Modeling Proposal for Exterior RC Beam-Column Joints Strengthened by Composite Materials

Damages exhibited by reinforced concrete (RC) buildings designed before the entry into force of the modern codes pointed out the paramount role of beam-column joints. In particular, the absence of transversal steel reinforcement, together with the poor attention to structural details, resulted the main responsible for exterior beam-column joints mostly vulnerable toward horizontal seismic actions. The studies available in current literature paid particular attention to the assessment of the seismic vulnerability of RC beam-column joints and, more recently, to the development of strengthening interventions based on the use of Fiber Composite Polymer materials (FRP). The present paper is part of a research activity carried out by the Authors and finalized to develop reliable numerical models able to simulate the response of RC beam-column joints subjected to monotonic loads. In particular, the model previously proposed by the Authors for the case of RC beam-column joints without transversal steel reinforcement, a configuration typical for the majority of existing RC buildings in Italy, is here extended to the case of RC beam-column joints strengthened by FRP. The model, implemented in the OpenSees computer code, is developed and assessed with reference to RC joint specimens found in scientific papers published in literature.