Evaluation of Building Code Formulas for Earthquake Forces

Formulas for base shear, height‐wise distribution of lateral forces, and computation of overturning moment specified in three design documents—Uniform Building Code, Mexico's Federal District Building Code, and ATC‐3 design provisions—are evaluated in light of the results of dynamic analysis of buildings. It is demonstrated that these formulas do not properly recognize the effects of important building parameters, which control the significance of higher mode contributions in the building response. An improved procedure, which recognizes the influence of these parameters, to compute the earthquake forces for the initial, preliminary design of buildings will be presented in a companion paper.