Aluminium Design and Construction John Dwight

11.1.4 Joints in shear, fastener resistance
Failure at a fastener loaded in shear can occur either in the fastener
itself or else in the plate. The calculated resistance P – c per fastener should
be taken as the lower of two values found as in (1) and (2) below:
1. Shear failure of the fastener. This is a relatively sudden form of failure
with the fastener shearing into separate pieces. For a conventional
fastener the calculated resistance P – c is given by:
P – c =npsA (11.5)
where: p s =limiting stress in shear (table 11.1) =0.4f u
f u =minimum ultimate tensile stress of fastener material,
A=shank area (A 1 ) if failure plane is in shank,
=‘stress-area’ (A 2 ) if it is through the thread (table 11.2),
n=1 for single-shear joint, 2 for double-shear.
2. Bearing failure of the plate. This is a gradual event in which the fastener
steadily stretches the hole as the load builds up, there being no clear
instant at which failure can be said to have occurred. The calculated
resistance P – c is taken as follows:
P – c =kppdSt (11.6)
where: pp =limiting stress for plate in bearing (table 5.4)
=1.1(fop +fup ) …suggested,
fop , fup =0.2% proof and ultimate stresses for the plate material,
d=shank diameter d1 if bearing is on shank,
=mean diameter d2 if it is on the thread (table 11.2),
t=plate thickness,
k=factor depending on the joint geometry (see below),
Table 11.2 Standard ISO bolts (coarse thread)
Copyright 1999 by Taylor & Francis Group. All Rights Reserved.