A prestressed hollow core slab element studied in this thesis is a precast prestressedrnconcrete member with continuous voids provided to reduce weight and, therefore, cost and,rnas a side benefit, to use for concealed electrical or mechanical runs. Primarily used as floorrnor roof deck systems, hollow core slabs also have applications as wall panels, spandrelrnmembers and bridge deck units. This system of construction does not require form workrnand Propping during installation.rnPrecast, prestressed concrete floors offer significant advantages in many types ofrnbuilding construction. They offer design, time and cost advantages over other flooringrnmaterials and systems and are suitable for use with all structural systems, i.e. concrete,rnmasonry and steelrnIn our country precast prestressed concrete elements are not widely used forrnconstruction of most buildings. The conventional cast in-situ construction require lots ofrnformwork and construction time, and also the precast beam-slab system constructionrnrequire propping and construction time too which increases the total cost of a project.rnWhen precast prestressed hollow core slab elements are introduced in vast amount in thernconstruction of buildings, an economical construction could be achieved.rnThe economy of the generalized hollow core slab system is require a shortrnconstruction time compared to precast beam slab system and in the quantity of slabs thatrncan be produced at a given time with a minimum of labor required. Each slab on a givenrncasting line will have the same number of pre-stressing strands. Therefore, the greatestrnproduction efficiency is obtained by mixing slabs with the same reinforcing requirementsrnfrom several projects on a single production line. This implies that best efficiency for arnsingle project is obtained if slab requirements are repetitive.rnIn the present study, the advantages of prestressed hollow core slab elements, forrnconstruction of the floor slabs of four story building, is shown by making cost comparisonrnbetween the precast beam-slab system and pre-stressed hollow core slab system. For thisrniiirnpurpose, the same span length is chosen for the two slab systems. These elements arerndesigned for loads they should sustain when used in the construction of slabs.rnFinally cost comparison is made between the two systems of slab construction. Therncost comparison showed that the prestressed hollow core slab system