不同受火方式后混凝土短柱的抗震性能  

Post-fire seismic behaviors of concrete stub columns in different fire exposure cases

作　　者：徐玉野[1] 陈雅熙 鄢豹 郑涌林[1] 罗漪[1] XU Yuye;CHEN Yaxi;YAN Bao;ZHENG Yonglin;LUO Yi(College of Civil Engineering,Huaqiao University,Xiamen 361021,China)

机构地区：[1]华侨大学土木工程学院,福建厦门361021

出　　处：《振动与冲击》2020年第18期11-19,共9页Journal of Vibration and Shock

基　　金：国家自然科学基金(51578255,51778247);福建省自然科学基金(2017J01093)。

摘　　要：通过对5个混凝土短柱的拟静力试验,其中1个为未受火短柱,1个为四面受火后短柱,2个为三面受火后短柱,1个为邻面受火后短柱,考察受火方式和水平力加载方向对短柱的破坏形态、受剪承载力、刚度、延性和滞回耗能等特性的影响情况。建立有限元模型对短柱进行火灾全过程下温度场分布和灾后单向推覆过程的数值模拟,并利用试验结果验证数值模型的有效性。结果表明:随混凝土柱受火面数量的减少,截面中心处的最高过火温度、短柱的受剪承载力和耗能能力的损伤显著减少。受火120 min后,四面、两种三面、邻面受火后混凝土短柱截面形心处最高过火温度分别为341℃、267℃和251℃、191℃。与未受火短柱相比,四面、两种三面、邻面受火120 min后混凝土短柱的受剪承载力分别降低了41.2%、18.6%和18.8%、6.6%,1/50位移角循环结束时短柱的累积滞回耗能分别降低了46.2%、27.6%和28.9%、12.4%。对于三面受火后混凝土短柱,水平力沿对称轴作用和垂直对称轴作用两种加载方向作用下抗震性能大致相同。建立的有限元模型能较好预测不同受火方式后截面的温度发展历程和灾后受剪承载力。Experimental investigations were carried out on reinforced concrete stub columns(RCSCs)subjected to quasi-static loading after being exposed to standard fire.The fire exposure cases chosen for study were:four faces exposure(1 specimen),three faces exposure(2 specimens),two adjacent faces exposure(1 specimen),and no face exposure to fire(1 specimen).The effects of the fire exposure case and horizontal loading direction on the failure pattern,shear strength,stiffness,ductility and hysteretic energy dissipation of the specimens were investigated.A finite element model was also developed to simulate the temperature distribution during fire exposure period and the behavior under post-fire push-over loading.The developed FE model was validated by experimental test results.The results show that the decrease of the number of fire exposure faces leads to the decrease of the maximum sectional center temperature and the decrease of the declination in shear strength and hysteretic energy dissipation after a fire of 120 min.The maximum sectional center temperatures in the columns,after a fire of 120 min,were measured and are found to be 341℃,267℃and 251℃,191℃for the 4-face,two kinds of 3-face,and 2-adjacent-face fire exposure,respectively.Compared with the RCSC with no face fire exposure,the shear strength of the RCSCs after exposure of 4-face,two kinds of 3-face,and 2-adjacent-face decreases by 41.2%,18.6%and 18.8%,6.6%,while the accumulated hysteretic energy dissipation of the stub columns at the end of a 1/50 displacement angle cycle test decreases by 46.2%,27.6%and 28.9%,12.4%,respectively.For the RCSCs exposed to 3-face fire,the seismic performances of the columns subjected to horizontal load along the symmetrical axis and perpendicular to the symmetrical axis are found to be nearly the same.The proposed numerical model can predict the temperature development process in the section and the shear strength of the post-fire specimens in different exposure cases.

关 键 词：混凝土 短柱 抗震性能 火灾后 受火方式 

分 类 号：TU375[建筑科学—结构工程] TU317