problem$2\mathrm{.}1?$What theoretical frameworks underpin the core principles of civil engineering? Explore key theories shaping the discipline's understanding and application, considering structural mechanics, material science, fluid dynamics, geotechnical engineering, and environmental considerations. Investigate classical theories such as Euler$-$Bernoulli beam theory or Mohr$-$Coulomb theory, elucidating their significance in analyzing and designing structures, foundations, and environmental systems. Additionally, delve into contemporary theories like finite element analysis or computational fluid dynamics, highlighting their role in enhancing efficiency, accuracy, and sustainability in civil engineering practices. Through this exploration, elucidate how theoretical foundations drive innovation, problem$-$solving, and advancement in the field of civil engineering.