The seismic behavior of column–footing joints in reinforced concrete (RC) structures plays a critical role in ensuring structural stability under earthquake loading, especially near potential plastic hinge regions. This study aims to investigate the influence of different axial load levels and reinforcement configurations on the seismic performance of RC column–footing joints. Six specimens were cast using normal-strength concrete and subjected to reversed lateral cyclic loading. All specimens had identical dimensions, consisting of a 700 mm high column with a 120×120 mm cross-section placed on a 1000×300×200 mm footing. Two axial load levels were considered (40 and 70 kN), and the specimens were classified into three reinforcement configurations: (i) a conventional layout with stirrups and longitudinal bars, (ii) a modified design with additional longitudinal bars and connecting hoops, and (iii) a configuration with X-shaped diagonal reinforcement. Lateral loading was applied based on a processed ground motion from the 2003 Bam earthquake. Displacement was monitored using LVDTs, and performance was evaluated through skeleton curves reflecting changes in stiffness, strength, and ductility. Results showed that increasing the axial load reduced lateral resistance in reference specimens by 8.97%. The design with additional longitudinal bars and hoops maintained its strength (0.00% loss), while the X-shaped reinforcement exhibited a 5.56% strength gain. Under 40 kN axial load, the hoop-reinforced specimen improved by 13.49%, while the X-reinforced one slightly decreased by 1.46%. At 70 kN, both strengthened configurations showed substantial improvements of 24.67 and 14.27%, respectively. These findings highlight the effectiveness of longitudinal reinforcement under all axial conditions and the enhanced performance of diagonal X-bars under high axial loads, underscoring the importance of tailored reinforcement strategies for seismic resilience.
