Structural steel is steel construction material, a profile, formed with a specific shape or cross section and certain standards of chemical composition and mechanical properties. Casting is a manufacturing process by which a liquid material is usually poured into a mould, which contains a hollow cavity of the desired shape, and then allowed to solidify. This book reviews research in the fields of structural steel and castings including recent advances on the design of shear connections, research on multiaxial fatigue in structural steel connections, thermosetting polymer nanocomposites castings based on polyurethane and epoxy polymers and gas emission from moulds with synthetic additives during metal castings.