2.1.1 For the combined load cases, as defined in Pt 4, Ch 3, 4.3 Load combinations, the maximum permissible stresses of steel
structural members are to be based on factors of safety indicated in Table 5.2.1 Factors of safety for the
combined load cases.
Table 5.2.1 Factors of safety for the
combined load cases
Permissible stresses for:
|
Load case
(a)
|
Load case
(b)
|
Load case
(c)
|
Load case
(d)
|
Shear
(based on the tensile yield
stress)
|
2.5
|
1.89
|
1.89
|
1.72
|
Shear buckling
(based on the shear
buckling stress)
|
1.67
|
1.25
|
1.25
|
1.0
|
Tension and bending
(based on the tensile
yield stress)
|
1.67
|
1.25
|
1.25
|
1.0
|
Compression
(based on the lesser of the
least bucking stress or the yield stress)
|
1.67
|
1.25
|
1.25
|
1.0
|
Combined “comparative” stress
(based on
the tensile yield stress)
|
1.43
|
1.11
|
1.11
|
1.0
|
2.1.2 For plated structures, the combined ‘comparative’ stress is to be
determined where necessary from the formula:
where
and
are the combined axial and bending stresses in the X and Y
directions respectively,
is the combined shear stress due to torsion and/or bending in the
X-Y plane.
2.1.3 When finite element methods are used to verify scantlings, special
consideration will be given to areas of the structure where localised peak stresses
occur.
2.1.4 Non linear and plastic design methods may be used for verifying the
local structure in load cases (c) and (d), as defined in Pt 4, Ch 3, 4.3 Load combinations. Local yielding and permanent deformation
can be accepted; however, the structural arrangements must prevent progressive
collapse.
2.1.8 Permissible stresses in materials other than steel are to be specially
considered.