FRCM Configurations for Seismic Strengthening of RC Exterior Joints: A Parametric Finite Element Study

Fiber Reinforced Cementitious Matrix (FRCM) has emerged as an effective retrofitting technique for reinforced concrete (RC) structures, particularly in enhancing the seismic performance of beam-column joints. This study presents a comprehensive investigation of carbon-FRCM retrofit configurations for exterior RC beam-column joints through experimental testing and numerical analysis. Initially, full-scale exterior RC beam-column joints were subjected to cyclic displacement-controlled loading up to 85% of their capacity to simulate seismic damage, subsequently retrofitted with carbon-FRCM, and tested to failure. A three-dimensional finite element model was developed using DIANA 10.5 software and validated against the experimental results, demonstrating good correlation in load-displacement response, energy dissipation characteristics, and failure mechanisms. The validated model was then employed to evaluate three distinct FRCM configurations: Scheme 1 with extended beam coverage, Scheme 2 with extended column coverage, and Scheme 3 with combined coverage. The numerical analysis revealed that while retrofitting schemes did not significantly influence joint strength capacity, strategic application of FRCM to the more critical regions of the joint, identified through geometric and reinforcement constraints, proves more effective in enhancing energy dissipation capacity, providing an optimal approach for seismic performance enhancement of damaged RC joints.