Experimental investigation of preloaded RC columns strengthened with precambered steel plates under eccentric compression loading

Many existing reinforced concrete (RC) columns must be repaired or strengthened due to material deterioration, changes in usage or the implementation of new building design codes. In this paper, a new post-stressed method using precambered steel plates is proposed to strengthen existing RC columns. This approach can alleviate stress-lagging effects between the preloaded concrete core and steel jacketing and achieve higher axial strength and deformability. An experimental study was undertaken. Nine RC columns with different eccentricities, plate thicknesses and initial precamber displacements were tested under eccentric compression loads. According to the degrees of eccentricity, specimens were divided into three groups. In each group, one column without strengthening was tested to act as a control specimen, while the others were strengthened by precambered steel plates. Test results show that precambered steel plates were effective in increasing the axial strength and bending moment capacity of RC columns. Furthermore, by using precambered steel plates, the specimens had better post-yield deformation.