The Design of Modern Steel Bridges - TEDI

Stiffened Compression Flanges of Box and Plate Girders 179
Figure 6.8 Details of a design example of a stiffened compression flange.
The geometrical properties of this strut are:
Centroidal moment of inertia, Ix ¼ 64 840 298 mm 4
Area of cross-section ¼ 12 831 mm 2
Radius of gyration, r ¼ 71.09 mm
Maximum fibre distance to the top ¼ 50.54 mm
Maximum fibre distance to the bottom ¼ 174.46 mm.
Distance between stiffener centroid and girder neutral axis, h ¼ 897
50.54 ¼ 846.46 mm; e 1 ¼ eccentricity of applied loading ¼ r 2 =h ¼ 5.97 mm.
(a) Effective eccentricity for checking mid-span section of flange stiffener
¼ k1e1; when k1 ¼ 1 sa
þ 0:411 sa
sE
sa ¼ applied axial stress ¼ 145:6N=mm 2
sE ¼ Euler stress ¼ p2 Eð71:09Þ 2
k1 ¼ 0:8786
ð3000Þ 2
sE
2
¼ 1136 N=mm2
Effective eccentricity of applied loading ¼ 5.25 mm; e 2 ¼ amplitude of
initial imperfection ¼ 3000/625 ¼ 4.80 mm; 1 ¼ k 1e 1 þ e 2 ¼ 10.05 mm.
(i) For checking failure due to compression in flange plate
Z ¼
10:05 50:54
ð71:09Þ 2
The ultimate stress s su is given by
¼ 0:1005