Partially prestressed concrete beams are concrete beams reinforced with a combination of prestressed and non-prestressed reinforcement. They occupy the whole spectrum of reinforcing range between fully reinforced and fully prestressed concrete beams. Partially prestressed beams are more complex to design than either type for at least two major reasons: (a) From a behavioral viewpoint, they crack under a fraction of the specified live load; essentially, in the cracked state they act as reinforced concrete beams subjected to combined bending and compression, while in the untracked state they act as prestressed beams; and (b) From a design viewpoint, they have to accommodate simultaneously the concepts of ultimate strength design currently used in reinforced concrete, some concepts of working stress design mostly used in prestressed concrete and the concepts of service-ability, i.e., acceptable overall behavior under service loads.
