Numerical simulation of damaged reinforced concrete half-joint beams: towards appraisal and retrofitting

Abstract

Half-joint concrete beams are characterized by local reductions in the overall beam depth at the support and are ideal for structural connections. The beam joint region is however vulnerable for deterioration and for design/detailing shortcomings. This study explored the nonlinear numerical modelling potential of the behaviour of a series of impaired half-joint beams. The major defects were: diagonal-bar/ U-bar unavailability; shear reinforcement inadequacy; and reinforcement corrosion. The results highlighted the numerical simulation capabilities to capture global/local behaviours of the beam series. The load capacity prediction offset was in an impressive range of −16.7% to +1.5% and, in contrast, the predictions from the commonly used strut-and-tie model (STM) showed offsets in the extent of −39.2% to 16.9%. Subsequently, an experimental study was established using the FE model to explore the retrofitting potential of defective half-joint beams with a deep embedded (DE) technique. The strength enhancement was almost 30% and the internal load paths as well as the failure mode of the defective beam alternated favourably with the post-installation of the retrofitting element. Thus, the DE technique was identified to be an ideal option to retrofit impaired half-joint beams.