The effect of concrete creep on the long-term tension-stiffening law and prediction of a time-dependent inertia moment of the cracked RC flexural cross-sections

Abstract

In the paper, a long-term stress-strain model is proposed for predicting the deformational response of the cracked reinforced concrete beams subjected to sustained bending. The linear and non-linear evolution creep strains is evaluated in the analytical manner by using an average stress-strain approach. The cracking and creep phenomena are coupled by two reologic elements connected in a series. In this way, the total strain of concrete prior to cracking is determined by a linear creep law accounting for the stress rate effect, while the post-cracking behavior is specified as a sum of elastic strain between cracks, creep and cracked concrete strain, defined by the descending branch of the stress-strain law. The smeared crack approach is adopted and, in turn, this law is associated with the tension stiffening phenomenon. The formulae accounting for the tension stiffening decay with time due to time-variable stress are proposed and applied in prediction of the inertia moment of the cracked RC flexural members along with the obtained results verification with the experimental data.