摘要
为研究钢框架在火灾爆炸联合作用下的破坏倒塌机理,利用ANSYS/LSDYNA建立了5层2跨的钢框架有限元模型,采用隐式分析方法研究钢框架在火灾单独作用下的温度分布特征和结构响应,随后对综合考虑高温和高应变率效应的钢材本构模型进行有限元验证,在得到可靠结果的基础上,采用显式分析方法对钢框架进行单独爆炸分析和火灾爆炸联合作用分析,得到其在不同火灾燃烧时间不同爆炸条件下的局部破坏特征以及整体响应情况。研究结果表明:在火灾作用下,钢材的弹性模量和屈服强度会发生退化,柱因承受的荷载超过高温下极限承载力而发生破坏,中柱因其承受的荷载最大而率先发生屈曲;发生爆炸时,火灾燃烧时间越长,构件温度越高,钢框架越易发生倒塌;在相同温度下,腹板作为迎爆面比翼缘作为迎爆面对结构的损伤更大;在单室火灾下,边中柱处发生爆炸钢框架抗倒塌能力最弱,中柱处爆炸框架抗倒塌能力最强,角柱处爆炸框架抗倒塌能力介于两者之间;在相邻双室火灾和四室火灾下中柱发生爆炸,火室上方混凝土板会因下部的梁发生剪切破坏而塌落;对角双室火灾下中柱处发生爆炸,钢框架因中柱和边中柱相继失效而倒塌。
The collapse mechanism of steel frames under the combined action of fire and explosion was studied by establishing a finite element model of a 5-storey,2-span steel frame using ANSYS/LSDYNA.The temperature distribution characteristics and structural response of the steel frame under the single action of fire were analyzed using an implicit analysis method.Subsequently,the steel constitutive model considering the effect of high temperature and high strain rate was verified through finite element method.Based on reliable results,the explicit analysis method was used to analyze individual explosions as well as the combined action of fire and explosion on the steel frame,obtaining local failure characteristics and overall responses at different fire burning times and under explosion conditions.The results indicate that the elastic modulus and yield strength of steel will deteriorate when exposed to fire,leading to the destruction of the column if subjected to a load exceeding its ultimate bearing capacity at high temperatures.The longer the duration of the fire,the higher the temperature of the components,resulting in an increased susceptibility for collapse of the steel frame.Additionally,at equivalent temperatures,there is greater damage to web-facing surfaces compared to flange-facing surfaces when exposed to blast.In a single-room fire,the explosion occurs at the edge central column where the steel frame has the worst resistance to collapse,while at the central column the steel frame has the strongest resistance to collapse,and at the corner column,the steel frame's resistance to collapse is between the two.In adjacent double-room and four-room fires,an explosion occurs at the central column,causing the concrete slab above the fire room to collapse due to shear failure of the beams below.In a diagonal double-room fire,an explosion occurs at the central column,causing the steel frame to collapse as the central column and edge central column fail successively.
作者
田力
王剑飞
TIAN Li;WANG Jianfei(School of Civil Engineering,Tianjin University,Tianjin 300350,China;Key Laboratory of Coast Civil Structure Safety,Ministry of Education,Tianjin University,Tianjin 300350,China)
出处
《中南大学学报(自然科学版)》
北大核心
2025年第2期622-636,共15页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(51238007,51178310)。
关键词
火灾
爆炸
钢框架
有限元分析
连续倒塌
fire
blast
steel frame
finite element analysis
progressive collapse
