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Re: Wide Shallow Beams

[Subject Prev][Subject Next][Thread Prev][Thread Next] Jeff,

This obviously depends on loading and exposure requirements. For a parking garage in a temperate climate, a good starting point would be,

Band    depth - L/25 to L/30 (L for longitudinal span)
Band width - L/4 to L/3 max at slab soffit (L for average transverse span) I would normally taper the sides of the band with a 1 to 1.5' taper for the L/25 or a 2' taper for the L/33 to save weight but that depends on formwork costs)

Slab depth - end spans - L/36 to L/40 where L is the distance from the centerline of the external column to the face of the 1st internal band, min 6"
                    - internal spans - L/40 to L/45 where L is the distance between the faces of the bands, min 6"

Drape slab tendons to high points at the faces of the bands at the slab soffit and run flat over band width at minimum top cover, except at end columns where they are draped to the centerline of the column and centroid of the slab (Dslab/2 from the top surface).

At 10:45 PM 5/03/02 -0800, you wrote:
I'm starting design on a wide-shallow (slab-beam) post-tensioned slab and can find no maximum span to depth recommendations for this type of system, only classical two way flat plate (L/45 - cont) and one way slab and beam (L/30 - cont).  The system will be limited by strength and deflection considerations but has anyone run across recommendations for initial design of this hybrid system?

Regards  Gil Brock
Prestressed Concrete Design Consultants Pty. Ltd. (ABN 99003351504)
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