火灾下轴向约束钢梁的样条有限元法

Spline Finite Elements Methods to Axially Restrained Steel Beams in Fire

提出了一种同时考虑几何非线性和材料非线性的平面样条梁单元,并用其进行了火灾升温条件下沿截面温度分布不均匀轴向约束钢梁的受力分析.以节点的弯矩和轴力平衡为条件建立基本方程,可方便地考虑轴力的二阶效应和升温条件下材料的非线性,并可考虑温度沿截面的任意分布形式,避免了常规有限元法在单元刚度矩阵中考虑这些因素的复杂性.算例表明,该样条梁单元有足够的精度,且求解速度快于常规有限元法的壳单元.

A spline beam element method is presented to analyze the nonlinear behaviours of axially restrained plane steel beams in fire, and study the catenary action effect of axial force and material nonlinearity of steel at elevated temperatures. The governing equations are based on the internal-and external-force equilibriums at every discrete node. This strategy can avoid the complexity of accounting for the second-order effect of axial force and elastic-plasticity of steel material in the element stiffness matrix; at the same time, it can deal with arbitrary temperature distribution across the section. Compared with the shell element of traditional finite element method, the spline beam element method is precise and computationally economical.