Local buckling of thin-plate elements - The Behaviour and Design of Steel Structures to EC3 - page 149

Unstiffened web resistance.

k F = 2 + 6 × ( 300 + 0 )/ 1500 = 3.2 EC3-1-5 F6.1

F cr = 0.9 × 3.2 × 210000 × 10 3 / 1500 N = 403.2 kN

EC3-1-5 6.4(1)

e = 3.2 × 210000 × 10 2
2 × 355 × 1500

= 63.1 mm < 300 mm

= s s + c . EC3-1-5 6.5(3)

m 1 = ( 355 × 400 )/( 355 × 10 ) = 40 EC3-1-5 6.5(1)

m 2 = 0.02 × ( 1500 / 20 ) 2 = 112.5

EC3-1-5 6.5(1)

l y 6.11 = 63.1 + 20 × 40 / 2 + ( 63.1 / 20 ) 2 + 112.5

= 301.8 mm EC3-1-5 6.5(3)

l y 6.12 = 63.1 + 20 × √ 40 + 112.5
= 310.1 mm > 301.8 mm = l y 6.11 EC3-1-5 6.5(3)

l y = 301 8 mm EC3-1-5 6.5(3)

301.8 × 10 × 355
403.2 × 10 3

λ F = = 1.630 (> 0.5 ) EC3-1-5 6.4(1)

χ F = 0.5 / 1.630 = 0.307 EC3-1-5 6.4(1)
L eff = 0.307 × 301.8 = 92.6 mm EC3-1-5 6.4(1)
F Rd = 355 × 92.6 × 10 / 1.0 N EC3-1-5 6.2(1)
= 328.6 kN < 1400 kN, and so load bearing stiffeners are required.

Stiffener buckling resistance.

A eff , s = 2 × ( 16 × 100 ) + ( 2 × 15 × 0.814 × 10 + 16 ) × 10
= 5801 mm 2 EC3-1-5 F9.1

I eff , s = ( 2 × 100 + 10 ) 3 × 16 / 12 = 12.35 × 10 6 mm 4 EC3-1-5 F9.1

i eff , s = √ 12.35 × 10 6 / 5801 = 46.1 mm
λ 1 = 93.9 × 0.814 = 76.4

6.3.1.3(1)

L cr = 1.0 × 1500 mm = 1500 mm EC3-1-5 9.4(2)

λ = 1500 /( 46.1 × 76.4 ) = 0.426

6.3.1.3(1)

For buckling curve c, α = 0.49 EC3-1-5 9.4(2),T6.1
Φ = 0.5 ×[ 1 + 0.49 × ( 0.426 − 0.2 ) + 0.426 2 ]= 0.646 6.3.1.2(1)

χ = 1 / [ 0.646 + √ ( 0.646 2 − 0.426 2 ) ]= 0.884 6.3.1.2(1)

N b , Rd = 0.884 × 5801 × 355 / 1.0 N = 1820 kN > 1400 kN OK.

6.3.1.1(3)