【作者】 徐伟；

【导师】 周绪红；

【作者基本信息】 长安大学 ， 结构工程， 2008， 硕士

【摘要】 本论文主要完成了以下工作:(1)根据有限变形理论三维虚功增量方程,采用更新的UL列式法,推导出交错桁架结构整体稳定分析的单元刚度矩阵,该刚度矩阵综合反映了单元的剪切效应、二阶效应、翘曲分布、半刚性连接、单元初应力刚度等因素的影响,同时建立交错桁架结构的非线性有限元力学模型,为钢结构交错桁架体系计算软件的编制提供理论基础。(2)运用门槛刚度将交错桁架划分为强、弱支撑交错桁架,其目的是为了运用传统的计算长度系数法来考虑结构的稳定性。通过算例分析可知建筑的高宽比和桁架的跨高比对结构的二阶效应具有很大的影响,因此在分析中应引入二阶分析方法来考虑结构的整体稳定性。(3)对结构整体稳定的判定准则进行了研究,并以此为依据提出了高层交错桁架体系的整体稳定判定准则,即依据荷载—位移曲线切线斜率控制和单元刚度矩阵(正定)控制。并且根据直接P-Δ分析法,提出考虑整体二阶效应的简化计算方法,从而大大提高了计算效率。并且根据研究,对高层交错桁架体系整体稳定性的设计提出了一些建议。更多还原

【Abstract】 The following works have been fulfilled within this thesis: First of all, based on the three-dimensional Virtual Work increment equation of Finite Deformation Theory, applied Updated Lagrange Method, and deduced geometric stiffness matrix of elements considering factors, such as the influence of shear force, second-order effects, warp distribution and section opening and close, and geometric initial stress stiffness. Meanwhile, establishing nonlinear finite element mechanical model of Staggered-truss System, offering theoretical evidence for the compilation of calculation software of the System.Secondly, Staggered-truss System be divided into strong-bracing and weak-bracing staggered truss by threshold stiffness of bracing, the objective is to use traditional coefficient for effective length to consider structure stability. It was clear from the height-width ratio of architecture and the span-depth ratio of truss impact greatly on second-order effects by analysis of examples; therefore, Second-Order Analysis Method should be introduced in analysis to consider structure stability.Finally, according to test on Judgment criteria of overall stability of the structure, presenting Judgment criteria of overall stability of Staggered-truss System in high-rise buildings, that is based on the load-displacement curve and slope of tangent line-controlled and element stiffness matrix (positive definite)-controlled. Moreover, using the Direct P-Δanalytic method, putting forward to considering simplified design method of the whole Second-order effects, thus greatly improving computational efficiency. In addition, also to the design of Overall Stability has made some suggestions.更多还原