【作者】 朱健；

【导师】 龙莉萍；

【作者基本信息】 重庆大学 ， 结构工程， 2009， 硕士

【摘要】 圆钢管由于其独特的优越性能被广泛应用于桁架结构中。作为整个结构的有机组成部分,钢管之间的连接即节点设计是一个重要的方面。不同轴线钢管构件之间的连接型式之一是采用相贯节点形式。在实际工程中的平面KT型圆钢管相贯节点是经常出现的节点形式,它由三根支管汇交于一根主管表面构成,现有公式中并没有专门针对KT型节点的承载力计算公式,故须针对这种节点开展全面的静力性能研究。本文利用ANSYS有限元程序分析了各参数对该类节点极限承载力的影响,获得了极限承载力随各几何参数的变化规律以及节点破坏模式,考察了主管所受轴压力大小对节点承载力的影响,修正了现有CIDECT的计算公式,并提出了对工程设计有益的建议,供工程设计人员和修订规范时参考。主要研究内容如下:首先,对节点进行ANSYS建模,通过对比分析确定了对节点进行有限元计算时使用到的若干条件,如边界条件、加载比例等。选取了一个桁架上弦KT型节点,按照桁架中节点各支杆内力比例对所研究节点的支杆施加轴力。其次,对96个KT型节点进行了非线性分析。分析时考虑了四个无量纲参数,即支管直径与主管的直径之比β;主管的直径与壁厚之比γ;支管壁厚与主管壁厚之比τ;以及中支管与边支管的搭接率OV对KT型节点破坏模式和极限承载力的影响。分析结果揭示了各参数对节点承载力的影响规律,阐述了节点三种主要破坏模式:支管强度破坏、主管上表面塑性破坏和主管向上弯曲破坏。并得到了主管在轴压力不断增大的情况下,节点承载力有所下降得结论。最后,将ANSYS的结果与CIDECT公式计算结果进行对比,并通过一元线性回归分析,对公式进行了修正,使其更为准确。更多还原

【Abstract】 Steel tubes have been widely used in truss structures because of excellent properties. As organic component of whole structure, design of tube-to-tube connections is a important aspect. Connections between hollow section members are usually configured by welding one member directly to the surface of the other. Directly welded KT-type CHS(Circular Hollow Section)joints,which are made up of three branchs and one chord,are very common in the design of trusses.There isn’t any formula for the direct calculation of KT-type joints strength.It is necessary to investigate static behaviour of Circular-Hollow-Section KT-joints in all aspects.By using ANSYS PROGRAM, the effect of the various geometric parameters on ultimate bearing capacity has been investigated. The regulations that the ultimate strength varies with geometric parameters and the destroying models of joints are obtained. The effect of stress of the chord on the ultimate strength is also investigated and the current formula of CIDECT is revised. Some constructive suggestions to the engineering design are put forward for reference in design and code revision.Here are the main content:Firstly, the ANSYS model of the joint is constructed.Through the contrastive analysis,several conditions as boudary condition、loading condition used in FEA(finite element analysis)are fixed.The loading proportion of the branchs is got from the KT-type joint in the upper chord of the truss.Then , Analysis of nonlinear finite-element for ultimate strength of 156 tubular KT-joints is carried out.The influence of nondimensional joints parametersβ、γ、τ、OV and a on failure mode and ultimate strength of tubular KT-joints is studied.The effect law of these parameters to the ultimate strength of KT-joints is described,and there are three major failure modes:branch strength failure、chord failure and chord bending failure.The ultimate strength of the KT-joints goes down under the force of the chord.Finally,the results of ANSYS are compared with that of CIDECT formula. By the linear regression analysis,the formula is revised in order to make its results more accurate.更多还原