Kinematics‐based model for shear capacity assessment of unreinforced interior beam–column joints

This study presents a kinematics‐based model for assessing the shear strength of reinforced concrete interior beam–column joints without transverse reinforcement. The proposed framework is built on first principles—kinematics, equilibrium, and constitutive relations—and explicitly models discrete cracks by introducing kinematic parameters such as crack width and crack length. The formulation also accounts for the bond‐slip behavior between concrete and reinforcement, providing distinct expressions for deformed and smooth reinforcing bars. The solution is obtained through an iterative procedure suitable for engineering applications, providing accurate predictions when compared to experimental results. The model is validated with 26 test specimens and compared with the joint strength provisions of the Italian Annex of Eurocode. The results show that the proposed approach significantly reduces both the conservatism and scatter of code‐based strength predictions, providing an effective and practical tool for accurately assessing the shear strength of interior joints to avoid unnecessary, costly, and disruptive retrofitting interventions.