Slender Column Moment Magnifier, Nonsway (ACI 318-19 6.6.4)
The ACI 318-19 6.6.4.5 nonsway P-delta moment magnifier delta_ns = Cm/(1 - Pu/(0.75 Pc)) and the magnified design moment Mc a slender braced reinforced-concrete column picks up. A column just over the slenderness limit gains a 1.3-1.7x amplifier the flexure check never applies; floored at M2,min.
Formula and source
Cm = max(0.6 + 0.4 M1/M2, 0.4); Pc = pi^2 EI / (k lu)^2; delta_ns = max(Cm/(1 - Pu/(0.75 Pc)), 1.0); Mc = max(delta_ns M2, M2,min), M2,min = Pu(0.6 + 0.03 h).
The ACI 318-19 Section 6.6.4.5 nonsway (braced) slender-column moment magnifier, by name.
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