简单且安装方便,已成为单层铝合金网壳最常用的节点形式之一。但由于该节点仅通过盖板与铝合金梁的翼缘连接,而与腹板并不连接,导致其抗剪承载力及面内轴向刚度严重不足,容易发生失稳破坏,不能满足大跨度铝合金网壳对节点性能的需求。为此在现有节点的基础上,提出一种新型花环齿槽组合节点。为探究新型铝合金花环齿槽节点的抗剪性能和破坏形态,对新型节点和传统板式节点进行了抗剪试验,获得了两种节点在面外荷载下的失效模式和荷载-位移曲线,并分析了新型花环齿槽节点的抗剪性能。运用ABAQUS软件对新型节点的加载全过程进行数值模拟分析,并验证了有限元模型的可靠性。结果表明,板式节点的破坏模式主要表现为盖板的拉剪破坏,铝合金梁并未发生明显的弯曲破坏;新型节点的破坏模式主要表现为铝合金梁的弯曲破坏,盖板发生翘曲以及花环齿槽体撕裂,这主要是由于新型节点中的花环齿槽体有效分担并传递了很大一部分剪力。花环齿槽体改变了传统板式节点的传力方式和破坏形态,将铝合金梁腹板连接成一体,更加有效地分担并传递了剪力,减轻了盖板的剪力负担,提高了节点的抗剪性能,从而改变了板式节点脆性破坏的缺点,使其具有良好的延性和耗能能力。由于新型节点的中心区域设置了花环齿槽体,因此相对于传统板式节点,新型节点的抗剪承载力提高了47.4%,抗剪刚度提高了103.9%,具有良好的工程应用前景。对新型节点的有限元分析结果表明,有限元解析得到的荷载-位移曲线的线性段吻合较好,与实测位移的误差在5%以内,抗剪承载力误差仅为0.14%,验证了有限元模拟结果的可靠性。当新型节点承受极限荷载时,上、下盖板与杆件相接的部位应力较大,而上盖板大部分区域都进入了塑性,下盖板仅小部分区域进入塑性,螺栓孔处以及花环齿与槽体的交接处均出现应力集中现象。
Abstract:
Single-layer aluminum alloy latticed shell has many advantages such as light weight,corrosion resistance and beautiful shape,which has been widely used in large-span spatial structures in recent years.Because of the simple structure and convenient installation,plate joint has become one of the most commonly used joint forms of single-layer aluminum alloy reticulated shells.However,because the joint is only connected with the flange of aluminum alloy beam through the cover plate,but not connected with the web,the shear bearing capacity and in-plane axial stiffness of the joint are seriously insufficient and prone to instability and failure,which can not meet the performance requirements of large-span aluminum alloy reticulated shells.In this paper,on the basis of the existing joints,a new type of flower-gusset joint is proposed.In order to explore the shear performance and failure mode of the new aluminum alloy flower-gusset joint,the shear tests of the new type of joint and the traditional plate joint are carried out in this paper.The failure modes and load-displacement curves of the two joints under the out-of-plane load are obtained,and the shear performance of the new type of flower-gusset joint is analyzed.ABAQUS software was used to conduct numerical simulation analysis on the whole loading process of the new type of joint,and the reliability of the finite element model was verified.The results show that the failure mode of plate joints is mainly the tensile-shear failure of the cover plate,and there is no obvious bending failure of the aluminum alloy beam.The failure mode of the new type of joint is mainly manifested as the bending failure of the aluminum alloy beam,the warping of the cover plate and the tearing of the flower-gusset,which is mainly due to the effective sharing of the flower-gusset in the new type of joint and the transfer of a large part of the shear force.The flower-gusset changes the force transmission mode and failure mode of the traditional plate joint,and the aluminum alloy beam webs are connected through it to form an integrated body,which more effectively shares and transmits the shear force,reduces the shear load of the cover plate,improves the shear performance of the joint,thus changing the shortcomings of the brittle failure of the plate joint,so that it has good ductility and energy dissipation capacity.Therefore,compared with the traditional plate joint,the shear bearing capacity of the new joint is increased by 47.4% and the shear stiffness is increased by 103.9% due to the addition of the annular groove in the central area of the new joint,which has a good prospect for engineering application.The finite element analysis results of the new joint show that the linear segment of the load-displacement curve obtained by the finite element analysis is in good agreement with the measured displacement,the error is less than 5%,and the error of the shear bearing capacity is only 0.14%,which verifies the reliability of the finite element simulation results.When the new type of joint is subjected to the ultimate load,the partial stress of the upper and lower cover plates connected with the bar is large.However,most areas of the upper cover plate are plastic,and only a small part of the lower cover plate is plastic.Stress concentration occurs at the bolt hole and the junction of the ring tooth and the groove body.
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