Sectional design of r/c members using deformational model with inclined top branch of steel stress-strain relationship

Abstract

The paper presents the analysis of advanced cross-sectional design models of R/C flexural members using inclined top branch of stress-strain relationship for flexural reinforcing steel. The analysis was performed having considered more effective way to use realistic properties of ductility of flexural steel. Workflow is based on a basic assumptions described in the Eurocode 2 and also in Model Code 2010. For concrete in compression the two models were considered: parabola-rectangle relationship and bi-linear stress-strain relation and for reinforcing steel - inclined and horizontal top branch models. There were derived and presented formulas for evaluation of cross-sectional parameters for the members with rectangular cross-section shape using the parabola-rectangle and bi-linear stress-strain relation for all the concrete classes and steel with inclined branch of strains. Adaptation in design of analytical formulas is very labour-consuming, therefore cross-sectional parameters for normal concrete and HSC were written using tabular coefficients and presented in the tables. As calculation examples of dimensioning of flexural beam are the areas of flexural reinforcement are compared for member with rectangular cross-section.