摘要
“9·11”事件发生后,火灾下钢结构倒塌研究得到了世界各国学者的广泛关注。钢材的物理、力学性能在高温下会显著降低,从而钢结构极易发生倒塌。因此,该文基于平面钢框架在单柱受火条件下的倒塌试验,应用大型商业有限元软件ABAQUS的显式动力分析模块,并采用梁单元对试验进行数值模拟,重点研究了钢材高温材性模型对火灾下钢框架结构倒塌模拟的影响,提出了适用于火灾下钢框架结构倒塌模拟的钢材高温应力-应变本构模型和热膨胀系数模型的建议。该文列举了常用的三种高温应力-应变本构模型,同时考虑应变率效应的影响,通过模拟结果与试验结果的差异对比,分析了各个模型应用于火灾下钢框架结构倒塌模拟的有效性。理想高温应力-应变本构模型,会导致临界温度与失效模式模拟不准确,应用存在一定局限性;EC3高温应力-应变本构模型可较为准确地模拟准静态失效模式,但对于动力失效模式的模拟存在一定局限性;因此,对于准静态失效模式倒塌模拟,建议采用EC3或改进的EC3高温应力-应变本构模型;对于动力失效模式的倒塌模拟,建议采用改进的EC3高温应力-应变本构模型,并采用应变率效应增大系数(DIF)的方法以考虑应变率效应的影响。此外,通过四种钢材热膨胀系数模型的对比,进一步研究了钢材“相位变换”现象对火灾下钢框架结构倒塌模拟的影响。结果表明,虽然欧洲规范EC3给出了精细的热膨胀系数模型,但采用GB 51249取值的计算结果与试验符合更好,建议采用中国规范GB 51249的相关规定。
After the 9·11 incident,the research on fire-induced collapse of steel structures has been receiving a widespread attention from scholars all around the world.The physical and mechanical properties of steel material can be significantly reduced at elevated temperatures,thusly steel structures are prone to collapse under fire.This paper is based on the collapse experiment of planar steel frames with one column heated.The explicit dynamic analysis module of ABAQUS is used for simulation and the experiment is simulated by a beam element.The influence of high-temperature material model of steel on the simulation of collapse of steel frame structures under fire is studied.Some suggestions about how to choose the suitable high-temperature constitutive model and thermal expansion coefficient model for the simulation of collapse of a steel frame structure under fire are proposed.Three kinds of high-temperature constitutive models considering the effect of strain rate are enumerated.By comparing the simulation results with the experimental results,the effectiveness of each model in the simulation of collapse of steel frame structures under fire is analyzed.Ideal high-temperature constitutive model will lead to an inaccurate simulation of a critical temperature and failure mode,and there are some limitations in its application;EC3 high-temperature constitutive model can accurately simulate the quasi-static failure modes,but cannot simulate the dynamic failure mode correctly.Therefore,it is suggested to adopt EC3 or the improved EC3 high-temperature constitutive model for the simulation of a quasi-static failure mode.For the simulation of a dynamic failure mode,the improved EC3 high-temperature constitutive model is recommended and Dynamic Increase Factor(DIF)is adopted to consider the effect of a strain rate.In addition,by comparing four kinds of models of thermal expansion coefficients,the effect of phase transformation of steel material on the simulation of collapse of steel frame structures under fire is further studied.Although EC3 has provided a detailed thermal expansion coefficient model,the model proposed by GB 51249 is recommended as it more closely fits test results.
作者
冯程远
李国强
蒋彬辉
FENG Cheng-yuan;LI Guo-qiang;JIANG Bin-hui(College of Civil Engineering,Tongji University,Shanghai 200092,China;State Key Laboratory for Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《工程力学》
EI
CSCD
北大核心
2019年第12期24-36,78,共14页
Engineering Mechanics
基金
国家自然科学基金项目(51878506)
关键词
结构工程
钢框架
倒塌数值模拟
火灾
高温应力-应变本构模型
热膨胀系数模型
structural engineering
steel frame
numerical simulation of collapse
fire
high-temperature constitutive model
thermal expansion coefficient model