A welded steel plate girder consisting of two flange plates of 350 mm × 16 mm and a web plate of 1000 mm × 6 mm, requires

Transverse Stiffeners are provided to increase buckling resistance of the web due to shear, It is provided vertically along the span.

Horizontal Stiffener / Longitudinal Stiffener is designed to prevent web buckling due to bending compression.

End Bearing Stiffeners are provided at the supports & Load Bearing Stiffeners are provided at the points of concentrated loads.

Important Point:

if \(\frac{d}{{{t_W}}}\)< 67ϵ ⇒ unstiffened girder can be designed i.e. No girder required.

If 85 ϵ < \(\frac{d}{{{t_W}}}\)< 200 ϵ ⇒ Vertical stiffener (C1 and C2 ) may be provided.

If 200 ϵ < \(\frac{d}{{{t_W}}}\) < 250 ϵ ⇒ Vertical stiffener along with longitudinal stiffener at 0.2 d may be provided.

If 250 ϵ < \(\frac{d}{{{t_W}}}\) < 345 ϵ ⇒ Vertical stiffeners along with two longitudinal stiffeners at 0.2 d and 0.5 d respectively may be provided.

Calculation:

\(\frac{d}{{{t_w}}} = \frac{{1000}}{6} = 166.67\)

As \(\frac{d}{{{t_W}}} > 85\) and \(\frac{d}{{{t_w}}} < 200\)

Therefore, intermediate vertical stiffeners are to be provided.