N.Y.C. Admin. Code § 27-577: § 27-577 Shrinkage.

The design of reinforced concrete components shall provide for the forces and/or movements resulting from shrinkage of the concrete in the amount of 0.0002 times the length between contraction joints for standard weight concrete, and 0.0003 times the length between contraction joints for lightweight concrete. The design of arches and similar structures shall provide for effects of shrinkage, plus rib-shortening, plus plastic flow.