Aluminium Design and Construction John Dwight

Table 9.4 Torsional buckling of certain standardized profiles: parameter values
Notes. 1. Refer to Figure 9.14 for section geometry.
2. Despite its asymmetry, the value of k for section S2 may be found accurately enough as in
Section 9.6.8(4) taking s as given above.
3. For the back-to-back angles it is assumed that the two components are separated by a distance
t (at least).
4. For the channel S4:
where � s =slenderness parameter for column buckling about ss, and
�, �=parameters to be calculated using the relevant formulae in Table
9.2. Simple values are given for X.
9.6.11 Torsional buckling of certain standardized sections
Figure 9.14 shows four section shapes that are standardized in Britain
(BS.1161), having been proposed in 1952 by M.Bridgewater and J.B.
Dwight (except for the tee), as efficient profiles with a good compromise
between flexural, torsional and local stability. Each comes in a range of
geometrically similar sizes, and Table 9.3 lists their section properties
(in terms of the thickness t).
Table 9.4 lists seven different shapes of strut section using these
profiles, for which the torsional buckling slenderness � can be readily
determined from expression (9.10), with � t read direct from the table,
while k is found as in 9.6.8(4) using X and s as listed in the table.
9.7 COMBINED AXIAL FORCE AND MOMENT
9.7.1 The problem
When a member has to carry simultaneous axial force P and moment
M, it is obviously important to allow for interaction between the two,
typical examples being eccentrically loaded axial members and ‘beamcolumns’.
Below we provide checks that cover failure of the cross-section
and overall buckling of the member. A simplified procedure is available
for checking simple angles, channels and tees connected to one side of
a gusset (Section 9.7.9).
Copyright 1999 by Taylor & Francis Group. All Rights Reserved.