Numerical Study on the Seismic Retrofitting of Reinforced Concrete Columns Using Rectified Steel Jackets

In this paper, application of rectified square steel jackets for improving the hysteretic behavior of reinforced concrete column has been investigated. Deficient performance of square steel jacket due to out of plane bulging in cross section under moderate and severe earthquake excitations and having an advantage of taking less space after retrofitting, strengthenin of square steel jacket in potential plastic hinge regions can be useful means for achieving appropriate performance of this type of steel jacket. In the present study, all of the analyses have been undertaken using ANSYS (version 10.0). In order to verify the accuracy and validity of the finite element modeling, the numerical results, obtained from nonlinear finite element analyses, have been compared with the available experimental data. Having verified the finite element modeling, a deficient RC column designed according to pre-1971 codes was selected and eleven specimens with different states of retrofitting details were used for reinforcement ofsquare steel jacket in potential plastic hinge regions. Also, the effects of increase in thickness of plate stiffeners, geometric shape of stiffeners and stiffened length of column have been investigated. The results of analyses indicate that energy dissipation and shear strength at rectified steel jacketed specimens significantly are improved by increasing the thickness of steel plate stiffeners until achieving maximum flexural strength of cross section and also stiffened height of column. However, geometric shape of stiffeners does not have a drastic effect on the hysteretic behavior of retrofitted column.