Cover cracking model in reinforced concrete structures subject to rebar corrosion

Abstract

A new cover cracking model is proposed for rebar corrosion. Rebar corrosion involves rust, which contributes to an expansive radial pressure at the concrete-steel interface and hoop tensile stresses in the surrounding concrete. Once the stress state exceeds a certain limit, anisotropic damage occurs. First, we establish an anisotropic damage model for concrete, which fully reflects the unilateral effect. Then an analytical model is proposed to calculate the displacement and the stress in a corroded re- inforced concrete (RC) structural member based on that anisotropic damage. In this study, a concrete-rust-steel composite model is considered as a circular cylindrical concrete cover and a coaxial, uniformly-corroded, steel rebar, where the steel rebar and the mechanical properties of rust can be fully taken into account. At the same time, the influences of the steel-concrete interface pores and the cracks in concrete on the rust expansion pressure value are modeled. Finally, some experiments are made for comparison with the analytical results and good agreement indicated the proposed model could be used to predict both the variation of strain fields in structures during the corrosion process and the cover cracking time.