N.Y.C. Admin. Code § 27-578: § 27-578 Distribution of vertical loads.

Distribution of vertical loads to supporting members shall be determined on the basis of a recognized method of elastic analysis or system of coefficients of approximation. Elastic or inelastic displacements of supports shall be considered and, for the distribution of dead loads, the modulus of elasticity of concrete or composition sections shall be reduced to consider plastic flow. Secondary effects, due to warping of the floors shall be considered.