Flexural strengthening of bridge piers using FRP composites

The effectiveness of FRP jackets for increasing the shear capacity and the flexural ductility of reinforced concrete (RC) columns was demonstrated in many studies. However, for smaller axial loads, the contribution of FRP jackets to flexural strength is minimal. Using FRP sheets in the direction of a column with end anchorage to improve its flexural capacity at the base is not easily achieved. This paper reports on a research project aimed at upgrading the flexural capacity of RC piers using near-surface mounted (NSM) FRP rods. Flexural strengthening and testing to failure of the piers were carried out on a bridge that was scheduled for demolition during the Spring of 1999. Three of the four piers of the bridge were strengthened with different configurations using FRP rods and jackets. The flexural strengthening was achieved using NSM carbon FRP rods that were anchored into the footings. The piers were tested under static push/pull load cycles. An analytical model was developed to determine the net forces acting on a bridge pier at a given load level based on the measured response. Strengthening techniques, test results, modes of failure, and sample analytical results of tested bridge piers are described and the effectiveness of this technology is demonstrated.