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D1.B.1.1.5 Combined Compression and Bending

Members subjected to both axial compression and bending stresses are proportioned to satisfy AISC formula H1-1 and H1-2 when fa/Fa is greater than 0.15, otherwise formula H1-3 is used. It should be noted that during code checking or member selection, if fa/Fa exceeds unity, the program does not compute the second and third part of the formula H1-1, because this would result in a misleadingly liberal ratio. The value of the coefficient Cm is taken as 0.85 for sidesway and 0.6 - 0.4 (M1/M2), but not less than 0.4 for no sidesway.