4 double tee design.pdf
TRANSCRIPT
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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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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
The Double Tee beam
Technical advantages
Applications
Details
Detailing interfaces in the structure
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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
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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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
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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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
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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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
Double tee floors can be cast with composite toppings
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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
-
ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
-
ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
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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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
-
ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
Debonding is possible
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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
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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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
A typical end detail
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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
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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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
Design approach for a
half joint end
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ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
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.
-
ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
-
ht
Prestressed ConcreteDr Howard Taylor FREng
Precast Concrete Consultant
www.htaylorfreng.co.uk
The Double Tee Beam
The Double Tee beam
Technical advantages
Applications
Details
Detailing interfaces in the structure