Study on Stiffness and Ultimate Behavior of Multi-Planar Joints for Tubular Space Trusses

研究了空间K型相贯节点的极限承载力，K型相贯节点是空间相贯节点中最具代表性的节点。推导了对称轴力作用下双K型节点的两种极限承载力计算公式。第一种方法具有最佳的精度，变异系数（COV）为0.06，而第二种方法通过略微放弃精度（COV=0.1）进行了简化。推导了反对称轴力支撑作用下双K型相贯节点的极限承载力计算公式。这些方程的基础上不仅实验结果，而且有限元分析结果，后者已经通过与斯旺西大学学院的研究人员合作研究获得。另一个重要的问题是，我们过去提出的强度预测方程可能会在具有非常重的弦的接头的不安全方面出错，这是由斯旺西的同一调查人员提出的， ...更多信息 也被研究过。实验和数值计算结果表明，我们提出的方程是适用于这样的重弦杆节点。通过这些研究，找出了将试验结果与数值计算结果相结合来评估管节点极限承载力的一些基本要求，从而明确了多平面节点的极限性能。目前正在继续努力建立适用于所有多平面接头的设计规则。提出了几个初步的设计公式。为此，建立了一个包含2000个试验和数值计算结果的数据库（节点）。关于框架和节点之间的相互作用，本文得出以下结论：1.当节点的失效是桁架结构的第一个失效事件时，我们提出的极限承载力方程可以准确地预测节点的承载力.当构件的屈曲是第一个破坏事件时，节点的破坏荷载低于我们的公式所预测的荷载，这是因为在构件屈曲后发生了应力重分布.桁架在构件屈曲后的极限性能可以通过考虑应力重分布影响的分析来再现。然而，这种分析对于设计实践来说太复杂了。设计的一种替代方法是将节点设计为具有比构件屈曲荷载大25%的承载力。在后一种情况下，需要进行桁架结构的抗震设计，其中包括屈曲后能量吸收能力。少

The ultimate behavior of tubular double K-joints, which are the most representative joints among diverse multi-planar joints, was studied. Two types of ultimate capacity equations for double K-joints under symmetrical axial brace loading were derived from this study. The first one has the best possible accuracy with a coefficient of variation (COV) of 0.06, while the second one was simplified by relinquishing accuracy slightly (COV=0.1). Ultimate capacity equations with good accuracy were also derived for double K-joints under anti-symmetrical axial brace loading. These equations are based not only on experimental results but also on finite element analysis results, the latter ones having been obtained through a cooperative research with investigators in University College Swansea. Another important topic that our strength prediction equations proposed in the past may err on the unsafe side for joints with extremely heavy chords, which was argued by the same investigators in Swansea, w … More as also studied. Both experimental and numerical results showed that our proposed equations are applicable to joints with such heavy chords. Through these investigations some principal requirements for combining experimental and numerical results to evaluate ultimate capacities of tubular joints were found.From this onvestigation the ultimate behavior of multi-planar joints was made clear. Efforts are now being continued to establish design rules applicable to all the multi-planar joints. A few tentative desigh equations have already been proposed. For this purpose a database including 2000 data sets (joints) from both experimmental and numerical results have been prepared.With regards to interactions between frame and joint behavior, the following conclusions have been drawn :1. When a failure of a joints is the first failure event in a truss structure, our proposed ultimate capacity equations accurately predict the capacity of the joiint.2. When bucking of a member is the first failure enent, joints fail at loads lower than those predicted by our wquations owing to stress re-distribution taking place after bucking of members.3. The ultimate behavior of trusses after bucking of members can be reproduced by an analysis that takes into account effects of stress re-distribution. However this analysis is too complex for the use in design practice. An aternative method of design is to design the joints to have capacities 25% greater than buckling loads of members. In this latter case an earthquake resistant design of truss structures that includes post-buckling energy absorbing capacity bees performed. Less