AISC LRFD 1.pdf

Sect. H3.] ALTERNATIVE INTERACTION EQUATIONS 392. Doubly and Singly Symmetric Members in Flexure and CompressionThe interaction of flexure and compression in symmetric shapes shall be limited byEquations H1-1a and H1-1bwhereP u = required compressive strength, kips (N)P n = nominal compressive strength determined in accordance with Section E2,kips (N) = c = resistance factor for compression = 0.85 (see Section E2) b = resistance factor for flexure = 0.90H2. UNSYMMETRIC MEMBERS AND MEMBERS UNDER TORSION ANDCOMBINED TORSION, FLEXURE, SHEAR, AND/OR AXIAL FORCEThe design strength, F n , of the member shall equal or exceed the required strengthexpressed in terms of the normal stress f un or the shear stress f uv , determined by elasticanalysis for the factored loads:(a) For the limit state of yielding under normal stress:f un F n (H2-1) = 0.90F n = F y(b) For the limit state of yielding under shear stress:f uv 0.6F n(H2-2) = 0.90F(c) For the limit state of buckling: n = F yf un or f uv c F n, as applicable(H2-3) c = 0.85FSome constrained local yielding n = Fis permitted cradjacent to areas which remainelastic.Errata9/4/01H3. ALTERNATIVE INTERACTION EQUATIONS FOR MEMBERS UNDERCOMBINED STRESSSee Appendix H3.LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION