火灾下不同拉剪组合对螺栓节点性能影响的研究

发布时间：2018-06-09 13:20

本文选题：螺栓节点 + 火灾　；参考：《清华大学》2013年硕士论文

【摘要】：节点是结构受力的关键部位，梁和柱的内力通过节点传递，节点的破坏甚至可能引发结构的连续性倒塌，因此分析节点真实受力行为对于考察结构的安全性尤为重要。常温下节点变形较小，承受的荷载组合相对简单和固定，多考虑其承受剪力或弯矩作用的行为。火灾中节点的承载力随着温度的升高而降低，高温下的大变形导致梁沿轴向产生悬链拉力作用。此时，一方面节点要有足够的转动能力以容纳梁的变形，另一方面节点的受力状态发生明显改变，节点应具有足够的抗拉能力，否则会在拉剪共同作用下发生破坏。然而，目前国内外有关节点高温研究的内容主要还是遵循节点常温研究的思路，即通过试验或有限元方法得到独立节点的弯矩-转角关系，对于火灾中节点的真实受力及节点与构件间的相互作用缺少考虑。因此，有必要开展节点在拉、弯、剪综合荷载作用下的真实火灾行为的研究。本文主要研究内容包括： (1)采用自定义双线性炉温控制曲线，进行了端板式螺栓连接及腹板双角钢式螺栓连接两种不同形式节点的火灾试验，以端板厚度、火灾荷载组合为主要参数，研究了高温下钢结构节点的温度分布、破坏模态、承载力、变形及拉剪组合作用对节点承载力的影响等。 (2)建立了节点的三维实体分析模型，模型中考虑了材料非线性、节点大变形及节点各组件间的接触关系对节点性能的影响。并采用试验结果对有限元模型进行了验证分析，结果表明有限元方法可以准确地模拟出节点受力及变形，同时可以方便地得到节点整个破坏过程。接着，通过大量的节点荷载组合参数分析，研究了节点在拉剪组合作用下的破坏机制及剪力对节点抗拉承载力的影响，得到了节点在拉剪组合作用下对应不同极限温度的相关破坏曲线。 (3)基于组件法建立了平齐式端板节点的简化分析模型，并利用试验及三维有限元分析的结果对模型进行验证。所建立的模型通过螺栓抗拉强度的折减考虑了剪力对螺栓承载力的影响，因此可以方便地得到节点在同时承受拉、剪、弯的综合荷载作用时的性能。通过一系列的参数分析，，进一步得到了剪力及拉力对节点火灾行为的影响，并为钢结构节点高温设计提出设计建议。
[Abstract]:The internal force of beam and column is transmitted through the joint, and the destruction of the joint may even lead to the continuous collapse of the structure. Therefore, it is very important to analyze the real behavior of the joint in order to investigate the safety of the structure. At room temperature, the joint deformation is small, the load combination is relatively simple and fixed, and the behavior of the joint subjected to shear or bending moment is considered. The bearing capacity of the joints decreases with the increase of the temperature, and the large deformation at high temperature results in catenary tension along the axial direction of the beam. At this point, on the one hand, the joint should have enough rotation ability to accommodate the deformation of the beam, on the other hand, the stress state of the joint should be changed obviously, and the joint should have sufficient tensile capacity, otherwise, the joint would be destroyed under the joint action of tension and shear. However, at present, the contents of the research on the joint temperature at home and abroad mainly follow the train of thought of the research on the normal temperature of the joint, that is, the moment-rotation relationship of the independent joint is obtained by means of the experiment or the finite element method. There is a lack of consideration for the actual force of the joint and the interaction between the node and the component in the fire. Therefore, it is necessary to study the real fire behavior of joints under tension, bending and shear loads. The main contents of this paper are as follows: (1) using the self-defined bilinear furnace temperature control curve, the fire tests of end plate bolt connection and web double angle steel bolt connection are carried out, and the thickness of the end plate is taken as the thickness of the end plate. The influence of temperature distribution, failure mode, bearing capacity, deformation and tension shear combination on the joint bearing capacity of steel structure under high temperature is studied. In the model, the material nonlinearity, the large deformation of the joint and the contact relationship between the various components of the joint are considered to affect the performance of the joint. The finite element model is verified and analyzed by the experimental results. The results show that the finite element method can accurately simulate the stress and deformation of the joints and the whole failure process of the joints can be easily obtained. Then, through the analysis of a large number of joint load combination parameters, the failure mechanism of joints under the action of tension and shear combination and the influence of shear force on the tensile bearing capacity of joints are studied. The relative failure curves of joints corresponding to different limit temperatures are obtained. (3) based on the component method, a simplified analysis model of flat end plate joints is established, and the model is verified by the results of experiments and 3D finite element analysis. The model considers the effect of shear force on the bearing capacity of bolts by reducing the tensile strength of bolts, so it is convenient to obtain the performance of the joints under the combined loads of tension, shear and bending at the same time. Through a series of parameter analysis, the influence of shear force and tensile force on the joint fire behavior is further obtained, and the design suggestions for the high temperature design of steel structure joint are put forward.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU352.5

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