【作者】 刘书江；

【导师】 童根树；

【作者基本信息】 浙江大学 ， 结构工程， 2004， 硕士

【摘要】 本文对钢结构中常用的格构式柱子和格构式压弯构件进行了平面内弹塑性稳定的研究。采用了两完全相同双轴对称工字型截面组成的缀条式构件作为研究对象。主要有三部分内容： 一是对运用ANSYS通用有限元程序中可以考虑几何和材料双重非线性的Beam189单元进行格构式柱和格构式梁柱的计算分析的正确性进行了研究，通过大量计算验证了此数值分析方法的正确性。 二是运用前述方法，引入整体和局部(柱肢)初弯曲和残余应力的影响，用考虑几何和材料双重非线性的有限元方法求得缀条柱的弹塑性极限承载力，通过对不同截面尺寸构件在不同长细比下的承载力计算，并从单肢稳定出发对结果进行拟合，得到了适应性更好的缀条柱平面内弯曲稳定系数φ的计算公式。 三是对我国各本钢结构设计规范中格构式压弯构件的平面内稳定计算公式与数值分析的结果进行了对比，定量地说明了当前格构式压弯构件平面内稳定性计算公式存在偏不安全的问题。运用前述方法，引入初弯曲和残余应力的影响，用考虑几何和材料双重非线性的有限元方法求得构件在不同轴力和弯矩比例作用下的弹塑性极限承载力，对不同截面尺寸构件在不同长细比下的承载力进行计算。根据数值分析结果，本文建议对格构式压弯构件采用与实腹式压弯构件相同的计算公式计算。更多还原

【Abstract】 Due to structural economy, built-up members are widely used in industrial steel structures. However, the interaction of global and local buckling occurred in built-up members and its detrimental effect on the load carrying capacity have not yet been fully documented. In this thesis the in-plane inelastic stability of laced columns and beam-columns consisting of two identical doubly-symmetrical I sections are investigated.Firstly, the validity of analyzing built-up columns and beam-columns by the general FEA program ANSYS with the Beaml89 element is studied, for the Beaml89 element can consider geometrical non-linearity and the material plasticity. Many numerical results confirm the validity of the method.Secondly, the laced columns in plastic phase are studied with the foregoing method. The overall and local initial curvatures and the residual stresses are considered, also the material plasticity is considered in the solution process. With the program, many members with different section sizes and slenderness ratios are analyzed. A better formula calculating thein-plane stability factor tp of laced columns is achieved by data fitting based on the stabilityof a single branch.Finally, formulae calculating the in-plane stability of built-up columns under compression and bending in various codes for steel structures are compared with numerical results, and it is found that the current formula is unsafe when the slenderness is large. The laced beam-columns worked in elastic-plastic range are studied. The initial curvatures and the residual stress are considered in the solution process. With the program, many members with different section sizes and slenderness ratios are analyzed. It is suggested that the same formula for in-plane stability of I-section beam-column be used for laced beam-columns.更多还原