AISC LRFD 1.pdf

App. H3.] ALTERNATIVE INTERACTION EQUATIONS 113C m = coefficient applied to the bending term in the interaction equation forprismatic members and dependent on column curvature caused byapplied moments, see Section C1.M¢ = 1.2M éë1 -( P / P)ùû£Mpx px u y pxM¢ = 1.2M éë1 -( P / P)ùû£M2py py u y pyæ P öæ P öM¢ çè÷çøè÷øMuunx= Mnx1- 1-fcPn Pexæ P öæP ö= - -uuny¢ Mnyç 1 1fcPçnP÷è÷øè eyø(A-H3-5)(A-H3-6)(A-H3-7)(A-H3-8)(b) For box-section members:zPu/ Py= 1.7 - 1n( P / P )uy(A-H3-9)For PFor Puu/ P £ 40, . a = 0.06, and b = 1.0;y/ P > 40, . a = 0.15, and b = 2.0:yP / P æPöh = 1.7 - - > 1.11n( / )ç ÷øu y ualxPu Py èPyM¢ = 1.2M ëé1 - P / P ûù£Mpx px u y pxM¢ = 1.2M ëé1 - P / P ûù£Mpy py u y pyb(A-H3-10)(A-H3-11a)(A-H3-11b)æ P öæuPu1.25 öMnx¢ = Mnxç1- 1-(A-H3-12)è fcP ÷çnøè Pex( B/ H)1/3 ÷øæ P öæuPu1.25 öM(A-H3-13)ny¢ = Mnyç 1- 1fcP ç -nPeyB H 1/2 ÷è÷øè ( / ) øwhereP n = nominal compressive strength determined in accordance with SectionE2, kips (N)P u = required axial strength, kips (N)P y = compressive yield strength A g F y , kips (N) b = resistance factor for flexure = 0.90 c = resistance factor for compression = 0.852P e = Euler buckling strength A g F y / c , where c is the column slendernessparameter defined by Equation E2-4, kips (N)M u = required flexural strength, kip-in. (N-mm)LRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION