GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 Fig. 2. Models of the four alternatives to evaluate. Replacement of the column ( ): the first intervention is the removal of the severely damaged 1 column, replacing it with a new one identical to the original, therefore not providing a code adaption provisions. Rebar replacement ( ): recently, this method has been suggested for repairing columns that have 2 been damaged by corrosion and earthquakes. The external layer of concrete (depth 110 mm) is removed to allow the replacement of damaged longitudinal rebars for the entire height of the plastic hinge and to stop the corrosion of new steel rebars. The height of the intervention area is assumed to equal to the double of the length of the plastic hinge ( ). The repaired zone must 2 also be extended into the foundation in order to evenly distribute the tensions at the pier footing. The surface of the concrete core is treated in order to strengthen the bond between the old and new concrete pieces. New machined steel rebars are installed in place of the damaged longitudinal rebars. The installation is made with couplers that are attached to the back of the old rebars, and introducing new machined steel rebar segments aligned with the old rebars, welding them together. UHPC (Ultra-High Performance Concrete) is used for the concrete replacement which is extremely compact and has limited chloride penetration, increases the structure's durability and provides the required shear strength. CFRP jacketing ( ): the intervention is designed. The intervention aims at restoring the original 3 resistant moment , by removing the existing reinforcement bars and installing two types of CFRP: vertical (to restore the ); horizontal (to restore the shear resistance and ensure confinement).