Crack model for RC members based on compatibility of stress-transfer and mean-strain approaches

Abstract

The current study proposes a simple and mechanically sound analytical approach for crack analysis of reinforced concrete (RC) flexural members at the stage of stabilized cracking. The philosophy behind the proposed methodology is to establish mean spacing between the primary cracks through the compatibility of the stress transfer and mean strain approaches. The governing parameters of crack spacing are obtained by equating mean strains of the tension reinforcement defined by these approaches. The model assumes that a single RC block of a length of mean crack spacing represents the averaged deformation behavior of the cracked member. Based on the experimental evidence, reinforcement strain within the block is characterized by a strain profile consisting of straight lines representing zones with different bond characteristics. It was shown that crack spacing is mostly governed by four geometrical parameters given in the order of significance: section height, reinforcement ratio, bar diameter, and cover. A limited comparative analysis has demonstrated that the predictions of mean crack spacing by the proposed model agree well with the tests. Considerations are given to extend the proposed methodology to the analysis of maximum crack width.