#solve Delve into the fundamental principles that underpin the design and analysis of reinforced concrete structures in civil engineering. Discuss the theoretical frameworks that guide the selection of materials, the calculation of load-bearing capacities, and the considerations for ensuring structural integrity and safety. How do engineers determine the appropriate mix of concrete and the placement of reinforcement bars to maximize strength and durability? Examine the roles of factors such as compressive and tensile strengths, modulus of elasticity, and thermal expansion in influencing design decisions. Additionally, consider the impact of modern advancements in materials science and engineering software on traditional design methodologies. How do these innovations challenge or enhance established theories and practices in the field of reinforced concrete structures?