IN-SITU TESTS OF AS-IS AND RETROFITTED RC BRIDGES WITH FRP COMPOSITES

The paper presents the results of three in-situ quasi-static tests performed on three reinforced concrete bridge multi-column bents. The bridge was built in 1963 but the design did not consider earthquake-induced forces or displacements since wind loads governed the design. The tests comprised the following: a test of Bent #4 with the deck removed; a test of Bent #5 with half the deck load; and a test of Bent #6 with half of the deck load and retrofitted with a carbon fiber reinforced polymer (FRP) composite seismic retrofit. All three bents were strengthened with a reinforced concrete grade beam connecting the pile caps under each of the columns. The lower bound of performance was exhibited by Bent #4, followed by Bent #5; Bent #6 performed exceptionally well as compared to the other two bridge bents, reaching a drift of 6%. The paper describes an analytical model of the bents including soil-structure interaction and the FRP composite seismic retrofit design. In addition, the paper describes the damage sequence, and a comparison of observed behavior and the behavior predicted by finite element models.