Equation F.1-1 – AISC 360-16

This equation calculates the lateral-torsional buckling modification factor for non-uniform moment diagrams.

C_{b} = \frac{12.5 M_{\max}}{2.5 M_{\max} + 3 M_{A} + 4 M_{B} + 3 M_{C}}

C_b	Lateral-torsional buckling modification factor for non-uniform moment diagrams
M_max	Absolute value of the maximum moment in the unbraced segment
M_A	Absolute value of the moment at the quarter point of the unbraced segment
M_B	Absolute value of the moment at the centerline of the unbraced segment
M_C	Absolute value of the moment at the three-quarter point of the unbraced segment

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