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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 />

Plastic moment resistance of steel section<br />

= 355 ¥ 1200 ¥ 10 3 ¥ 10 -6<br />

= 426 kNm > 360.9 kNm<br />

Worked examples 641<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 />

This exceeds the design moment. It may be shown that 42%<br />

redistribution of moment is adequate. Check moment resistance of<br />

composite section.<br />

Moment resistance of composite section<br />

Effective breadth of slab (for internal span)<br />

B e = 0.7 ¥ 12000/4 = 2100 mm � beam spacing<br />

(note 0.7 has been used for internal span, rather than 0.8 for external span)<br />

Resistance of slab in compression<br />

Rc = 045 . fcuBe( Ds - Dp)<br />

= 0. 45 ¥ 30 ¥ 2100 ¥ ( 130 -50)<br />

¥ 10<br />

= 2268 kN<br />

Resistance of steel section in tension<br />

R s = Ap y = 7650 ¥ 355 ¥ 10 -3<br />

= 2715 kN<br />

As R s > R c, plastic neutral axis lies in steel flange<br />

Plastic moment resistance of composite section<br />

M R D 2<br />

( Ds + Dp) È(<br />

Rs - Rc)<br />

T ˘<br />

pc = s + Rc -<br />

¥<br />

2 2<br />

Í<br />

Î R<br />

˙<br />

f 4˚<br />

where R f = 12.8 ¥ 177.9 ¥ 355 ¥ 10 -3<br />

= 808 kN<br />

-3<br />

21<br />

5

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