Aluminium Design and Construction John Dwight

6.5.6). The first method becomes necessary when there are transverse
welds, and for bigger welds generally.
Care must be taken in dealing with a plate where the HAZ does not
penetrate all the way through the thickness (Figure 6.16). The factor k z
need only be applied to the softened part of the thickness in such a case.
9.2.3 Allowance for local buckling
When a column cross-section has been classed as slender, the effective
section of any slender element in it is assumed to be of the form shown
in Figure 7.4 (internal elements) or Figure 7.5 (outstands), using an effective
width model. The determination of the effective block-width (be1 or be0 )
is explained in Sections 7.2.3 and 7.2.4, or in Section 7.4.7 for reinforced
elements. Very slender outstands need special consideration (Section 9.5.4).
9.2.4 Allowance for holes
At any given cross-section, holes are generally allowed for by deducting
an amount dt per hole, where d is the hole diameter and t the plate
thickness. Exceptions are as follows:
1. For a hole in HAZ material, the deduction per hole need only be kzdt. 2. Filled holes can be ignored in compression members.
3. A hole in the ineffective region of a slender plate element in a
compression member can be ignored.
When a group of holes in a member is arranged in a staggered pattern,
as for example in the end connection to a tension member, there are
various possible paths along which tensile failure of the member might
occur and it may not be obvious which is critical. Thus in Figure 9.1(a) the
member might simply fail in mode A on a straight path through the first
Figure 9.1 Staggered holes in tension members.
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