Introduction

In our exploring the new building height (Fig. 1), horizontal loads like the windstorms and earthquakes post more challenges than the vertical loads such as the building and facility weight.

Fig. 1. Historically Tallest Towers (http://www.skyscripter.org/)

As building increases in height, the vertical load increases linearly with the height; while the horizontal loads induce a base bending moment that is proportional to the square of the building height (Fig. 2).

Fig. 2. Increases of Loads and Effects With Building Heights

Generally, there are two major sources of horizontal loads: the earthquakes and the windstorms. In the frequency domain, each of them dominates at different frequency range (Fig. 3). The design of normal low-rise buildings may be controlled by the earthquake actions, while tall buildings and those skyscrapers may be governed by the windstorms.

Fig. 3. Frequency Features of Earthquakes and Windstorms

Windstorms impact the design and performance of tall buildings in the following ways: (1) Pedestrian level wind environment; (2) Design of cladding systems; (3) Survivability; and (4) Serviceability.

In most situations, the information of wind loads and effects on the structures is needed to ensure reliable design and desirable building performance, thus reducing significantly wind-induced damages and losses.

The study of tall building aerodynamics can provide us more accurate understanding of wind loads and effects, as well as tools to mitigate them.

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ã Copyright, NatHaz Modeling Laboratory, University of Notre Dame