Serviceability model for concrete frames Part II: Stress - strain diagram for cracked flexural members

Abstract

This paper presents a general methodology to adjust the coefficients defining a constitutive law for tensioned concrete to simulate, under serviceability conditions, the behavior of cracked concrete members subjected to simple and combined bending (with axial compressive forces). Although experimental results could be used to attain the mentioned objective, in this work the models proposed by the CEB are utilized, in order to obtain more general conclusions not subjected to specific experiments. A numerical parametrical analysis is performed to determine the more significant variables influencing the Tension-Stiffening effect and a simplified closed- form solution is derived for rectangular sections. A systematic study has been made to verify the ability of the method to simulate long-term effects. The methodology can be implemented as an initial process in a general model of analysis like the one presented in Part I.