带有残余应力的钢梁内嵌式预应力组合梁抗火性能研究

Fire Resistance of Steel Beam Embedded Prestressed Composite Beam with Residual Stress

为研究残余应力对钢梁内嵌式的预应力简支组合梁在火灾效应下的受力性能的影响,通过ABAQUS软件建立钢梁内嵌式的预应力简支钢-混组合梁几何非线性和材料非线性的有限元模型,利用热力-耦合法计算组合梁在高温下的结构响应行为。通过对梁的截面温度、整体挠度和跨中挠度、跨中截面应力分布、拉索应力和塑性变形、梁的整体曲率和跨中曲率等特性在高温下的结构响应进行考察,探究工程应用中常见初始残余应力对组合梁的影响机理。结果表明:残余应力主要是通过影响钢梁的截面模量,进而对钢梁的截面抗弯刚度产生影响,在升温后期或当钢梁开始进入塑性状态时,残余应力的影响逐渐减小。残余应力在钢梁腹板上的分布能较为明显的影响组合梁的承载能力,分布形式不同影响效果也不同。残余应力主要影响了组合梁中钢梁的截面刚度,进而也影响了组合梁的挠度幅度、曲率分布、中和轴高度以及拉索内力变化。

In order to study the influence of residual stresses on the mechanical performance of a prestressed simply supported composite beam embedded in the steel beam under fire,a model with the geometric nonlinearity and material properties are built by using ABAQUS software.A nonlinear finite element model for calculating the structural response behavior of composite beams at elevated temperatures using the thermos-mechanical coupling method.This paper investigates the response of section temperature,overall deflection and mid-span deflection,mid-span section stress distribution,cable stress and plastic deformation,overall curvature and mid-span curvature at high temperature,and explores engineering application.The results show that the residual stress mainly affects the flexural stiffness of the steel beam by affecting the section modulus of steel beam.In the later stage of heating or when the steel beam begins to enter a plastic stage,the influence of residual stress gradually decreases.The distribution of residual stress on the beam web can obviously affect the bearing capacity of the composite beam,and different distribution forms have different effects.Residual stress mainly affects the section stiffness of the steel beam in the composite beam,and then also affects the deflection amplitude,curvature distribution,neutral axis height and the change of the internal force of cable.