Aluminium Design and Construction John Dwight

the use of limiting stresses taken from BS.8118. But, for fasteners, these
seem to be inconsistent with other codes, sometimes being very low,
and we therefore propose different values.
11.1.3 Joints in shear, fastener force arising
An accurate analysis of a joint in shear, allowing for the true behaviour of
the fasteners and the deformation of the connected plates, would be too
complex to use in normal design. Instead, the assumption is made that the
fasteners respond elastically, while the intervening plate is infinitely stiff,
enabling the shear force P – on any one fastener to be estimated as follows:
1. Concentric loading on a group of fasteners. When the transmitted force
P arising under factored loading acts through the centroid G of the
group (Figure 11.1(a)), it is assumed to be equally shared among all
the N fasteners:
(11.2)
2. Eccentric loading. When the line of action of P does not go through G
(Figure 11.1(b)), it must be resolved into a parallel force P through the
centroid and an in-plane moment M as shown. These produce parallel
and tangential force components (P – 1 , P– 2 ) on any given fastener, where:
(11.3)
(11.4)
The summation in equation (11.4) is for all the fasteners in the group,
and r the distance of thefastener from G. P – for the fastener considered
is found by combining P – 1 and P– 2 vectorially.
Figure 11.1 Joint in shear under (a) concentric and (b) eccentric loading.
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