Beam-columns - The Behaviour and Design of Steel Structures to EC3 - page 330

7.7.2 Example 2 - checking the major axis in-plane
resistance

Problem. The 9 m long simply supported beam-column shown in Figure 7.19b
has a factored design axial compression force of 200 kN and a design concen-
trated load of 20 kN (which includes an allowance for self-weight) acting in the
major principal plane at mid-span. The beam-column is the 254 × 146 UB 37
of S275 steel shown in Figure 7.19a. The beam-column is continuously braced
against lateral deflections v and twist rotations φ . Check the adequacy of the
beam-column.

Simplified approach for cross-section resistance.

t f = 10.9 mm, f y = 275 N / mm 2 EN 10025-2

ε = ( 235 / 275 ) 0.5 = 0.924 T5.2
c f /( t f ε) = (( 146.4 − 6.3 − 2 × 7.6 )/ 2 )/( 10.9 × 0.924 ) = 6.20 < 9 T5.2

and the flange is Class 1.

c w = 256.0 − ( 2 × 10.9 ) − ( 2 × 7.6 ) = 219.0 mm.

The compression proportion of web is

h

2 − ( t f + r ) + 1

N Ed
t w f y

α = c w

2

256

2 × 200 × 10 3 2 − ( 10.9 + 7.6 ) + 1

= 219.0

6.3 × 275

= 0.76 > 0.5 T5.2

396 ε
13 α − 1

c w / t w = 219.0 / 6.3 = 34.8 < 41.3 = T5.2

and the web is Class 1.

M c , y , Rd = 275 × 483 × 10 3 / 1.0 Nmm = 132.8 kNm.

6.2.5(2)

M y , Ed = 20 × 9 / 4 = 45.0 kNm.
200 × 10 3

47.2 × 10 2 × 275 / 1.0 + 45.0 132.8 = 0.493 ≤ 1

6.2.1(7)

and the cross-section resistance is adequate.