Local buckling of thin-plate elements - The Behaviour and Design of Steel Structures to EC3 - page 151

The resistance of the flanges to bending is

M f , Rd = ( 400 × 20 ) × ( 1540 − 20 ) × 345 / 1.0 Nmm
= 4195 kNm > 4000 kNm = M Ed EC3-1-5 5.4(1)

and so the flange resistance is not completely utilised in resisting the bending
moment.

2 × ( 15 ε t f ) + t w = 2 × ( 15 × 0.814 × 20 ) + 10 = 498 mm > 400 mm

EC3-1-5 5.4(1)

b f = 400 mm < 498 mm EC3-1-5 5.4(1)

0.25 + 1.6 × 400 × 20 2 × 345
10 × 1500 2 × 355

c = 1800 × = 469.9 mm

EC3-1-5 5.4(1)

2 4000

4195

V bf , Rd = 400 × 20 2 × 355
469.9 × 1.0

× 1 − N = 11 kN

EC3-1-5 5.4(1)

V bw , Rd + V bf , Rd = 1733 + 11 = 1744 kN.

EC3-1-5 5.2(1)

4.10 Unworked examples

4.10.1 Example 12 - elastic local buckling of a beam

DeterminetheelasticlocalbucklingmomentforthebeamshowninFigure4.32a.

4.10.2 Example 13 - elastic local buckling of a beam-column

Determine the elastic local buckling load for the beam-column shown in
Figure 4.32b when M / N = 20 mm.

4.10.3 Example 14 - section capacity of a welded box beam

Determine the section moment resistance for the welded box beam of S275 steel
shown in Figure 4.32c.

4.10.4 Example 15- designing a plate web girder

The overall depth of the laterally supported plate girder of S275 steel shown in
Figure 4.32d must not exceed 1800 mm. Design a constant section girder for the