The existing outbuildings in an old stable-block are to be

modified to provide facilities for a motor vehicle repair shop.

A cross-section of the intended new roof structure is shown in

Figure

Using the design data given, check the suitability of the

proposed new steel beam with respect to shear and bending.

Design Data:

Characteristic dead load including self-weight (based on the

plan area) 2.25 kN/m2

Characteristic imposed load (based on the plan area) 1.5

kN/m2

Span of beam between the centres of bearing 6.55 m

Conditions of restraint at supports:

Compression flange laterally restrained

Beam fully restrained against torsion

Both flanges are free to rotate on plan Assume that the

existing roof trusses and proposed new structure do not provide

lateral restraint to the compression flange.

The existing timber roof trusses and the new timber

beams are supported on the top flange of the beam but are

not considered to provide any lateral restraint to the

compression flange.

The plan area supported by the universal beam comprises

a width of 2.0 m from the existing structure and 2.44 m

Example

Monday, October 12, 2015 9:03 AM

Week 5-6 Page 1

The plan area supported by the universal beam comprises

a width of 2.0 m from the existing structure and 2.44 m

from the new one.

Existing

Plan area supported = (4.44 × 6.55) = 29.1 m2

Week 5-6 Page 2

Check the suitability of a 406 × 178 × 67 UB S 275

section

Section Properties:

D = 409.4 mm d = 360.4 mm B = 178.8 mm T = 14.3 mm

t = 8.8 mm b/T = 6.25 d/t = 41.0 x = 30.5 u = 0.88

Sx = 1350 × 103

mm3

Zx = 1190 × 103

mm3 ry = 39.9 mm

Flange thickness T < 16 mm ∴ py = 275 N/mm2

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