2. Steel Column Design

STRUCTURA AL STEELWORK & TIMBER DESIGN N - ECS328 STEEL COLU UMN DESIGN NOV13 – MAC14 M

C Clause

R Remarks Example E of Pinned Co olumn w/o Intermediatte Restrain The T column n shown in figure f below w is pin-end ded about both axes was design and a has no o intermedia ate restraintt. Column w n using S355 5 steel s and design comp pression forrce, NEd = 3 3500 kN

NEd = 3500 kN

1. 1 SELECTION OF SECTION Required R Area, A = NEdd / (fy / γMO ) 6.1 1 (1)

Partial P facto or for partic cular resista ance, γM Resistance R of cross-sec ctions whattever the c lass, γMO = 1 1.0

Ta able 3.1

Assume A the e nominal th hk. of flange e and web b is less than n 40mm and d 2 advance a UKB S355 to be used, .: yield streng gth, fy = 355 5N/mm .: . Required Gross Area a , A = NEd / (fy / γMO ) 3 =3500 = x 10 / (355 / 1.0 0) =98.60 = cm2 From F Table of Propertie es, select 356 x 368 x 1 129 UKC in SS355 steel 2 provided p 16 64 cm of Area A

   

1

356 x 368 x 129 UKC

MAT 

STRUCTURAL STEELWORK & TIMBER DESIGN - ECS328 STEEL COLUMN DESIGN NOV13 – MAC14

From section property tables, section properties for 356 x 368 x 129 UKC: Depth ,h Width, b Web thickness, tw Flange thickness, tf Root radius, r Depth between fillets, d Ratio for Local Buckling (flange), cf/tf Ratio for Local Buckling (web), cw/tw Radius of gyration y axis, iy Radius of gyration z axis, iz Torsional constant, IT Warping constant, Iw Area, A Modulus of elasticity, E Shear modulus, G

= 355.6 mm = 368.6 mm = 10.4 mm = 17.5 mm = 15.2 mm = 290.2 mm = 9.4 = 27.9 = 15.6 cm = 9.43 cm = 153 cm4 = 4.18 dm6 = 164 cm2 = 210 000 N/mm2 ≈ 81 000 N/mm2

2. CLASIFICATION OF SECTION Table 3.1

Take steel grade as S355 and tw = 10.4 mm < 40 mm .: fyw = 355 N/mm2

fyw = 355N/mm2

Web Table 5.2(1)

ε = 0.81 and cw/tw = 27.9 < 38ε .: Web section was Class 2

Table 3.1

Take steel grade as S355 and tf = 17.5 mm < 40 mm .: fyf = 355 N/mm2

fyf = 355 N/mm2

Flange Table 5.2(2)

ε = 0.81 and cf/tf = 9.4 < 14ε .: Flange section was Class 3 .: Section was Class 3 under compression

   

2 

Section was Class 3 under compression

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STRUCTURAL STEELWORK & TIMBER DESIGN - ECS328 STEEL COLUMN DESIGN NOV13 – MAC14

3.RESISTANCE OF CROSS- SECTION SUBJECT TO COMPRESSION 6.2.4

Compression

6.2.4(1)

The design value of the compression force NEd at each cross-section shall satisfy: NEd /Nc,Rd ≤ 1 (eq. 6.9)

6.2.4(2)

Nc,Rd = A fy / γMO (eq 6.10) = 164 x 102 (355) / 1.0 = 5,822kN

Nc,Rd = 5,822kN

NEd /Nc,Rd = 3,500kN/5,822kN = 0.6