D5.A.5.1 Members Subject to Axial Loads
The cross section capacity of tension only members is checked for ultimate limit state as given in Cl. 6.2.3 of the code.
Compression members will be checked for axial capacity of the cross section in addition to lateral buckling/stability. The cross section capacity will be checked as given in section 6.2.4 of the code.
Lateral stability of a pure compression member will be checked as per the method given in Cl. 6.3 of the code. The compression member stability will be verified as:
SGR
design input parameter (Refer to D5.A.6 Design Parameters). Even if you have
specified a custom yield strength (using the PY
parameter), the choice of
a buckling curve will be based on the value of SGR
parameter.Compression members that are susceptible to torsional or torsional flexural
buckling are checked for these modes of failure as well. The non-dimensional slenderness
¯λT
for these members is evaluated per Cl. 6.3.1.4 of the
EN 1993 code. The maximum slenderness among the flexural buckling slenderness, torsional
slenderness, and torsional-flexural slenderness is used to evaluate the reduction factor,
χ, for such members. The elastic torsional buckling load,
Ncr,T
, and the elastic torsional-flexural buckling load,
Ncr,TF
, are evaluated based on the method given in the
NCCI SN001a-EN-EU: Critical axial load for torsional and flexural torsional buckling
modes
(unless otherwise specified by a particular National Annex). The effective
length for the members can be controlled using the KZ
,
KY
, LZ
, and LY
parameters. If these
parameters are specified, the effective length will be calculated as
KZ
×LZ
for length about the Z-Z axis and
KY
×LY
for length about the Y-Y axis. By default, the
effective length will be taken as the member length.
EN 1993-1-1:2005 does not specifically deal with single angle, double angles, double channels, or Tee sections and does not provide a method to evaluate the slenderness of such members. In these cases, the EC3 (EN 1993) design module of STAAD.Pro uses the methods specified in BS 5950-1:2000 to calculate the slenderness of these members. Cl. 4.7.10 and Table 25 of BS 5950-1:2000 are used in the current version of the Eurocode 3 design module.