Application of a closed-form solution for simulating bond between concrete and steel in service conditions

This study presents the results of numerical simulations of a series of bond tests using the well-known Russo model, which is the closed-form solution of the fundamental bond equation, based on a power-law function relating the local bond stress to the slip between the bar and the surrounding concrete. Pull-out tests carried on different concrete specimens with a single reinforcing bar were considered and the fitting of the experimental data allowed to work out the values of the main parameters of the model for usual values of concrete compressive strength. The model was extended to the case of pull-out tests where the yielding of the steel bar occurred. A further extension of the model was carried out to simulate the experimental results of the push-pull tests. Comparisons with results of different experimental tests allowed to verify the validity of the proposed analytical approach.