锈蚀钢筋的随机本构关系
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国家自然科学基金资助项目(51078268,51320105013)


Stochastic Model of Constitutive Relationship for Corroded Steel Bars
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    摘要:

    在已有锈蚀钢筋力学性能数据库的基础上,通过锈蚀钢筋拉伸试验和数据收集进行扩充.采用三维激光扫描技术获取锈蚀钢筋的三维实体模型,提取不同位置处横截面积并分析其纵向不均匀性.结果表明:锈蚀钢筋平均截面积与最小截面积之比R服从Gumbel极值分布,且随着钢筋锈蚀的发展,其横截面积分布愈发不均匀,R的均值和均方差均变大;随着钢筋锈蚀的发展,其名义屈服强度、极限强度和极限应变均有降低,屈服平台缩短,据此建立了锈蚀钢筋的确定性本构关系.统计分析发现,不同锈蚀率下的锈蚀钢筋力学性能服从正态分布,其变异系数随着锈蚀率的增加而增大,在此基础上建立了锈蚀钢筋力学性能退化的概率模型.最终把确定性的锈蚀钢筋应力应变模型发展为随机过程模型,为锈蚀钢筋混凝土构件时变可靠性评估奠定了基础.

    Abstract:

    The existing database for mechanical properties of corroded steel bars was extended by further tensile tests and collection of correlated data. Three dimensional (3D) geometric models of corroded steel bars were established by using a 3D laser scanner, and the area of any cross sections could be obtained. The ratio of the average to the minimum cross sectional areas of corroded steel bars, R, was adopted to quantify the longitudinal variation of the cross sectional area. It was found that R could be characterized by the Gumbel distribution. Both the location parameter and the scale parameter for the probability distribution of R increase linearly with increase in the corrosion degree. Tensile tests of corroded steel bars showed that the nominal yield strength, the nominal ultimate strength and the ultimate strain of the steel bar decreased, and the yield plateau became shorter and even disappeared with the development of reinforcement corrosion. Based on tests results, a deterministic model of stress strain relationship is introduced for corroded steel bars with different corrosion degrees. It is found by statistic analysis that mechanical properties of steel bars with various corrosion degrees keep normally distributed, while the coefficient of variation rises with the increase of corrosion degree. The probability distribution models of mechanical properties for uncorroded steel bars and the stochastic process models for the deterioration of mechanical properties due to corrosion are established. Consequently, the deterministic model of stress strain relationship for corroded steel bars is developed to a stochastic one, which can be used to model time dependent resistance and predict remaining service life of corrosion affected reinforced concrete structures more truly.

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张伟平,李崇凯,顾祥林,代红超.锈蚀钢筋的随机本构关系[J].建筑材料学报,2014,17(5):920-926

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  • 收稿日期:2013-06-08
  • 最后修改日期:2013-09-14
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  • 在线发布日期: 2014-10-31
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