4 double tee design.pdf

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Prestressed ConcreteDr Howard Taylor FREng

Precast Concrete Consultant

www.htaylorfreng.co.uk

The Double Tee Beam

The Double Tee Beam

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The Double Tee Beam

The Double Tee beam

Technical advantages

Applications

Details

Detailing interfaces in the structure

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The Double Tee Beam

The double tee section Double Tees usually are provided in a range of depths from 300mmto 800mm

The 600mm Double Tee can carry 2.5 kN/m2 car park loading to 16m. In countries where car park loading

is taken as 3kN/m2 and parking spans are up to 20m, a 700mm deep unit can be used

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The Double Tee Beam

Double Tees can be made to a 2.4m module or a 3m module to fit

into an architectural grid. The top flanges can be curtailed easily and

single tees can be cast

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The Double Tee Beam

Double Tees have an end cage of shear links and have a light mesh in the top table

scarfed (dapped) ends can be provided as can skewed units

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The Double Tee Beam

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The Double Tee Beam

Double tee floors can be cast with composite toppings

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The Double Tee Beam

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The Double Tee Beam

The Double Tee has a technical

advantage compared with symmetrical

sections because of the high centriod

of the section and the resulting

difference between Zupper and Zlower

For example a 2.4 m wide 600mm deep double tee typically carries car park loading over a span

of 16m. Its self weight is 7.34kN/m, Car park loading is 6kN/m

Zu = 54.53 mm3 x 106 Zl = 26.14 mm3 x 106 M = (7.34 + 6)162/8 = 426.88kNm

su = 436.88/54.53 = 8 N/mm2

sl = 426.88/26.14 = 16.33 N/mm2

Thus su is small where it is additive and sl is large where it is subtractive

su

sl

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The Double Tee Beam

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The Double Tee Beam

Debonding is possible

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The Double Tee Beam

Double Tees are usually connected

by welded shear connectors and a

welded end tie to the structural frame

is used to carry stability tie forces

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The Double Tee Beam

A typical end detail

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The Double Tee Beam

Simple supports or continuity are possible

Note that double tees are always erected on Neoprene bearing pads

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The Double Tee Beam

Design approach for a

half joint end

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The Double Tee Beam

Long and short units placed

next to each other, for example

at the top and bottom of car

park ramps should be packed

to minimise camber differences.

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The Double Tee Beam

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The Double Tee Beam

The Double Tee beam

Technical advantages

Applications

Details

Detailing interfaces in the structure

4 double tee design.pdf

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