斜腿框架体系的稳定性分析

发布时间：2018-01-13 00:36

本文关键词：斜腿框架体系的稳定性分析　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：斜腿框架相对于常见的直腿框架(普通框架)有其受力的特点和优点,在直腿框架中主要以杆件的弯曲来传力,杆件中弯矩和剪力较大。而在斜腿框架中除了有弯曲传力外,还多了一种“拱”的传力方式,因此,在斜腿框架中轴力较大。由于有“拱”的传力方式,斜腿框架的变形刚度比普通框架大,在同样的荷载和杆件截面情况下,斜腿框架可跨越的空间(跨度)更大,或者在同样的跨度下,斜腿框架的杆件截面可以做的更小。但这会使得斜腿框架的稳定问题变得突出和重要,加之斜腿框架中的轴力也相对较大。稳定问题的核心是评估和确定杆件或结构的临界力。对于普通框架可借助《钢结构设计规范》附录D来确定框架柱的计算长度系数,而对于斜腿框架就没那么幸运了,在常用规范中还没有见到相关的计算公式或表格。工程中也不可能针对具体的结构去推导和求解稳定临界方程,因临界方程式超越方程,无解析解,须迭代求解。虽然当今可用软件计算来取代大量的手算,但软件计算结果的正确性也需要检验,用什么来检验,怎样检验?这些也是不能回避的问题。因此工程设计还是迫切需要一些既方便又快速的计算工具。本论文就是针对这一现状来开展工作:对斜腿框架的稳定进行研究,推导相关的临界方程,进而求解和大量求解,以获得足够多的数据,来绘制能计算斜腿框架柱临界力的诺模图。因此本文最有价值的成果就是附表1至附表3中的诺模图,这些诺模图的计算结果经过了有限元(ansys软件)计算的检验,检验结果是正确可靠,计算精度高。由于稳定问题比传统的一阶强度问题复杂,要考虑结构变形后的平衡,属于二阶问题,是几何非线性。精确推导结构的稳定临界方程会随着结构杆件及节点数目的增多变得异常困难,因此本论文仅选取了单跨斜腿框架为研究对象,但本文研究方法可以扩展到多跨的情况。值得一提的是:在研究斜腿框架的稳定特点及规律时,作者找到了合适的方法,可用来定性或定量的考察与斜腿框架临界力密切相关的参数(约束和刚度)的影响,为此引入了新的概念,即全刚度约束、半刚度约束和零刚度约束。用这些概念包含的知识来考察结构中杆件对柱子提供的约束大小,有很好的帮助。也能清晰的解释为什么斜腿框架比同样尺寸的直腿框架的临界力低。
[Abstract]:The oblique leg frame has the characteristics and advantages of force compared with the common straight leg frame (common frame). In the straight leg frame, the bending of the bar is mainly used to transmit the force. The bending moment and shearing force are larger in the members. In addition to the bending force transmission in the oblique leg frame, there is also one kind of "arch" force transfer mode, therefore, the axial force is larger in the oblique leg frame. Because of the "arch" transmission mode. The deformation stiffness of the oblique leg frame is larger than that of the ordinary frame. In the case of the same load and member section, the inclined leg frame can span more space (span), or under the same span. The cross section of the inclined leg frame can be smaller, but this will make the stability of the inclined leg frame become prominent and important. The core of the stability problem is to evaluate and determine the critical force of the member or structure. For the common frame, the calculation length of the frame column can be determined by using Appendix D of the Code for Design of Steel structures. Degree coefficient. But for the oblique leg frame is not so lucky, there is no related calculation formula or table in the common specification, and it is impossible to deduce and solve the stability critical equation for the specific structure in the engineering. Because the critical equation transcends the equation and has no analytic solution, it has to be solved iteratively. Although a large number of manual calculations can be replaced by software calculation nowadays, the correctness of the software calculation results also needs to be tested. What should be used to test and how to test? Therefore, engineering design is in urgent need of some convenient and fast computing tools. This paper is aimed at this situation to carry out the work: to study the stability of oblique leg frame. The related critical equations are derived, then solved and solved in large quantities to obtain enough data. Therefore, the most valuable result of this paper is the Norm diagram in schedules 1 to 3. The calculation results of these Norm diagrams have been verified by finite element software ANSYS. The results are correct and reliable, and the calculation accuracy is high. The stability problem is more complicated than the traditional first-order strength problem. In order to consider the structural equilibrium after deformation, it belongs to the second order problem and is geometric nonlinear. It is very difficult to derive the stability critical equation of the structure with the increase of the number of structural members and nodes. Therefore, this paper only selects the single-span oblique leg frame as the research object, but this research method can be extended to the multi-span case. The author has found a suitable method for qualitative or quantitative investigation of the influence of parameters (constraints and stiffness) closely related to the critical force of the oblique leg frame. For this reason, a new concept is introduced, that is, full stiffness constraint. Semi-stiffness constraints and zero-stiffness constraints. The knowledge contained in these concepts is used to investigate the size of the constraints provided by the members of the structure to the columns. It also clearly explains why the oblique leg frame has a lower critical force than a straight leg frame of the same size.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU391

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