Ultra-high-performance fibre-reinforced concrete jacket for the repair and the seismic retrofitting of Italian and Chinese RC bridges

The seismic behavior of Chinese RC (Reinforced Concrete) bridge piers with insufficient seismic details, severely damaged after an earthquake and then repaired and retrofitted by rapid interventions is investigated. The proposed interventions are applied on the damaged steel rebar and concrete parts in plastic hinge zone to guarantee the proper plastic dissipation of the seismic energy and the necessary shear strength and ductility improvements. New longitudinal shaped rebars and concrete jackets are used to substitute the pier damaged parts. Two repair and retrofitting procedures are presented and applied on 1:6 scaled pier specimens designed on the base of Chinese codes [1]-[3]: the first one uses an self-compacting concrete to build the concrete jacket and carbon Fiber Reinforced Polymer (CFRP) wrapping to assure the seismic improvements; the second one uses an ultra-high performance fiber reinforced concrete (UHPFRC) with steel fiber to build the concrete jacket and to assure the seismic upgrading allowing time and cost saving. The results of the first experimental tests on 1:6 scaled pier specimens repaired and retrofitting by the two procedures, are compared and discussed