轴向约束圆管高温力学响应全过程数值模拟

Numerical Analysis on the Whole Process of Mechanical Response of Axially Restrained Members under High Temperature

不同于已有大量研究的框架柱,网架结构中的压杆是典型的轴心受压构件,其圆形截面的几何特点与H形截面不同,杆件的长细比和受到的约束与框架柱也存在差异。根据构件的受力特点,建立轴向约束圆管的有限元计算模型,采用ABAQUS软件对升温条件下约束构件开展力学反应全过程数值模拟分析。使用粘滞阻尼法进行非线性屈曲分析,通过验证选取合适的粘滞阻尼力来促进屈曲阶段计算的收敛。分析了轴向约束刚度比、荷载比和长细比的影响,给出了约束圆管跨中挠度、轴力和竖向位移随温度的变化关系,并分析了屈曲后承载力的变化规律,为进一步建立网架整体模型,研究网架结构受火失效机理奠定了基础。

The compression bars in grid structures are typical axial compression members.Little research is conducted in this area.The geometric characteristics of circle section are different from H section.Slenderness ratio of the members and frame columns is very different and they suffer from different restriction.A finite element model of axial compression member is established based on the performance of the member.Mechanical response of axially restrained members under fire is simulated using finite element software ABAQUS.Viscous damping is introduced to perform nonlinear buckling analysis of the restrained members,and this helps to improve the convergence rate in the buckling stage.Based on the numerical example,this paper shows how the mid span cross-section deflections,axial force and axial displacement change with temperature.Many scenarios are considered including different axial restraint stiffness ratio,load ratio and slenderness ratio.Moreover,the analysis of the influence regularities of post buckling loadbearing capacity is presented.These research results provide a reference for further studies of the failure mechanism of spatial grid structures under fire.