Cyclic Response of R / C Jacketed Columns Including Modelling of the Interface Behaviour

The research presented herein aims at the development of an analytical model for predicting the response of members with old-type detailing, strengthened with R/C jacketing under reversed cyclic loading. The analytical model introduces one degree of freedom between the existing member (core of the retrofitted member) and its outer R/C shell, thus allowing slip to take place at the interface between the existing member and the jacket. Shear resistance mechanisms, such as aggregate interlock, friction, and dowel action, are mobilized in response to slip. Constitutive models from the international literature are adopted to describe the mechanisms that resist 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. A calculation algorithm is developed to estimate the flexural response under cyclic loading taking into account slip at the interfaces. The validity of the proposed analytical model is assessed through comparison with experiments from the international literature.