Open-slip Coupled Model Of Steel-to-Concrete Bond For Analysis Of Corroded RC Structures Subjected To Fatigue Loading

Corrosion of reinforcement in concrete damages the steel-to-concrete bond and affects the residual shear capacity of the RC structures. It is of great importance to research on the shear fatigue performance of the corroded structures such as bridges that suffer from the coupling effect of corrosion and fatigue damage. This research presents herein focuses on the development of steel-to-concrete bond models and their application for the analysis of corroded RC structures subjected to fatigue loading. The study includes:1. Based on the modeling concept of cracking shear transfer behavior, an open-slip coupled interface model is developed to simulate both pull out tests and axial tension tests. And this model is extended with the constitutive formulation of faituge damage on bond with the verification of both pull out tests under repeated loading.2. The axial tensile fatigue experiment of the corroded RC members is carried out, which discovers that the ultimate transverse crack number reduces as the increase of corrosion splitting crack width, i.e. the average transverse crack spacing will be enlarged while it is not influnced so much by the fatigue loading history.3. The open-slip coupled fatigue model is further extended with the formulation of the steel-rust-concrete interaction at interface and used for the simulation of the axial tensile tests incoporated with the corrosion pre-damage analytical approach. The possible contact damage between reinforcement and concrete is numerically captured, which could lead to the decrease of local bond performance. The experimental crack pattern is well simulated and verifies the applicability of the proposed model.4. Shear fatigue loading experiment on non-web RC beams after corrosion is carried out. Compared to the sound beam, a dramatic shortened fatigue life is observed for the corroded beam. The anchorage deterioration due to the bond damage by corrosion is deemed to be the source of failure and of much higher risk than the fatigue rupture of main reinforcement.5. The open-slip coupled models are applied to simulate the shear fatigue loading tests based on the corrosion pre-damage analytical approach. Analyses are also carried out to demonstrate the necessity of the open-slip coupled models and this analytical approach respectively. It is concluded that the corrosion cracking damage in concrete cannot be neglected in the analysis for the assessment of shear failure while the accurate prediction of residual shear capacity would require correct modeling of the contact damage at the interface. The residual shear capacity of the corroded beam subjected to fatigue loading can be well captured by the analysis with the proposed open-slip coupled models.