Question $1$: Elaborate on the theoretical framework and principles behind the design and implementation of reinforced concrete structures in civil engineering. Discuss the critical factors that must be considered when selecting materials and designing for both tensile and compressive strengths. How do the concepts of load$-$bearing capacity, durability, and serviceability influence the decision$-$making process in the structural design phase? Additionally, explain the importance of understanding stress$-$strain relationships, load distribution, and failure mechanisms in the context of ensuring the long$-$term stability and safety of concrete structures.