Reqirements for foundations of earthquake-resistant structures are applied automatically according to ACI 18.13
Notation
Ag = gross area of concrete section, in2
As = area of nonprestressed longitudinal tension reinforcement, in2
Ec = modulus of elasticity of concrete, psi
Es = modulus of elasticity of reinforcement, psi
fc' = specified compressive strength of concrete, psi
fy = specified yield strength for nonprestressed reinforcement, psi
Mu = factored moment at section, in.-lb
β = ratio of long to short dimentions; clear spans for two-way slabs, sides of column, concentrated load or reaction area; or sides of a footing
γs = factor used to determine the portion of reinforcement located in center band of footing
According to ACI 18.13.2.1, the provisions of ACI 18.13 should apply to structures assigned to Seismic Design Category D,E or F.
According to ACI 18.13.2.2, Longitudinal reinforcement of columns and structural walls resisting earthquake effects should extend into the footing, mat or pile cap, and should be fully developed for tension at the interface.
According to ACI 18.13.2.3, if the column is designed assuming a fixed-end, it should satisfy ACI 18.13.2.2 requirements. Also, if hooks are required, longitudinal reinforcement resisting flexure should have 90-degree hooks near the bottom of the foundation with the free end of the bars oriented toward the center of the column.
According to ACI 18.13.2.4, transverse reinforcement of columns or boundary elements of special structural walls that have an edge within one-half the footing depth from an edge of the footing should be in accordance with ACI 18.7.5.2 , ACI 18.7.5.3 and ACI 18.7.5.4 (These 3 titles are explained in Transverse Reinforcement (CRD)). This transverse reinforcement should extend into the footing, mat or pile cap a length equal to development length, calculated for fy in tension, of the column or boundary elemant longitudinal reinforcement.
According to ACI 18.13.2.5, where uplift force occurs due to earthquake effects in boundary elemants of special structural walls or columns, flexural reinforcement should be provided in the top of the footing, mat, or pile cap to resist actions resulting from the factored load combinations, and should. Minimum area of flexural reinforcement, As,min should be 0.0018Ag.