Analytical model for predicting the response of oldtype columns rehabilitated with concrete jacketing under reversed cyclic loading

In the study presented herein, an analytical model for predicting the response of members with old-type detailing, rehabilitated with reinforced concrete (R/C) jacketing under reversed cyclic loading is developed. The analytical model considers that there is partial connection between the existing member (core of the retrofitted member) and its outer R/C shell, thus allowing relative slip of the two bodies. Slip takes place at the interface between the existing member and the jacket, mobilizing the shear resistance mechanisms, such as aggregate interlock, friction and dowel action. Constitutive models from the international literature are adopted to describe the mechanisms that resist relative sliding under cyclic shear reversals. Dual-section analysis is adopted to calculate the shear flow at the interface between the existing member and the jacket. An algorithm is developed to estimate the flexural response under cyclic loading taking into account slip at the interfaces. The proposed algorithm is utilized for the derivation of moment - curvature response histories of members tested in the laboratory, selected from a database compiled in the framework of the present study.