Civil Engineering Reference
In-Depth Information
6.1.1
Critical load
The critical loads for sway buckling when the building is under uniformly distributed
floor load are calculated from formulae (3.11):
where modifier
r
s
(0.834) is obtained from
Table 3.1
.
Torsion parameter
k
is obtained from formula (3.19):
With the above value of
k,
parameter
k
s
is obtained from (3.18) as
The critical load parameter (eigenvalue of pure torsional buckling) is obtained as a
function of
k
s
,
using
Table 3.2
in section 3.1:
α
=8.45.
The critical load for pure torsional buckling can now be calculated from formula (3.16):
Interaction among the basic modes may be taken into account by cubic equation (3.22).
(The fact that the system is monosymmetric is ignored in this worked example in order to
demonstrate how the effect of the interaction is calculated in the general case.) The
coefficients needed in the equation are obtained from formulae (3.23), (3.24) and (3.25):
