Structural Concrete - Hassoun

922 Chapter 22 Prestressed Concrete Bridge Design
( )
w slab_int = γ c t s b eff_int =(0.15) 8
(8.5) =0.85 klf Self-weight of slab at interior girders
12
w haunch_int = γ c b top_flange t
( haunch )
=(0.15)(3.5) 1
Self-weight of haunch at interior girders
= 0.44 klf
12
)
w g_int = γ c A g =(0.15) = 0.743 klf Self-weight of interior girder
(
713
144
Typically, intermediate diaphragm should be provided for later stability. However, intermediate
diaphragm weight is ignored in calculations for simplicity.
w DC1_int = w slab_int + w haunch_int + w g_int = 0.85 + 0.044 + 0.793 = 1.636 klf
Uniform weight of dead loads at interior girder includes girder, deck, and haunch
where
γ c = 150 pcf
t s = 8 in.
t haunch = 1 in.
t eff_in = 8.5 ft
t top_flange = 3.5 ft
Unit weight of concrete
Thickness of deck
Thickness of haunch
Effective width of deck
Effective flange width
DC2: Dead load of structural components and attachment after girder hardened
w barrier = n [ ]
wbarrier_top + w
b
barrier_bottom
γ
n c b
g 2
barrier − (1.5ft− 4in.)
= 2 [ ( )]
1 + 1.417
4
4 (0.15) (2.67) −(1.5) = 0.205 klf
2
12
Weight of concrete barrier distributed equally to all girders. If there are fences or other attachment,
weight should be adjusted.
DW: Added dead loads and future utilities.
w DC2_int = w barier = 0.205 klf
γ AC_wearing = 35 pcf
w AC_wearing = γ AC_wearing (w bridge − 2w barrier_bottom )
= (0.035)[34.83 − 2(1.417)]
w AC_wearing = 1.12 klf
Assume 35 psf AC overlay
Weight of AC wearing
w DW_int = w AC_wearing
n g
= 1.12
4
= 0.28 klf Weight of AC wearing distributed
equally to all girders