Bond of corroded reinforcement. Analytical description of the bond-slip response

As maintenance and assessment of concrete structures become more and more important, a good understanding of the bond and anchorage behaviour of corroded reinforcement is essential. This master thesis aims to give practical recommendations how to consider the change in bond behaviour for corroded reinforcement by adjusting bond-slip curves for uncorroded reinforcement. Results from a parameter study done by finite element analyses were analysed to examine the influence of different parameters on the bond behaviour of corroded reinforcement. The parameter study covered different geometries, different bar diameters, different types of concrete and different levels of corrosion penetration. The results were used to develop a method that gives the bond-slip curve of corroded reinforcement if the bond-slip response of uncorroded reinforcement is known. This is done by shifting the bond-slip curve of uncorroded reinforcement along the slip-axis; thus it is possible to obtain the bond-slip response including the maximum bond stress for the corroded reinforcement. The shift along the slip axes is determined by the degree of corrosion. The method is based on the hypothesis that the bond stress is mainly determined by the radial stresses around the reinforcement bar. The method assumes that each geometry has a unique radial stress-radial deformation curve, and that the radial deformations caused by corrosion can be related to the radial deformations caused by slip. The method was also applied on the bond-slip model given in the CEB-FIP Model Code 1990 to extend its area of validity to corroded reinforcement. The method was shown to be valid for different loading sequences. It was further compared to test results available in literature. With the introduced method it is possible to estimate the influence of corrosion on the bond-slip response, including the bond strength and the dissipated energy.