Double Tees

Double tee slabs are produced on long line casting beds, normally 100 m to 150 m long (300 ft to 450 ft). Bulkheads are placed to form the required double tee lengths for individual projects. Pretensioning strands and carbon steel reinforcement and connection hardware are placed in the form to suit individual slab requirements prior to placing the concrete.

Applications
Double tee slabs are available from CPCI members all across Canada. Double tee slabs can be used for most applications requiring a long span floor or roof system (10 m to 30+ m) and/or additional load carrying capability. Double tee slabs are resistant to moisture and corrosion. Parking garages, office buildings, commercial buildings, gymnasiums, pool roofs, food processing plants, paper mills, industrial buildings, and sewage and water treatment plants are all ideal applications. Slabs can be cantilevered at one or both ends for up to 4 times the slab depth. Consult your local CPCI member for specific design assistance with cantilevers.

Sizes
Double tee slabs are available in modular widths (typically 2400 mm, 3000 mm and 3660 mm nominal widths). Slab depths can vary from 500 mm to 1000 mm. Stem widths are sized to suit structural and fire rating requirements. Consult your local CPCI member for available sizes.

Prestressing
Double tee slabs are prestressed. This allows for longer spans, shallow depth and the ability to carry heavy loads. This also permits better space planning and a lower floor/floor height. Lengthening the span may be economical (fewer slabs to make and install). Maximum span/depth ratios of 40 are recommended for floors. The load capacity is a function of the double tee cross-section, the amount of prestressing provided and the location of the prestressing. CPCI member’s load tables will define the allowable live and dead loads that a given slab can safely support in addition to the slab self weight.

Structural Floor & Roof Systems
Double tee slabs, cast on smooth steel forms, have a finished underside. The smooth ceiling provided by a double tee slab may require only the caulking of the longitudinal joints. The underside of slabs can be specified as Standard Grade, Finish Grade B and Finish Grade A as described in CSA A23.4-05, Clause 26.

Bearing Supports for Double Tee Slabs
Double tee slabs can be supported on many types of supports designed to carry the required dead and live loads. Precast beams, precast walls, poured concrete beams and walls, masonry walls, insulated concrete forming system walls and structural steel beams are all suitable for use with double tee slabs as load bearing systems - consult your local CPCI member for details.

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