STRENGTHENING OF CIRCULAR REINFORCED CONCRETE COLUMNS TO FOUNDATION CONNECTION WITH GFRP BARS AND CFRP SHEETS

Bridges play a significant role in developing the roads and accelerating the serviceability in normal and emergency situations. The corrosion problem of steel reinforcing bars in reinforced concrete columns of bridges in humid environments results in the early deterioration of these structures. Therefore, it is vital to use the efficient and cost-effective strengthening methods to increase the serviceability of these structures in critical situations. In this study, the strengthening of circular reinforced concrete column to foundation connections with fiber reinforced polymers is investigated. In the experimental part of the study, four specimens of column-foundation connections were cast and tested. One specimen was used as the control specimen without strengthening. Two other specimens were strengthened with GFRP reinforcing bars of different sizes. The fourth specimen was strengthened with both of GFRP reinforcing bars and CFRP sheets. These specimens were under constant axial compressive load and cyclic lateral displacement, simultaneously. Initial stiffness, energy dissipation capacity, lateral load capacity and ductility of the specimens are studied. In order to investigate the ability of the ABAQUS software, the experimental specimens were simulated in the aforementioned software. Test results show that the amount of lateral load capacity, initial stiffness, energy dissipation capacity and ductility increase significantly due to flexural strengthening of circular reinforced concrete column to foundation connections with GFRP bars. The highest increase in the amount of the aforementioned parameters is observed in the specimen strengthened with GFRP bars and CFRP sheets. The analytical results also show good agreement with the experimental results. The main difference between the analytical and experimental results is due to the simulation of pinching effect of the experimental results.