碳纤维编织网增强ECC加固钢管混凝土短柱压弯承载力计算方法  

Eccentric bearing capacity of CFRP grid-reinforced ECC-strengthened concrete-filled steel tube columns

作　　者：颜宇鸿 卢亦焱[1] 李杉[1] 刘真真 YAN Yuhong;LU Yiyan;LI Shan;LIU Zhenzhen(School of Civil Engineering,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学土木建筑工程学院,湖北武汉430072

出　　处：《建筑结构学报》2023年第10期178-187,共10页Journal of Building Structures

基　　金：国家自然科学基金项目(51878520);中国博士后科学基金项目(2022M722480)。

摘　　要：为克服外贴FRP加固技术界面黏结耐久性差等缺点,提出碳纤维编织网增强ECC加固钢管混凝土技术,对已有的28根碳纤维编织网增强ECC加固钢管混凝土短柱(简称“加固柱”)和3根普通钢管混凝土短柱偏心受压试验结果进行分析,结果表明,未加固柱与加固柱破坏时均发生明显的弯曲变形,加固柱弯曲内侧碳纤维编织网断裂,加固层与内部钢管混凝土具备良好的协同工作性。在已有试验结果的基础上,考虑碳纤维编织网增强ECC加固层对原钢管混凝土柱中核心混凝土的额外约束作用,将加固柱轴力-弯矩曲线简化为四特征点模型,通过分析各特征点对应加固柱的应变与应力状态,计算对应的特征荷载及特征弯矩,建立加固柱轴力-弯矩相关曲线,计算结果具有一定安全储备。基于计算结果,引入考虑偏心率影响的偏心受压承载力折减系数,提出加固柱偏压承载力简化计算公式,计算值与试验值比值的均值为0.936。简化计算式形式简单方便,且计算误差较小,可为工程应用提供参考。To achieve the objective of rapid repair and strengthening of concrete-filled steel tubes(CFSTs),a novel technique involving the use of carbon fiber-reinforced polymer(CFRP)textile grid-reinforced engineered cementitious composites(ECCs)for strengthening CFSTs was proposed.By employing this technique,the poor interface bonding durability in the externally bonded FRP strengthening technique can be overcome.Twenty-eight CFRP grid-reinforced ECC-strengthened CFST columns(strengthened columns)and three un-strengthened CFST columns were tested under eccentric compression.The test results indicate that the failure mode of both the un-strengthened and strengthened columns subjected to eccentric loading is bending failure.For the strengthened columns,the carbon textiles were found to rupture on the inner side of the flexure.The deformation developing trend of the strengthening layer is consistent with that of the inner CFST.The mechanism of the additional confinement provided by the CFRP grid-reinforced ECC layer to the concrete core was defined.Based on the stress state of four characteristic points,a calculation model for predicting the N-M curve was then proposed.The predicted results exhibit high accuracy and included safety reserves.Finally,the strength reduction factor considering the influence of eccentricity was introduced,and a simplified formula for predicting the load-bearing capacities of the strengthened columns under eccentric loading was developed based on the calculated results.The average ratio of calculation to experimental results is 0.936.The simplified formula is easy to employ and had small errors,making it suitable for guiding engineering applications.

关 键 词：钢管混凝土短柱 碳纤维编织网 ECC 偏心受压试验 压弯承载力 

分 类 号：TU398.9[建筑科学—结构工程]