Q: Do we need to use cracked section in drift check?
A: ACI 318-14 Section 6.6.3.2 addresses the service load analysis, which would seem to include drift, although it doesn’t say that explicitly. Section 6.6.3.2.2 states that for such analyses it is permitted to use moments of inertia that are 1.4 times those defined in 6.6.3.1, which is the section that requires the use of cracked moments of inertia. The Commentary to Section 6.6.3.2.2 does refer to using this greater value in the investigation of deflections, vibrations, and building periods, so it seems reasonable to also use this greater value when investigating drifts.
