The procedures of derivation of the tensile stress block from FE analysis results of concrete flexural members had been described in detail in Kwan et al and Ng et al Therefore, only the brief information is included here. From the FE analysis, the tensile stresses within uncracked and cracked sections at different stages of loading are obtained. The tension stress field is characterized by the variation of tensile stress with the theoretical tensile strain. The theoretical tensile strain is evaluated as the product of mean curvature φ and depth from neutral axis z, where the mean curvature is obtained by fitting the profile of deflected beam segment with a cubic polynomial and then differentiating the polynomial twice. For deriving the tensile stress block, the concept of mean tensile stress is introduced as the smoothened tensile stress of concrete with local fluctuations in the longitudinal direction eliminated. Across different sections, the mean tensile stress at any level of theoretical tensile strain is evaluated as the root-mean-square of the tensile stress values at the theoretical tensile strain level being considered.