Q550D高强度结构钢火灾升-降温过程力学性能研究  

Research on mechanical properties of Q550D high-strength structural steel during heating and cooling stages of fire

作　　者：蒋彬辉 王福鑫 王梦洁 李国强[2] JIANG Binhui;WANG Fuxin;WANG Mengjie;LI Guoqiang(School of Civil Engineering,Central South University,Changsha 410075,China;College of Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]同济大学土木工程学院,上海200092

出　　处：《建筑结构学报》2024年第12期160-169,共10页Journal of Building Structures

基　　金：国家自然科学基金项目(52378547);青年科学基金项目(51908560)。

摘　　要：为研究高强度结构钢的高温力学性能,采用稳态试验方法研究国产Q550D高强度结构钢在火灾升温和降温阶段的力学性能,包括其弹性模量、屈服强度、抗拉强度、极限应变和断后伸长率。定义了降温段影响系数,用以反映降温段与升温段高强钢力学性能的差异。研究结果表明:Q550D钢在火灾降温阶段的力学性能不仅与加载温度有关,还与峰值温度有关;当峰值温度在600℃以内时,Q550D钢在升温和降温阶段的力学性能差异相对较小,而随着峰值温度的进一步升高,特别是当峰值温度超过700℃时,降温段力学性能与升温段有明显差异,屈服强度和抗拉强度显著下降,极限应变显著增大。建立了Q550D钢降温段高温力学性能模型,得到Q550D钢在火灾降温段力学性能影响系数的计算公式拟合值与试验结果吻合较好。To study the mechanical properties of high-strength structural steel in fire,this paper investigated the mechanical properties of domestic Q550D high-strength structural steel during the fire heating and cooling stages,including the elastic modulus,yield strength,ultimate strength,ultimate strain,and elongation at break,by using the steady state test method.A cooling stage influence coefficient was adopted to reflect differences in the mechanical properties of steel between the cooling and heating stages.The results indicate that the mechanical properties of Q550D steel at the cooling stage are related to not only the test temperature but also the peak heating temperature.When the peak heating temperature is within 600℃,the difference in mechanical properties between the cooling and heating stages of Q550D steel is relatively small.However,as peak heating temperature further increases,especially when peak heating temperature exceeds 700℃,the significant differences appear on the mechanical properties between the cooling and heating stages,the yield strength and ultimate strength decreased significantly,and the ultimate strain increases significantly.Additionally,a high-temperature mechanical property model for high-strength steel during the cooling stage was established,and the proposed formula for calculating the mechanical property parameters of Q550D steel at the fire cooling stage was fitted well.

关 键 词：Q550D高强度结构钢 稳态试验 降温阶段 影响系数 高温力学性能模型 

分 类 号：TU391[建筑科学—结构工程] TU317.1