Innovative Analytical Approach For Evaluating The Performance Of Strengthened Edge RC Beam-Column Joints

Abstract

Beam-column joints (BCJs) are important in reinforced concrete (RC) constructions because they have a big effect on how loads are transferred and how stable the structure is, especially when it is under uniaxial monotonic loading.  Many older RC structures have poorly detailed joints, which makes them likely to break.  Using the Strut-and-Tie Model (STM), which has been verified by numerical modelling, this study looks at how strengthened and unstrengthened exterior BCJs behave.  Four samples: BCJ-1 (a control that met ACI 352-02), BCJ-2 (a joint that wasn't strong enough), BCJ-3 (a junction that was strengthened with CFRP), and BCJ-4 (a joint that was strengthened with a steel plate). Sta4CAD V14 and the Moment Distribution Method have been used to perform a sub-frame analysis and find the joint forces and inflection points. Results showed that CFRP and steel plate strengthening significantly enhanced joint performance in terms of shear strength, moment capacity, and strut width. CFRP sheets improved force transfer and stiffness due to effective confinement, while steel plates enhanced shear resistance and moment redistribution. CFRP provided superior energy dissipation, though steel plates offered advantages in durability and constructability. A finite element model employing STM principles was also used to evaluate strengthening efficiency. The findings highlight the critical impact of retrofit methods on joint behavior and offer practical insights for developing effective, economical strengthening strategies for RC joints under monotonic loads.