The prediction of overall structural wind loads on tall buildings: An assessment of the current state-of-the-art

A number of techniques have been developed by the wind engineering community to determine the overall structural wind loads acting on tall buildings. These include aeroelastic modeling (including full aeroelastic and "stick"-type aeroelastic models), the high frequency force balance (HFFB) method, and the simultaneous pressure integration method. The HFFB method is the most common method of predicting the wind loads acting on wind-sensitive structures due to the relative ease of modeling, testing, and the flexibility in subsequent analyses and predictions. Inherent assumptions of the HFFB method include sway mode shapes that vary linearly with height and uniform torsional mode shape [1]. However, most tall buildings have mode shapes that deviate from these assumptions. A number of authors have proposed methods to correct for the limitations of these assumptions [2,3,4,5,6,7]. A review of the development of the HFFB technique and a discussion of the various methods proposed for correcting for non-linear mode shape is presented in this paper. A comparison of the wind tunnel predictions of the overall response of two tall buildings in Chicago using the HFFB method and two of the proposed mode shape correction methods are also presented. The wind tunnel predictions of the response of the buildings are compared with selected fullscale data recorded as part of a multi-disciplinary research study sponsored by the National Science Foundation (NSF). The authors verify the current state-of-the-art of the HFFB method is effective for prediction of response and structural design of tall buildings.