Page 315 - Civil Engineering Formulas

CHAPTER 10
BRIDGE AND

SUSPENSION-

CABLE FORMULAS

SHEAR STRENGTH DESIGN FOR BRIDGES

Based on the American Association of State Highway and Transportation Offi-
cials (AASHTO) specifications for load-factor design (LFD), the shear capacity,
kip (kN), may be computed from

V u 0.58F y ht w C (10.1)

for flexural members with unstiffened webs with h/t 150 or for girders with
w
2
stiffened webs but a/h exceeding 3 or 67,600(h/t ) :
w
C 1.0 when h
t w
h
when 1.25
h/t w t w
45,000k when h
1.25
F y (h/t w ) 2 t w
2
For girders with transverse stiffeners and a/h less than 3 and 67,600(h/t ) , the
w
shear capacity is given by
V u 0.58F y dt w C 1 C 2 (10.2)
1.15 1 (a/h)
Stiffeners are required when the shear exceeds V .
u
Refer to Chap. 9, “Building and Structures Formulas,” for symbols used in
the preceding equations.

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