BRIDGE AND SUSPENSION-CABLE FORMULAS 255whereM 1 smaller beam end moment; and M 2 largerbeam end moment.
The algebraic sign of M 1 /M 2 is positive for double-curvature bending and nega-
tive for single-curvature bending.
STIFFENERS ON BRIDGE GIRDERS
The minimum moment of inertia, in^4 (mm^4 ), of a transverse stiffener should be
at least
(10.36)where J2.5h^2 /a^20 2 0.5
hclear distance between flanges, in (mm)
a 0 actual stiffener spacing, in (mm)
tweb thickness, in (mm)
For paired stiffeners, the moment of inertia should be taken about the centerline
of the web; for single stiffeners, about the face in contact with the web.
The gross cross-sectional area of intermediate stiffeners should be at least
(10.37)
where"is the ratio of web-plate yield strength to stiffener-plate yield strength,
B1.0 for stiffener pairs, 1.8 for single angles, and 2.4 for single plates; and C
is defined in the earlier section, “Allowable-Stress Design for Bridge Columns.”
Vushould be computed from the previous section equations in “Shear Strength
Design for Bridges.”
The width of an intermediate transverse stiffener, plate, or outstanding leg
of an angle should be at least 2 in (50.8 mm), plus of the depth of the girder
and preferably not less than of the width of the flange. Minimum thickness is
of the width.
Longitudinal Stiffeners
These should be placed with the center of gravity of the fasteners h/5 from the
toe, or inner face, of the compression flange. Moment of inertia, in^4 (mm^4 ),
should be at least
(10.38)
wherea 0 actual distance between transverse stiffeners, in (mm); and tweb
thickness, in (mm).
Iht^3 2.4a^20
h^20.13
(^1)
16
(^1)
4
(^1)
30
A0.15BDtw(1C)
V
Vu 18 t^2 w "Ia 0 t^3 J