点蚀圆钢管混凝土中长柱轴压性能研究

Axial Compression Performance of Slender Concrete-Filled Circular Steel Tubular Column with Pitting Corrosion Damage

点蚀对钢管混凝土柱服役期间的结构安全有显著影响。首先针对点蚀钢管混凝土柱的轴压性能开展了有限元分析,根据已有的试验结果建立并验证了有限元模型,在此基础上考虑点蚀坑几何尺寸以及蚀坑分布位置的随机性建立了带有随机点蚀的钢管混凝土柱精细化有限元模型。然后开展了有限元参数分析,分析了点蚀深度概率分布、点蚀体积损失率、钢材强度、混凝土强度和构件长细比对构件荷载-挠度曲线的影响。根据体积损失率等效的原则,建立了等效局部均匀腐蚀钢管混凝土柱有限元模型,对比了随机点蚀和均匀局部腐蚀对钢管混凝土柱轴压性能的影响。最后按照体积损失率等效的原则,基于三部国内钢管混凝土计算规程中的计算方法,对点蚀钢管混凝土柱轴压承载力进行计算并与有限元结果进行对比。结果表明:点蚀深度概率分布对构件轴压性能的影响可以忽略;相比于均匀腐蚀,点蚀对钢管混凝土承载力影响更大;使用GB 50936-2014《钢管混凝土结构设计规范》中的计算方法可较为准确且安全地预测点蚀钢管混凝土的轴压承载力,相比之下,GB 50936-2014中的方法可以在保证准确度的基础上有一定的安全性。

Localized pitting corrosion damage can cause an adverse impact on the safety of concrete-filled steel tubes(CFST).This paper conducted a numerical analysis of the axial compression performance of slender CFST with pitting corrosion damage.The failure phenomenon and load-deformation relationships from the existing tests were used to verify the numerical models.Then,the verified models were extended to take the random characteristics of corrosion pits in the aspect of distribution,dimensions,and locations into account.The influence of the degree of local volume loss,material strength,and slenderness ratio on the load-deflection curves was analyzed.According to the same degree of local volume loss,the CFST with equivalent thickness loss was established.The different influences of pitting corrosion and equivalent local defect on the ultimate strength were compared.Finally,based on the equivalent thickness loss,three methods based on the Chinese codes were put forward and verified against the results from the parametric analysis to calculate the axial compression performance of CFST column with pitting corrosion damage and compare with the result of FE analysis.The results show that the influence caused by different distributions of corrosion depth could be ignored.Compared with the equivalent local defect,the pitting corrosion can have a greater decrease in the ultimate strength of the slender CFST.According to the degree of local volume loss,the methods based on current codes GB 50936-2014,CECS 28∶2012,DBJ/T13-51-2020 could predict the ultimate strength of CFST with pitting corrosion damage,and the method based on GB 50936-2014 could provide a prediction with good accuracy and moderate consideration.