Design of Column Pad Concrete Foundations Subjected to Uniform Pressure

This thesis investigates the structural behavior and design methodology of column pad foundations, with a focus on validating the commonly used assumption of a uniform contact pressure distribution between the foundation and the underlying soil. The study aims to identify under which conditions this assumption holds true and when it may lead to inaccurate or overly conservative design outcomes. By combining Tsytovich’s flexibility theory with finite element simulations in Abaqus, the study evaluates how soil stiffness, foundation geometry and height-to-width ratio affect pressure distribution. The results show that Tsytovich’s assumption is not valid for low-stiffness soils or slender foundations, where pressure variations can exceed 300%. However, when the foundation thickness reaches approximately 30% of its width, the pressure variation remains within Tsytovich’s acceptable range of ~13%, supporting the assumption of uniform distribution. Furthermore, punching appeared to be the most common failure mode when designing column pad foundations. The study also concluded that using a thickness of 150 mm for soil and 250 mm for rock provides good starting values for preliminary design. In addition, the thesis introduces a design approach for square pad foundations, including dimensioning tables and ultimate limit state (ULS) checks for bending, shear, punching and ground bearing pressure. Furthermore, the thesis also addresses concentrated load scenarios and includes a column load study in which eccentricity, construction tolerances and base plate design are taken into account. The methodology is based on Eurocode standards and considers typical Swedish soil types—clay, sand, gravel and rock. Based on these analyses, dimensioning tables and design charts are created to facilitate fast and reliable foundation design in routine engineering practice. The results help bridge the gap between geotechnical and structural engineering approaches.