What foundational theories in civil engineering underpin structural integrity, material properties, and design principles? Explore theories such as elasticity, plasticity, and structural analysis methods like finite element analysis. Investigate how these theories guide the design of buildings, bridges, and infrastructure, ensuring safety, functionality, and longevity. Delve into material science theories explaining the behavior of concrete, steel, and other construction materials under various loads and environmental conditions. How do these theories inform decision-making processes in civil engineering projects, from initial design to construction and maintenance? Additionally, consider the evolution of these theories and their contemporary applications in sustainable and resilient infrastructure development.