针对以H型钢作为骨架的无筋混凝土结构,制作锈蚀率分别为0%、5%、10%、15%和20%的H型钢混凝土试件,开展推出试验,分析不同锈蚀程度下H型钢-混凝土界面的黏结应力-滑移关系,并提出一种通过测试混凝土表面的压缩位移获得钢-混凝土界面黏结应力分布的试验方法。基于试验观察,提出化学黏结、微观机械黏结、宏观机械黏结和铁锈界面黏结四种微观机制,以解释锈蚀对H型钢混凝土黏结性能的影响。构建考虑锈蚀率影响的黏结应力-滑移本构关系模型,引入界面损伤参数,对不同锈蚀率下的界面损伤演化过程进行分析。结果表明： H型钢与混凝土界面的初始黏结刚度随着锈蚀率的增加而提高,但在达到峰值应力之后,界面刚度的下降速率随着锈蚀率的增加而加快；当H型钢锈蚀率较高(≥15%)时,界面黏结滑移曲线呈现双峰值特征,即先上升后下降,然后再次上升,最终趋于下降；随着锈蚀率的增加,化学黏结和微观机械黏结的作用逐渐增强,而宏观机械黏结和铁锈界面黏结的作用则逐渐减弱；所建立的考虑锈蚀率影响的黏结应力-滑移本构关系表达式能够较好地描述锈蚀H钢-混凝土界面黏结特性；尽管锈蚀率的增加会加速界面刚度的减退,但对试件破坏时损伤程度的影响较为有限。

For unreinforced concrete structures utilizing H-shaped steel as a skeletal framework, concrete specimens integrated with H-shaped steel were prepared to represent varying degrees of corrosion, specifically rates of 0%, 5%, 10%, 15%, and 20%. Push-out tests were conducted to analyze the bond stress-slip relationship between H-shaped steel and concrete under different corrosion levels at the interface. An experimental method is proposed to derive the distribution of bond stress across the steel-concrete interface by measuring the compressive displacement on the surface of the concrete. Based on the observations from the tests, four microscopic mechanisms were proposed: chemical bonding, microscopic mechanical bonding, macroscopic mechanical bonding, and rust interface bonding, to explain the impact of corrosion on the bond performance of H-shaped steel in concrete. A constitutive relationship was constructed, incorporating the effect of the corrosion rate on bond stress slip, and an interface damage parameter was introduced to analyze the evolution of interface damage under varying corrosion rates. The research results indicated that the initial bond stiffness at the H-shaped steel-concrete interface increases with the corrosion rate. However, after reaching peak stress, the rate of decline in interface stiffness accelerates with increased corrosion. Notably, at higher corrosion rates (≥15%), the bond-slip curve displays a dual-peak feature, first ascending, then descending, followed by another rise, and ultimately declining. As the corrosion rate increases, the roles of chemical bonding and microscopic mechanical bonding become more dominant, while the contributions of macroscopic mechanical bonding and rust interface bonding diminish. The developed constitutive relationship, validated through comparative analysis with existing models, accurately describes the bond characteristics at the corroded H-shaped steel-concrete interface. Although an increase in corrosion rate hastens the reduction of interface stiffness, its influence on the extent of damage observed upon specimen failure is relatively limited.

TU399

四川省自然科学基金 (2022NSFSC0430)