Corrosion-induced spalling of concrete cover and its effects on shear strength of RC beams

Abstract

Corrosion-induced spalling of cover concrete and its effects on shear strength of RC beams are numerical investigated in the present study. Firstly, a meso-scale model is employed to measure the development of corrosion-induced concrete spalling. The effects of corrosion, arrangement of the steel on concrete damage are clarified and a simplified model is proposed to quantify the damage. Following, a finite element model is developed to simulate the shear behavior. Corrosion induced section damage in concrete and steel, mechanical properties deterioration, and the bond degradation is considered into the model. The effects of concrete damage and bond degradation on shear behavior of corroded beams are discussed. Results show that corrosion-induced spalling of concrete cover initialed by the inclined cracks rooted from the corroded steel rebar and propagated diagonally toward to the surface, followed by the perpendicular crack propagated from the surface to corroded steel rebar. Spalling cracks propagated with the increase of corrosion loss. The propagation of inclined cracks, however, becomes slow and hard to cut through the cover as the perpendicular crack cut through the cover since the release of corrosion product along the perpendicular crack. Cover thickness, stirrup spacing and aggregate affects also significantly the spalling of concrete covers. The diameter of stirrup, however, affects slightly the final spalling of covers. Concrete damage and bond degradation would not significantly affect the shear behavior of RC beams unless the corrosion loss exceeds 15% and 6%~11%, respectively.