锈蚀RC框架柱性能劣化的模拟与评估

为研究钢筋的不均匀锈蚀对RC框架柱性能的影响。推导了钢筋锈蚀过程中混凝土裂缝扩展规律以及锈蚀产物沿钢筋环向的分布规律,建立了基于表观裂缝宽度的纵筋锈蚀程度评估模型。通过引入锈蚀影响系数提出了考虑不均匀锈蚀分布的锈蚀纵筋等效强度模型。基于已有试验结果分析了纵筋锈蚀和箍筋锈蚀的关系,建立了箍筋和纵筋锈蚀程度的关联模型。基于Mander的约束混凝土模型建立了锈蚀箍筋约束的混凝土模型。模型计算结果表明:钢筋锈蚀导致混凝土、钢筋强度显著降低,钢筋的不均匀锈蚀会对钢筋力学性能产生影响。基于OPENSEES平台和所提出的材料模型,建立了锈蚀RC框架柱的数值模型。根据已有试验资料,先后对本文所提出的纵筋锈蚀程度评估模型,箍筋和纵筋锈蚀程度关系模型,锈蚀箍筋约束混凝土模型,以及锈蚀RC柱的数值模型进行了验证。结果表明,本文模型具有较好的精度,锈蚀程度评估模型能够体现主要因素的影响,研究结果可用于既有混凝土结构的性能评估。

Modeling and evaluation of deterioration of corroded RC columns

To understand the influence of non-uniform corrosion on the performance of RC frame columns, the corrosion crack propagation and the distribution of corrosion products were studied. The evaluation model of the corrosion rate of longitudinal reinforcement based on the corrosion crack width was established. By introducing the corrosion influence coefficient, an equivalent strength model of corroded longitudinal reinforcement was proposed, considering non-uniform corrosion. Based on the existing test results, the relation between the corrosion rates of longitudinal reinforcement and stirrup was analyzed, and the correlation model of the corrosion rates of stirrup and longitudinal reinforcement was constructed. A concrete model confined by corroded stirrups was proposed based on the Mander model. Calculation results show that the corrosion of steel bars significantly decreased the strength of the concrete and the steel bars, and the non-uniform corrosion of the steel bars affected the mechanical properties of the steel bars. On the basis of OPENSEES and the proposed material model, a numerical model of corroded RC frame columns was established. Given the previous test data, the models proposed in this study were verified. Results show that the models achieved high accuracy, the evaluation model of corrosion rate could reflect the influence of involving factors, and the research results can be used to evaluate the performance of existing concrete structures.