Structural Analysis of Reinforced Concrete Foundations Under Axial, Lateral, and Eccentric Loading for Bending and Shear Responses

Reinforced concrete foundations are subjected to axial, lateral, and eccentric loads that influence their bending and shear behavior and overall structural safety. This study presents a structural analysis of an isolated reinforced concrete foundation supporting a three-storey building under these three loading conditions. The methodology defines foundation load, bearing pressure, overturning moment, eccentric moment, flexural stress, shear stress, and utilization ratios, and applies them consistently to each loading case. Bending moment and shear force distributions along the normalized footing position are evaluated, and a normalized response index is used for comparison. Results show that eccentric loading produces the highest bending moment, flexural stress, and shear force, with a shear utilization ratio of 0.89. Axial and lateral loading reach 50.9 and 77.2 percent of the eccentric bending response, respectively. Eccentric loading is therefore the governing condition for foundation design. Controlling eccentricity during design and construction is essential to maintain safety margins.