Strengthening of eccentrically loaded reinforced concrete columns with fiber-reinforced polymer wrapping system: Experimental investigation and analytical modeling

This paper presents the results of experimental program and analytical modeling for performance evaluation of a fiber-reinforced polymer (FRP) wrapping system to upgrade eccentrically loaded reinforced concrete (RC) columns. A total of 12 RC columns with end corbels were tested. The test specimen had an overall length of 1,200 mm. Each end corbel had a cross section of 250×250 mm and a length of 350 mm. The specimen in the test region was 125×125 mm having a longitudinal steel ratio of 1.9%. Test parameters included confinement condition (no wrapping, full FRP wrapping, and partial FRP wrapping), and eccentricity-to-section height (eh) ratio (0.3, 0.43, 0.57, and 0.86). Research findings indicated that the strength gain caused by FRP wrapping decreased as eh was increased. Full FRP wrapping resulted in about 37% enhancement in compression strength at a nominal eh of 0.3, whereas only 3% strength gain was recorded at a nominal eh of 0.86. The compression strengths of the partially wrapped columns were on average 5% lower than those of the fully wrapped columns. A nonlinear, second-order analysis that accounts for the change in eccentricity caused by the lateral deformation was proposed to predict the columns strength. A comparison between analytical and experimental results of the present study in addition to data published in the literature demonstrated the accuracy and validity of the proposed analysis.