Concrete is one of the most used materials in the construction industry. In structural systems, the combination of concrete and steel reinforcement bars dives rise to reinforced concrete (RC), which is widely applied in the civil engineering field due to its adequate mechanical strength, durability, and fire resistance. Steel rebar reinforced structures are subjected to structural deterioration when subjected to extreme loadings such as earthquake, fire, impact loadings and cyclic loading, consequently reducing the expected life and performance of structures. To enhance the structural performance, the RC structures are usually retrofitted or strengthened. This book reviews design, performance and applications of reinforced concrete.