摘要
在球面网壳的设计中,单层球面网壳的稳定性一直是关键问题,而计算模型的确定对网壳结构的稳定性分析有着至关重要的作用。通常,人们把焊接球节点的单层网壳看作刚接节点网壳,把螺栓球节点网壳看作是铰接网壳,认为其不具有抗弯能力,因而不被实际工程所采用。但实际上,螺栓球节点并不是理想的铰接节点,它具有一定的转动刚度,是介于铰接和刚接之间的一种半刚性节点,而且这种螺栓球节点网壳结构施工简便,外形美观,具有很好的工程应用价值,因此对这类半刚性节点网壳开展具有针对性的研究具有重要的实际意义。
为能够较准确的得出螺栓球节点的弯矩—转角曲线,本文通过螺栓球节点的试验研究和在ANSYS中对其进行数值模拟,研究了螺栓球节点的弯曲刚度特征,分别得到了螺栓球节点试验和数值模拟的弯矩—转角曲线,两种分析方法所得的弯矩—转角曲线吻合较好,表明了本文所提出的数值模拟方法是模拟螺栓球节点受力性能的一种正确有效的方法,从而为螺栓球节点及其它半刚性节点结构的设计与应用提供打下了坚实的基础。
在此基础上,利用上文所得的常用螺栓球节点的弯曲刚度,对k8型和k6型螺栓球节点的单层球面网壳进行了弹塑性全过程分析,系统考察了半刚性节点网壳的极限荷载和失稳模态,以及网壳的跨度、矢跨比、节点弯曲刚度、扭转刚度、节点域、荷载的分布模式、杆件类型、支承条件和初始几何缺陷等重要因素对其稳定性能的影响。通过大量的参数分析,较为全面的掌握了半刚性节点单层球面网壳的稳定性能,并借鉴现行规程中的公式形式,对以上几种参数分析中取得的大量数据进行科学的回归分析,推导出了K8型和K6型螺栓球节点网壳的稳定性验算的拟合公式。
Concerning the design of spherical shells, stability of single-layer spherical shells is the key problem, and the ascertainment of the accurate calculation-mode is very important to the analysis of the shell’s stability. Usually, shells with weld-joint system are considered as rigid-joint system and shells with bolt-joint system are generally considered as pin-joint shells,but in fact,bolt-joint has capacity of bearing partial bend,it is semi-rigid system between rigid-joint and pin-joint。Further more,because of such shell’s convenienct construction, beautiful apearence and merit of engineering application, the pertinency study of the shells with semi-rigid system has important practice purport.
To get the curve of bending moment-rotation of bolt-ball exactly ,experimental analysis and numerical simulation based on accurate and large-scale complete-process analysis are considered in this text,and the curve of bending moment-rotation of bolt-ball are educed by studying the bend rigid character of bolt-ball. The experimental results are mostly consistent with the theoretical ones, which indicate that the numerical simulation is accurate and effective to simulate the bolt-ball’s mechanical property. It can serve as stability base for design and application of the bolt-ball and other semi-rigid joints.
The shells with bolt-joint system have been detailed analyzed in this dissertation based on bend stiffness (the results of the experiments) of common bolt joint system. The elasto-plastic complete process of k8 and k6 spherical shells are studied, the ultimate strength and buckling modes of shells are obtained, the effects of stability are observed systematically by varying different spans of shells, ratio of high and span, bend stiffness, rotation stiffness, the size of joint system, the load of dissymmetrical distributing, the types of bars, the condition of support and initial geometrical imperfection. The stability of shells with semi-rigidity of joint system is mastered by a comprehensive numerical analysis. The fitting equations for the stability checking computations of K8 and K6 spherical shells with bolt-joint systerm are axquired based on the equation form in the presence regulation using a great deal of data obtained from the upwards parameter analysis.
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