$70\mathrm{.}90\mathrm{.}80.$#"What are the fundamental principles of structural analysis in civil engineering? How does the concept of equilibrium play a crucial role in understanding structural behavior? Explain the basic theories behind the design of reinforced concrete structures and the factors influencing their strength and stability. How do soil mechanics principles contribute to the foundation design process? Discuss the importance of fluid mechanics in hydraulic engineering and its applications in designing efficient water distribution systems.