Aerodynamic Model Tests of Tall Buildings

Abstract

The theory of the dynamic‐balance wind‐tunnel test is reviewed to identify sources of error that arise when the mode shapes of a structure are nonideal. A systematic process of applying corrections is developed, which results in two adjustment factors—one applicable to displacements and accelerations, and a second applicable to equivalent static loads. The factors are separated into unknown random effects arising from the external wind load distribution and a deterministic effect arising from the structure's mode shape and mass distribution. A simplified assumption on the former is made to evaluate the sensitivity of the correction factors to mode shape and external distribution and to compare them with previous results in the literature. Certain of those results are seen to be misleading in implying that torsional loads should be reduced by a significant, but inappropriate, factor. A simple means of distributing static‐equivalent loads over the height of the structure, while accounting for resonant and background response contributions, is also given.