【作者】 徐国际；

【导师】 舒兴平；

【作者基本信息】 湖南大学 ， 结构工程， 2010， 硕士

【摘要】 箱形截面梁由于较其它形式截面具有较好的两个主轴方向抗弯刚度和抗扭刚度,随着钢结构的不断发展,箱形构件制作工艺的完善和日趋成熟,箱形截面构件的应用越来越广,尤其是在多高层建筑中。本文主要采用有限元分析方法,研究了双轴对称箱形截面钢梁在弯矩和扭矩联合作用下的弹塑性荷载位移特性、强度极限承载力和刚度。本文的分析中考虑了由材料屈服所引起的材料非线性以及由大变形所引起的几何非线性的影响,对箱形截面钢梁在无侧向支撑时在弯矩和扭矩联合作用下的弹塑性荷载位移特性进行了分析,并和有跨中侧向支撑时梁的荷载位移特性进行了对比分析,说明了箱形截面钢梁具有较好的整体稳定性。研究还发现,在弯矩和扭矩联合作用下,由于弯曲和扭转变形所产生的几何非线性使梁跨中转角增大,并会降低扭转刚度。本文在考虑这种增大影响的基础上,提出了梁由于受到弯矩和扭矩联合作用而得到放大的跨中点截面处的二阶转角公式。本文对箱形截面钢梁在弯矩和扭矩联合作用下的弯扭相关性进行了探讨,并考虑了构件跨度、截面高宽比、高厚比及宽厚比等各因素的影响,在经过大量模型分析计算后,提出了一套基于ANSYS分析平台的对箱形截面钢梁在弯矩和扭矩联合作用下的弹塑性承载力进行分析的流程和方法,得出了箱形截面钢梁在弯矩和扭矩作用下的强度极限承载力计算公式。并指出圆曲线交互方程对本文所研究的箱形截面钢梁而言,有其局限性。最后,本文对兼承扭矩的箱形截面钢梁的刚度进行了探讨和研究,得出了在刚度控制条件下弯曲和扭转联合作用时梁的承载力计算公式。该公式是对弹性状态下梁受跨中集中荷载时的挠度计算公式进行修订,考虑了受弯构件同时受扭的影响,把扭矩转化成相应的弯矩来计算跨中的挠度值。本文对箱形截面钢梁在弯矩和扭矩联合作用下的受力性能进行了研究,所得计算公式供规范修订和工程设计参考。更多还原

【Abstract】 With the continuous development of steel structure and the producing process of component member improving and becoming more mature, steel box girder, due to its good bending stiffness of the two axis directions and torsional stiffness, compared with other forms, is more widely used in application now, especially in the high-rise building.In this paper, the elastic-plastic load-deformation relationships, ultimate strength and stiffness of steel box girder are investigated by using the finite element method (FEM) under combined bending and torsion. Taking into account the effects of large deformation, material inelasticity and geometric imperfections, the characteristics of load-deformation relationships are analyzed of steel box girder with no lateral supporting, and then compared with that of box girder with mid-point supporting, illustrating that steel box girder has a better overall stability. The study also found that the first-order rotation due to pure torque may be amplified by flexural-torsional buckling effects, which reduce the effective torsional stiffness. Then the amplified elastic twist rotation formula is suggested, taking into the effects.The study also found that the combined effects of bending moment and torque, due to bending and torsional deformation of the geometric nonlinearity arising in the corner across the beam increased, this increase in considering the impact of this proposed based on the beam as by the combined effects of the bending moment and torque are enlarged cross-section mid-point of the corner office of the second order formula.The interactions between in-plane bending and torsion are studied, considering the member span, section properties, the thickness of the flange and the web and other factors. A practical user-defined inelastic analysis procedure based on ANSYS program is proposed after analyzing a large number of models, and the ultimate strength formula for the design of steel box girder under combined bending and torsion is proposed. It is found that a commonly quoted circular interaction equation for combined bending and torsion dose not always provide a true lower bound for steel box girder.Finally, some research and discussion are conducted on the bending stiffness of steel box girder under combined bending and torsion and the carrying capacity formula of steel box girder under the control of stiffness conditions is obtained, which is a revised formula. The purpose of the formula is to calculate the mid-span deflection under concentrated load in elastic state, taking into account the effect of torsion at the same time and making some modification of the torque into appropriate bending moment, then to sum up to the two parts of moment to calculate the deflection of steel box girder.In this paper, some research on the carrying properties of steel box girder under combined bending and torsion is conducted, and the formulas proposed can be applied in Practical Engineering Design.更多还原