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Precast prestressed concrete beams, such as rectangular and inverted tee beam, currently used in residential and commercial buildings are deep, heavy, and limited to span-to-depth ratios of 15. The research proposes a composite structural steel and prestressed concrete beam that is shallow, light, easy to produce and erect, and able to achieve a span-to-depth ratio of 24. The proposed beam is designed to be used with precast columns, hollow-core planks, and a cast-in-place topping to create a moment-resisting floor system that minimizes the need for shear walls. The goal of this system is to eliminate as many of the limitations of precast concrete buildings as possible while remaining economically competitive. The developed beams consists of one half of a standard steel W-section, embedded into the top of a shallow rectangular prestressed concrete bottom flange, to create a composite section that supports hollow-core planks. Cast-in-place concrete is then used to fill the voids between the hollow-cores and composite beam and provide a leveled topping. A typical commercial building was analyzed and designed using the proposed beam under normal loading conditions. This design example indicated that the proposed system is economical, shallower, lighter, and more resistant to lateral loads than conventional precast concrete floor systems.
Adviser: George Morcous