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 EQUATIONS:
P/Pu + CmxMx/(1 - P/Pex)Mmx + CmyMy/(1 - P/Pey)Mmy
< /= 1.0
(107a)
P/Pp + Mx/1.18Mpx + My/1.18Mpy < /= 1.0 for P/Pp >/= 0.15
(107b)
or:
Mx/Mpx + My/Mpy <_ 1.0 for P/Pp < 0.15
(107c)
where,
Mx, My
=
maximum applied moments about the x- and y-axes
P
=
applied axial load
Pex
=
23/12AF'ex
Pey
=
23/12AF'ey
F'ex
=
122E/[23(K*lb/rx)2]
F'ey
=
122E/[23(K*lb/ry)2]
*lb
=
actual unbraced length in the plane of bending
rx, ry
=
corresponding radii of gyration
Pp
=
AFdy
Cmx, Cmy = coefficients applied to bending term in
interaction formula and dependent upon column
curvature caused by applied moments (AISC
Specification, Section 1.6.1)
Mpx, Mpy = plastic bending capacities about x and y axes
(Mpx = ZxFdy, Mpy = ZyFdy)
Mmx, Mmy = moments that can be resisted by the member in the
absence of axial load.
(a) For columns braced in the weak direction:
EQUATIONS:
Mmx = Mpx
(108a)
Mmy = Mpy
(108b)
(b) For columns unbraced in the weak direction:
EQUATIONS:
Mmx = [1.07 - (*l/ry)(Fdy)1/2/3160]Mpx < /= Mpx(109a)
Mmy = [1.07 - (*l/rx)(Fdy)1/2/3160]Mpy < /= Mpy(109b)
Subscripts x and y indicate the axis of bending about which a particular
design property applies.
2.08-152
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