NONLINEAR RESPONSE OF COLUMNS STRENGTHENED BY NON-SYMMETRIC CONCRETE JACKETS UNDER ECCENTRIC VERTICAL LOADING

Abstract

The main objective of this research study is an in-depth investigation of the nonlinear structural behavior of concrete column jackets, with an emphasis on the case of non-symmetric jackets used to strengthen edge and corner under strength columns. A highly sophisticated analytical algorithm is developed, incorporating the nonlinear behavior of the concrete material, together with accurate modeling of the shear transfer mechanism at the contact surface. The relation between normal pressure and the developed shear stresses at the contact surface is studied in detail, and included in the developed analytical model. Finite element models are developed for actual lab specimens, and the analysis results are used to verify the developed model by comparison to available experimental results. A parametric study is performed on a number of actual building rectangular columns strengthened using non-symmetric concrete jackets. The developed analytical model is used to obtain results including the load fraction transferred from the existing column to the jacket for cases of corner, edge and interior columns. The results obtained are utilized to develop an in-depth understanding of the behavior of non-symmetrical column jackets, and provide insight into the behavior of these 3-sided, and 2-sided jackets, and their efficiency in strengthening existing columns. Useful conclusions, and recommendations are provided to assist designers in the field of this research.