Janos Gergely

In‐Situ Verification of Rehabilitation and Repair of Reinforced Concrete Bridge Bents under Simulated Seismic Loads

Three in-situ tests were performed on two bents of a reinforced concrete (RC) bridge under quasi-static cyclic loads. The bridge was built in 1963 and did not possess the necessary reinforcement details for ductile performance. The tests included an as-built bent, a bent rehabilitated with carbon fiber reinforced polymer (FRP) composite jackets, and a damaged bent repaired with epoxy injection and carbon FRP composite jackets. Two new concepts of strengthening bridge bents with FRP composites were implemented in this study. The first involves shear strengthening and confinement of a beam cap-column joint through an FRP composite “ankle-wrap.” The second is an FRP composite “U-strap” to improve the anchorage of column longitudinal steel reinforcement extending into the joint. FRP composite jackets were also implemented in the columns and beam cap. An additional rehabilitation measure was that of anchorage of the piles to the pile cap using epoxied high strength steel bars. The performance of the bent in the as-built condition and that of the rehabilitated and repaired bents is described in terms of strength, stiffness, displacement ductility, and energy dissipation.

Seismic retrofit of reinforced concrete beam-column T-joints in bridge piers with FRP composite jackets

The research described in this paper encompasses laboratory as well as in-situ testing of reinforced concrete beam-column joints and multicolumn bridge piers rehabilitated with fiber-reinforced polymer (FRP) composite jackets. Fourteen RC beam-column joint tests were performed and a design equation was developed which determines the thickness of the FRP composite jacket and the orientation of the fibers for maximum effectiveness in enhancing shear capacity and ductility. Several in-situ tests were conducted at the South Temple Bridge in Salt Lake City, which included a three-column bridge pier without an FRP composite seismic retrofit, a pier retrofitted with FRP composite jackets, and a pier retrofitted with FRP composite jackets and a reinforced concrete grade beam. The design of the seismic retrofit was based on rational criteria, which included the design of the foundation and column retrofit, and the design equation for retrofitting reinforced concrete beam-column joints, developed in the laboratory tests. The performance target for the seismic retrofit was a displacement ductility twice that of the pier without the FRP composite retrofit. The FRP composite jacket was able to strengthen the cap beam-column joints of the pier effectively and the displacement ductility was increased to the designed level.