D11.A.4.2Bending
Bending capacities are calculated per NZS3404 Section 5. The allowable bending moment of members is determined as the lesser of nominal section capacity and nominal member capacity (ref. Cl.5.1).
D11.A.4.2.1Bending Section Strength
The nominal section moment capacity, ϕMs , is calculated about both principal x and y axes and is the capacity to resist cross-section yielding or local buckling and is expressed as the product of the yield stress of the material and the effective section modulus (ref. Cl.5.2.1). The effective section modulus is a function of section type (i.e., compact, non-compact, or slender) and minimum plate yield stress fy. The nominal member capacity depends on overall flexural-torsional buckling of the member (ref.Cl.5.3).
D11.A.4.2.2Bending Member Strength
For sections where the web and flange yield stresses (fy,web and fy.flange respectively) are different, the lower of the two yield stresses is applied to both the web and flange to determine the slenderness of these elements.
For sections where the web and flange yield stresses (fy,web and fy.flange respectively) are different, the lower of the two yield stresses is applied to both the web and flange to determine the slenderness of these elements. Member moment capacity, φMb , is calculated about the principal x axis only (ref. Cl.5.6). Critical flange effective cross-section restraints and corresponding design segment and sub-segments are used as the basis for calculating capacities.
The
ALM design parameter is used to specify
αm
(refer cl. 5.6.1.1).
The
SKR,
SKT,
SKL,
UNT,
UNB, and
PBRACE design parameters are also used for bending
checks.