Investigation of the effect of retrofitting with concrete jacketing on increase of reliability in moment capacity of symetric reinforced concrete colums subjected to axial force and bending moment in one direction

In this study, the effect of the retrofitting with concrete jacketing on reliability of 12 different columns subjected to axial force and bending moment in one direction. Column cross-sections were 250x300 mm, 300x300 mm, 300x400 mm, 300x500 mm, 300x600 mm, 300x750 mm, 300x900 mm, 400x400 mm, 400x500 mm, 400x600 mm, 400x800 mm ve 500x500 mm. Thickness of concrete jacketing was assumed as 100 mm around the whole perimeters of columns. The reinforcement ratio was kept constant (about ρ=0.01) and symmetric reinforcement configuration were used before and after retrofitting. The axial force and eccentricity was calculated by N=0,5.Ac.fck and e=15mm+0,03.h respectively. 6 different characteristic strengths for concrete and one characteristic yield strength for reinforcement were taken in to account for all concrete columns before retrofitting. Characteristic concrete strength and characteristic yield strength of reinforcement were fck=30 MPa and fyk=420 MPa in concrete jackets respectively. Gauss and Log-Normal distributions were used in reliability computations in this study. In order to perform Monte Carlo Simulations, a computer program was coded in Visual Basic 2017 computer Language. 72 analyses, in which characteristic concrete strength in columns (before retrofitting) and column cross-sections were variables, were performed by using this program. In the results of analysis, increasing in bending moment capacities in columns and reliabilities of columns corresponding to varied external bending moments were obtained and presented by tables and graphics.