Precast/Prestressed Girder Help

Problem Data

Concrete Properties

Strength

Precast, release: 4.5 ksi
Precast, 28 days: 5.5 ksi
Cast-in-place topping, 28 days: 5 ksi

Density, all concrete: 150 pcf

Strand Properties

Strand Type: 1/2 - 270 K - Low relaxation (E_s = 28,500 ksi)

Straight Pattern

Rebar Properties

Grade 60 rebar

Prestress Loss Information

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

Live Load

AASHTO LRFD HL-93

Dead Load

Composite Dead Load:

On Composite (DW): 3-inch bituminous wearing surface as Area Load (0.035 ksf)
On Composite (DC):2 barriers = 0.6 klf

Diaphragm Loads: 0.81 kips at 25, 50, and 75 ft