Experimental validation of a low-invasive seismic retrofit solution for under-designed reinforced concrete frame system

Abstract

The feasibility and efficiency of a low-invasive seismic retrofit solution for existing reinforced concrete frame systems, designed before the introduction of modem seismic-oriented design codes in the mid 1970s are herein experimentally investigated. A diagonal metallic haunch system is introduced at the beam-column connections to protect the joint panel zone from extensive damage and brittle shear mechanism while inverting the hierarchy of strength within the beam-column subassemblies and forming a plastic hinge in the beam. The experimental results from cyclic quasistatic tests on 2/3 scaled beam-column subassemblies in as-built and retrofitted configurations provided validated the conceptual design and practical implementation of the overall retrofit strategy.