建筑结构学报2017，Vol.38Issue(5)：109-116,8.DOI:10.14006/j.jzjgxb.2017.05.014
Q690钢材高温后的力学性能试验研究
Experimental research on post-fire mechanical properties of Q690 steel
摘要
Abstract
By procedures of heating,cooling and tensile specimen test,an experimental study was carried out to investigate the post-fire (300 ℃ ≤ T ≤ 900 ℃) mechanical properties of high strength Q690 steel under two cooling methods,cooling in air and cooling in water.The post-fire appearance characteristics of high strength Q690 steel by different heating temperatures and cooling methods are different.High-temperature treatment and cooling methods have a great influence on the yield strength,ultimate strength and ultimate elongation of Q690 steel,but no obvious influence on elastic modulus,when heated to temperatures higher than 500 ℃.When the temperature is not higher than 700 ℃,there is a same trend for the post-fire strength and elongation of Q690 steel under the two cooling methods.The effect of cooling methods on the post-fire mechanical properties of Q690 steel appears between 700 ℃ to 800 ℃,and difference becomes bigger with the temperature increasing.When cooled in air,the post-fire strength of Q690 steel decreases with the temperature increasing but the ultimate elongation increases.On the contrary,when cooled in water,the post-fire yield and ultimate strength increase but ultimate elongation deceases with temperature increasing.The mechanical properties of Q690 steel after experiencing elevated temperatures were compared with Q235 and Q460 steel.It is found that steel grades have a significant influence on the post-fire mechanical properties of structural steel.When cooled in air,the higher strength steel (Q690) experiences greater loss of strength but becomes more ductile than the lower strength (Q235 and Q460) steel.Predictive equations were proposed for simple evaluation of post-fire material performance of Q690 steel.The results can be used to evaluate the bearing capacity of Q690 steel structures after fire.关键词
Q690钢材/冷却方式/受火试验/静力试验/力学性能/数学模型Key words
Q690 steel/cooling method/fire test/static test/mechanical property/predictive equation分类
建筑与水利引用本文复制引用
李国强,吕慧宝,张超..Q690钢材高温后的力学性能试验研究[J].建筑结构学报,2017,38(5):109-116,8.基金项目
科技部国家重点实验室基金项目(SLDRCE14-A-05),上海市高峰学科国际一流科研合作基金. （SLDRCE14-A-05）
