Pseudo-dynamic tests on reinforced concrete bridges repaired and retrofitted after seismic damage

• Repairing and seismic upgrade of old rc bridge damaged by earthquake are discussed.
• Stainless steel bars, SCC and C-FRP improve durability, feasibility and reduce costs.
• Comparisons with original bridge behavior are carried out by pseudo-dynamic tests.
• Proposed intervention guarantees resistance recovery and improves seismic behavior.
• Smaller diameter of new stainless rebars and butt weld avoid rebar connection failure.

This research studies the seismic behavior of repaired and seismically upgraded reinforced concrete bridges that were severely damaged after an earthquake. These bridges were designed according to the previous Italian Code (1986) which did not include capacity design rules and proper construction details. Pseudo-dynamic tests were performed on these bridges by means of in-house test apparatus. Seismic actions similar to those used for undamaged bridges were applied. A repaired and retrofitted specimen in a 1:6 scale of the most stressed pier was tested physically in the lab while the rest of the bridge was simulated numerically. The scale factors of the pier specimens guarantee a global similitude to resisting shear and moment, confinement, buckling of longitudinal rebars and anchorage behaviour. The specimens were repaired through use of epoxy adhesive, stainless steel rebar parts, self-compacting concrete and strengthened with C-FRP wrapping. Finally the seismic behavior of the repaired and retrofitted bridge was compared to that of an Italian built bridge and to a bridge designed according to Eurocode 8 for the seismic design of bridges, both tested in previous researches. Conclusions on the overall behaviour were positive and recommendations for the improvement of some repair and retrofitting techniques are illustrated for future application and investigation.