锈蚀箍筋约束混凝土的受力性能劣化机制与本构关系模型研究

Due to the corrosive attack of environmental actions, stirrups of existing reinforced concrete (RC) structures often corrode during the service life. Corrosion of stirrup not only could decrease the confinement effectiveness of core concrete and promote the propagation of cracking within concrete, but also could reduce the effective confinement of longitudinal steel. As a result, corrosion of stirrup significantly affects the mechanical performance and constitutive model of confined concrete. However, current research works on confinement effectiveness, mechanical degradation mechanism and constitutive model of concrete confined with corroded stirrups are significant lack, which makes it difficult to conduct the analysis and evaluation of the mechanical performance of existing RC structures. .This proposed research program focuses on the investigation of the mechanical degradation mechanism and constitutive model for concrete confined with corroded stirrups. The main research contents include: to explore the non-uniform distribution profile of steel corrosion within concrete; to establish the quantitative relationship models for steel corrosion loss between stirrup and longitudinal steel as well as that between corner section and straight section of stirrup; to investigate the evolution law of effective confinement and mechanical degradation mechanism for concrete confined with corroded stirrups; to develop a practical constitutive model for concrete confined with corroded stirrups. The obtained results would be used as the basis for safety evaluation as well as design-making of maintenance and retrofit for existing RC structures.

受腐蚀性环境作用的影响，在役钢筋混凝土结构的箍筋往往发生锈蚀。箍筋锈蚀不仅会降低对核心混凝土的约束效应，促进混凝土内部裂缝的发展，同时也会降低对纵筋的有效约束，从而影响约束混凝土的受力性能，进而对锈蚀箍筋约束混凝土的本构关系产生较大影响。然而，目前有关锈蚀箍筋约束混凝土的约束效应和受力性能劣化机制的研究匮乏，而且缺乏锈蚀箍筋约束混凝土的实用本构关系模型，从而难以有效开展在役钢筋混凝土结构的力学分析。.鉴于此，本项目重点围绕锈蚀箍筋约束混凝土的受力性能劣化机制与本构关系模型开展研究，主要研究内容包括：揭示混凝土中钢筋的非均匀锈蚀分布形态，建立箍筋和纵筋的锈损量之间以及箍筋的角部和平直段的锈损量之间的定量关系模型，探讨锈蚀箍筋约束混凝土的约束效应演变规律与受力性能劣化机制，提出锈蚀箍筋约束混凝土的实用本构关系模型。研究成果可以为在役钢筋混凝土结构的安全性评估和维护加固决策等提供科学依据。

本项目重点围绕锈蚀箍筋约束混凝土的受力性能劣化机制与本构关系模型开展研究，提出了基于混凝土电阻率的钢筋腐蚀等级概率评估方法，研发了一种连续获取钢筋全角度锈蚀形态图像的装置，揭示了混凝土中钢筋的非均匀锈蚀分布形态，建立了箍筋和纵筋的锈损量之间以及箍筋的角部和平直段的锈损量之间的定量关系模型，提出了混凝土中钢筋空间锈蚀特征参数之间的定量关系模型，探讨了锈蚀箍筋约束混凝土的约束效应演变规律与受力性能劣化机制，建立了锈蚀箍筋约束混凝土的峰值应力、峰值点应变和极限应变的预测模型，提出了锈蚀箍筋约束混凝土的随机本构关系模型。发表学术论文26篇（其中被SCI收录10篇、EI收录9篇），获授权国家发明专利4项、实用新型专利2项，培养硕士生10名。研究成果可以为在役钢筋混凝土结构的安全性评估和维护加固决策等提供科学依据。