Problem Data

Concrete Properties

Strength

Precast, release: 35 MPa
Precast, 28 days: 48 MPa
Cast-in-place topping, 28 days: 28MPa

Density, all concrete: 2403Kg/m³

Strand Properties

Strand Type: 1/2 - 270 K - Low relaxation

Two-point depressed pattern, depression point at 0.3L

Rebar Properties

fy: 413.685 MPa

Es: 207000 MPa

Prestress Loss Information

Calculation Method: AASHTO LFD
Hours to release:18=0.75 days
Relative humidity: 70%

Live Load

AASHTO LRFD HL-93
Metric Design Tandem - Metric Design Truck
Metric Design Lane - Metric Double Truck

Note: LRFD 2008 Interims requires effective width of slab over prestressed girders to be taken as the tributary width between the beams. While Precast/Prestressed Girder has been updated, this example/hand calculation has not been updated to include this particular provision.

Dead Load

Composite Dead Loads (Spans 1, 2, and 3)

On composite (DW):Weight of 50 mm future wearing surface (from curb-to-curb, 12.6 m) = 14.8428 kN/m
On composite (DC):2 barriers (4.378 kN/m each) = 8.756 kN/m

Precast Dead Loads (Spans 1, 2, 3, and Beams 1, 2, 3, 4)

(For exterior beams) 10 mm sacrificial/wearing surface = 0.7304 kN/m
(For interior beams) 10 mm sacrificial/wearing surface = 0.848 kN/m

Note: Starting with v9.00.00, you can simply enter deck thickness (sacrificial) as 10mm on the Geometry tab, and the program automatically computes the self weight of the sacrificial deck thickness. In this example, we will manually input the load due to sacrificial deck thickness and this new feature is not used.

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