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Chapter Five LRFD code
The plate elements of the section will be classified as Compact/Non-Compact/Slender as
per the requirements of clause B5.1 and Table B5-1. These elements may also be
classified as Very Slender if they exceed the limitations set out in Table A-F1.1. If the
moments in the member are less than one ten thousandth of the yield moments the
section is considered to be in pure compression and will be classified accordingly. If an
element of the section is found to be slender, the stiffness reduction factors Q, Qa and Qs
will be determined as set out in Appendix B.
For tension checks, the capacity of the member is determined in accordance with section
D1.
For compression checks, the capacity of the member is firstly computed for the limit
states of flexural buckling about the major and minor axis is accordance with clause E2.
The capacity of the member for the limit state of flexural torsional-buckling is then
computed using clauses E3 and Appendix E. The compressive capacity of the member is
regarded as being the minimum capacity determined for these three limit states.
For bending checks the provisions of Appendix F1 are used. For each of the failure
modes, yielding, flange local buckling, web local buckling and lateral torsional buckling,
, p and r values are calculated. The values are based upon the section shape and the
axis of bending and are derived from Table A-F1.1. After the various  values have been
calculated they are then compared to find the appropriate equation to calculate M n, Equ.
A-F1-1 to 4. Each Mn value for the failure modes are then compared with the lowest
value governing.
Flange local bucking will only be considered for sections with non-compact flanges.
Similarly, web local buckling will only be considered for sections with non-compact
webs.
The design for shear is carried out in accordance with clause F2 using the provisions of
Appendix F2.2 when a stiffener spacing is specified. For plate girders with slender web
elements, the provisions of Appendix G3 will be utilised instead. No calculations are
conducted using Chapters K or J.
For the biaxial bending check, interaction equations of Appendix H1 are evaluated
ignoring the axial force term. The expressions are computed using the maximum actions
in the members. If this check fails, the user
For the combined action check for flexure and compression, the member is checked in
accordance with clause H1.1 using the design moments about the major and minor axes.
A more refined
LRFD SAM Clauses Checked
"Load and Resistance Factor Design Specification for Single Angle Members”,
American Institute of Steel Construction, November 10, 2000.
The design checking procedure is the same as described above for LRFD except that:
The section is classified using the limits set out in clause 4 of LRFD SAM. The same
clause is used to compute the slenderness reduction factors and effective area of the
section.
Clause 2 of LRFD SAM is used to determine the tensile capacity of the member.
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