Steel Designers Manual - TheBestFriend.org

This material is copyright - all rights reserved. Reproduced under licence from The Steel Construction Institute on 12/2/2007
To buy a hardcopy version of this document call 01344 872775 or go to http://shop.steelbiz.org/
Steel Designers' Manual - 6th Edition (2003)
706 Welds and design for welding
a
I b a
3
2 Ê ˆ
yy = + 2
12 Ë 2¯
I00 = Ixx + Iyy
I
Distance r to extreme fibre (Fig. 24.13(b)):
1
r = a + b
2
Z
00
00
b + 3ab + 3ba
+ a
=
6
b + 3ab + 3ba
+ a
=
2 2 3 a + b
By similar reasoning to that given in Chapter 23 for bolts, fm, the force vector per
unit length from the moment, is
Rxr
fm
=
Z
2 2 ( )
00
fv, the shear, is assumed uniformly distributed around the weld group:
R
fv
=
2a+ 2b
The resultant force vector per unit length, fr, may be determined as shown in
Fig. 24.13(c) either graphically or trigonometrically:
tan a = ba /
fr = [ ( fm cosa + fv) + ( fm
sina)
The value fr can then be compared with the strength of the weld proposed from the
tables in the Appendix Capacities of fillet welds as appropriate.
24.7 Design strengths
24.7.1 General
3 2 2 3
3 2 2 3
2
( )
2 2
]
In fillet-welded joints which are subject to compression forces as shown in Fig. 24.14,
it should not be assumed, unless provision is made to ensure this, that the parent
metal surfaces are in bearing contact. In such cases the fillet weld should be designed
to carry the whole of the load.
Single-sided fillet welds should not be used in cases where there is a moment
about the longitudinal axis: see Fig. 24.15. Ideally they should not be used to transmit
tension.