Wide Module Joists for Floor and Roof Decks


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Title: Wide Module Joists for Floor and Roof Decks

Author(s): L. E. Svab and W. T. Scott

Publication: Special Publication

Volume: 107


Appears on pages(s): 29-41

Keywords: concrete construction; concrete slabs; detailing; floors; formwork (construction); framing systems; joists; one-way slabs; thickness; reinforced concrete; reinforcing steels; roofs; structural design; Structural Research

Date: 6/1/1988

Cast-in-place concrete one-way ribbed slab decks are undergoing an evaluation. Slab thickness established by fire rating requirements and considerations of minimizing formwork labor and maximizing material economy have dictated a departure from the use of traditional 20 and 30 in. wide joist forms. Wider joist forms are being increasingly used to answer these considerations. Wide module joist systems generally have 6 to 8 in. wide ribs at 5 to 6 ft centers with 4-« in. top slabs and are supported by wide beams. The ribs are designed as T-beams rather than joists. ACI 318-83 design requirements are not pinpointed for the evolved slab/joist-beam system. Presented is an attempt to interpret and apply ACI 318-83 design requirements together with detailing and design considerations that are unique to this framing system.