Average Crack Spacing of Overlay-Strengthened RC Beams

This research evaluates the average crack spacing of overlay-strengthened RC beams. Current equations in different structural codes for predicting the average crack spacing of RC beams with multilayered reinforcing bars have proved inapplicable to overlay-strengthened RC beams, although both types of beams are reinforced with multiple layers. We have developed a simple, practical analytical model that can predict the average crack spacing of this type of beam. We analyzed an overlay-strengthened beam element using equilibrium and compatibility equations to formulate the average stresses of concrete, overlay, and tension reinforcement. Then we made a series of comparisons among various types of beam elements, using the experimental investigations to verify the model’s validity and reliability. The proposed model performs satisfactorily against measured responses from the experimental database.