A new shallow precast/prestressed concrete floor system for multi-story buildings in low seismic zones

A key economic value for multi-story office buildings, hotels, and similar structures is to have a shallow floor system that reduces the total building height and, consequently, reduces overall building cost. Additionally, minimizing the need for shear walls results in additional economy and flexibility in re-modelling. This paper presents the development of a new precast prestressed concrete framing system that achieves both goals for buildings up to six-story tall built in areas of low seismicity. The proposed system consists of precast hollow core slabs, shallow inverted tee beams, multi-story columns, and cast-in-place topping, which are the common components in conventional precast construction. The proposed system eliminates the need for permanent concrete column corbels, and achieves continuity in the inverted tee beam through column block-outs to improve the system’s resistance to lateral and gravity loads. Hollow-core slabs are also made continuous to minimize the need for shear walls in the hollow core direction. An experimental investigation was carried out to verify the theoretical capacities of the system components and to ensure that demand was met for the conditions being considered. Testing was performed using a full-scale specimen representing the area around an interior column. Test results indicated that the system is simple to construct and connection capacities can be adequately predicted using strain compatibility and shear friction theories. The design and construction of an office building in Lincoln, NE was presented as a successful implementation of the new system.