初始几何缺陷对钢梁内嵌式预应力组合梁抗火性能的影响  

Effect of initial geometric defects on fire resistance of steel beam embedded prestressed composite beams

作　　者：刘雨晨 郑志远 鄢吉虎 聂俊 LIU Yuchen;ZHENG Zhiyuan;YAN Jihu;NIE Jun(Infrastructure Development Office,Wuhan University of Technology,Wuhan 430070,China;China Construction Third Bureau Science and Technology Industry Development Co.,Ltd.,Wuhan 430100,China)

机构地区：[1]武汉理工大学基建处,武汉430070 [2]中建三局科创产业发展有限公司,武汉430100

出　　处：《建筑结构》2023年第3期80-86,共7页Building Structure

摘　　要：为研究初始几何缺陷对钢梁内嵌式预应力组合梁抗火性能的影响,建立了钢梁内嵌式预应力简支组合梁在高温下非线性升温过程受力行为的有限元模型。通过考察梁的破坏形式、跨中挠度、侧向位移、拉索张力以及梁的曲率等关键参数的变化,得到初始几何缺陷对该预应力组合梁抗火性能的影响机理。分析结果表明:对于内嵌钢梁的预应力简支组合梁,初始几何缺陷形式可分为跨中弯扭屈曲和腹板局部屈曲两种,其中跨中弯扭屈曲对该预应力组合梁的抗火性能有一定影响。初始几何缺陷越大,该预应力组合梁跨中挠度随温度升高而下降的速率越大,临界温度更低。由于预应力拉索会随着组合梁变形协调,因此初始几何缺陷越大,同一温度下拉索应力与塑性应变也将更大。在高温破坏时,梁加载点处曲率最大,其次是跨中区段。初始几何缺陷形式影响了梁沿纵向的曲率分布,在第一阶弯扭屈曲形式的初始几何缺陷影响下,梁跨中曲率增大,但整体曲率所有下降;在第四阶弯扭屈曲影响下,梁跨中曲率减小,但整体曲率有所增大。To investigate the effect of initial geometric defects on the fire resistance of steel beam embedded prestressed composite beams, a finite element model of the stress behavior of steel beam embedded prestressed simply-supported composite beams during nonlinear temperature rise at high temperature was established. The mechanism of the influence of initial geometric defects on the fire resistance of this prestressed composite beam was obtained by examining the changes of key parameters such as failure mode, mid-span deflection, lateral displacement, tensile tension and curvature of the beam. The analysis results show that for the prestressed simply-supported composite beam with embedded steel beams, the initial geometric defects can be divided into two forms: mid-span buckling and web local buckling, among which the mid-span buckling has a certain influence on the fire resistance performance of the prestressed composite beam. The larger the initial geometric defect is, the greater the rate of decrease of the spanwise deflection of this prestressed composite beam with the increase of temperature, and the lower the critical temperature is. Since the presstressed tensile will coordinate with the deformation of the composite beam, so the larger the initial geometric defect, the greater will be the tensile stress and plastic strain at the same temperature. At high temperature damage, the curvature is greatest at the beam loading point, followed by the mid-span section. The initial defect form affects the curvature distribution along the longitudinal direction of the beam. Under the influence of the initial geometric defects in the form of first-order bending and torsional buckling, the curvature in the span increases, but the overall curvature all decreases;under the influence of the fourth-order bending and torsional buckling, the curvature in the span decreases, but the overall curvature increases.

关 键 词：抗火性能 初始几何缺陷 预应力筋 钢梁内嵌式组合梁 有限元模拟 

分 类 号：TU394[建筑科学—结构工程]