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Steel Designers Manual - TheBestFriend.org

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This material is copyright - all rights reserved. Reproduced under licence from The <strong>Steel</strong> Construction Institute on 12/2/2007<br />

To buy a hardcopy version of this document call 01344 872775 or go to http://shop.steelbiz.<strong>org</strong>/<br />

<strong>Steel</strong> <strong>Designers</strong>' <strong>Manual</strong> - 6th Edition (2003)<br />

The<br />

<strong>Steel</strong> Construction<br />

Institute<br />

Silwood Park, Ascot, Berks SL5 7QN<br />

wu<br />

/M = 0.0625 li/a L2<br />

Worked examples 637<br />

Subject Chapter ref.<br />

DESIGN OF CONTINUOUS<br />

COMPOSITE BEAM<br />

Design code Made by RML Sheet no.<br />

BS 5950: Parts 1 & 3 Checked by TCC<br />

Use same design data as for simply-supported composite beams.<br />

Choose 406 ¥ 178 ¥ 60 kg/m UB grade S355 N.B. Section is plastic.<br />

(span/depth ratio = 22, and 12% weight saving).<br />

Construction condition<br />

Design load in construction condition<br />

wu = ( 16 . ¥ 05 . + 14 . ¥ 20 . ) ¥ 30 . + 060 . ¥ 14 . = 116 . kN/ m<br />

Check stability of bottom flange under worst combination of loading<br />

M = 0.0625 ¥ 11.6 ¥ 12 2<br />

Slenderness l = 12000/39.7 = 302<br />

= 104.4 kNm<br />

From SCI publication ‘<strong>Steel</strong>work Design: Guide to BS 5950:<br />

Part 1: Volume 1’ (page B5)<br />

u = 0.880 x = 33.8<br />

Assume top flange is laterally restrained by the decking. Use<br />

design formula for equivalent slenderness in BS 5950: Part 1<br />

(Annex G.2.4.1).<br />

l = n uv l where v =<br />

TB t t t<br />

a<br />

hs<br />

a l<br />

+<br />

h x<br />

Ê ˆ<br />

Ë ¯ +<br />

È 4<br />

Í<br />

Í<br />

Í 2 1<br />

1<br />

Ê ˆ<br />

ÎÍ<br />

20 Ë ¯<br />

and a = distance of restraint above shear centre of<br />

beam (= hs/2 in this case)<br />

hs = distance between shear centre of flanges<br />

s<br />

2 2<br />

˘<br />

˙<br />

˙<br />

˙<br />

˚˙<br />

05 .<br />

21<br />

1

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