Mean crack spacing modelling for RC tension elements

An approach for predicting the crack spacing of reinforced concrete tension elements is presented in this paper. Two well established methods, the mean strain and the stress transfer approaches (partial interaction) are combined through a newly proposed strain compliance principle. Through the assumption of a linear strain shape function governing the reinforcement strains in the stabilized cracking stage, the method enables the prediction of the mean crack spacing from the stress transfer approach. The strain compliance principle establishes the equality of the mean strains, estimated for a given loading level by a mean strain approach and the stress transfer approaches. The proposed approach requires a single data point, represented by a reinforcement ratio and bar diameter, that is denoted as a reference element and is further used to obtain the distance between cracks for any other tensile concrete element. A free-of-shrinkage tension stiffening law was employed for the evaluation of the mean reinforcement strains. A thorough investigation of this approach together with results for varying concrete compressive strengths, reinforcement ratio and bar diameters is presented. The new method was shown to give reasonably accurate results and most importantly, proposes a new way of investigating the cracking behavior of concrete elements.