外包钢加固火灾后钢管混凝土叠合短柱轴压性能研究

STUDY ON AXIAL COMPRESSION PERFORMANCES OF CONCRETE-ENCASED CONCRETE-FILLED STEEL-TUBE STUB COLUMNS STRENGTHENED WITH EXTERNAL STEEL FRAMES AFTER EXPOSURE TO FIRE

在利用相关试验成果与有限元分析相印证的基础上,对常温下火灾后及外包钢加固火灾后钢管混凝土叠合短柱进行轴压性能研究,分析受火时间、缀板间距、外包钢厚度对试件承载力及刚度的影响。研究结果表明:外包钢加固火灾后钢管混凝土叠合短柱承载力及刚度提升幅度较大,甚至超过常温试件;随着受火时间的增加,试件承载力下降幅度经历了先增大后减小的过程,且外包钢对试件修复效果逐渐减弱;增大缀板间距,承载力逐渐降低,但降低幅度较小,而对试件刚度影响较大;增加外包钢厚度,承载力大幅度提高,刚度提高更显著。

Based on verification of fimite element analysis results with relevant experiment data,the axial compression properties of concrete-encased concrete-filled steel tubular(CFST)stub columns at room temperatures,post-fire and strengthened with cladding steel after exposure to fire were studied.The effects of fire exposure time,intervals of batten plate and thickness of cladding steel on the bearing capacity and axial stiffness of specimens were analyzed.The results showed that strengthened with cladding steel,the bearing capacity and stiffness of the specimens were obviously improved,even exceeding the ones of specimens at room temperature.Through parameter analysis,it was found that the degree of reduction for bearing capacity of specimens had experienced a process of increasing first and then decreasing,and the effects of repaired specimens with cladding steel were gradually weakened.The bearing capacity gradually decreased with the increase of intervals of batten plates,but the reduction was small,and the stiffness of specimens was evidently affected.Increasing the thickness of the clading steel could obviously improve the bearing capacity of specimens,and improve their stiffness more significantly.