Efficiency of modelling corrosion-induced cover cracking in RC structures

Corrosion is one of the main causes of deterioration of reinforced concrete (RC) structures. Initially, it affects serviceability of a RC structure by causing excessive cracking of the cover concrete. A number of analytical models have been proposed to predict the time to corrosion-induced crack initiation. In this paper investigations on the applicability of the two main types of the analytical models based on solution of thickwalled uniform and double cylinders subjected to uniform internal pressure are described. FE analysis is employed for this purpose. Firstly, the influence of simplified formulation of the nonlinear behaviour of concrete is examined. The limits of applicability of the analytical models are established depending on c/d ratio (i.e., the ratio of the thickness of the concrete cover to the diameter of a reinforcing bar). Secondly, inability of the analytical models to account for actual boundary conditions of corroding reinforcing bars is studied. It is found that the influence of the boundary conditions on the predictive ability of the analytical models may be very significant. The FE analysis is also employed to investigate the influence of different types of concrete cover failure: cracking and delamination. The failure conditions in terms of ratios between certain geometrical parameters of a RC section have been established. The efficiency of the analytical models to describe different types of cover failure has been discussed.