The present work investigates the application of precast elements in modern construction, especially the use of Composite Steel Trussed Concrete Beams (CSTCBs) through an analysis in a real building project located in Ciriè (TO), Italy. CSTCBs represent a hybrid structural solution that combines the benefits of steel and concrete, offering profits both in the design stage by enhancing the structural capacity and in terms of construction efficiency and speed. The study begins with an overview of precast concrete elements, their historical evolution and their role in current construction industry. Focus is given then to CSTCBs, describing their phased structural behaviour: in Phase I the steel truss acts as a self-supporting system, while in Phase II, after the hardening of cast in situ concrete, the complete section carries the loads.