About this Research Topic
Global economic losses due to severe weather events have been growing dramatically over the past two decades. A large proportion of these are due to severe wind storms, which can cause destruction over large areas, as in the case of tropical cyclones, or relatively small areas, as in the case of tornadoes.
The primary tool of wind engineering has been the boundary layer wind tunnel. One of the earliest studies in the modern-era of wind engineering was conducted by Jack Cermak and Alan Davenport in the early 1960s for the World Trade Center towers. Since that time, wind design for tall buildings and long bridges has become reasonably standardized, with many boundary layer wind tunnels built around the world to determine wind loads and responses of these types of engineered structures. Such wind tunnels typical use length scales in the range from about 1/200 to 1/500.
Post-event damage surveys and analysis of loss data indicate that much of the damage and losses in wind-related natural disasters is to residential structures, which, in many locations of the world, are not engineered. However, even engineered buildings can sustain considerable damage, although this is typically to building envelope (e.g., cladding systems). Significant failures of structural systems are relatively rare. Non-engineered structures are complex to analyze since they often utilize materials which do not have reliable (i.e., engineered) properties but which can have a significant impact on real-world performance. Such buildings often have structural systems which are ill-defined, such as wood-frame houses in North America, where non-structural materials play a significant roll. Cladding systems on engineered buildings also present challenges, especially multi-layer systems where typical wind tunnel model scales are seldom large enough to resolve important details.
The wind field itself also presents unique challenges, particularly for the smaller, fast moving storms, such as those that occur during thunderstorms. Tornadoes, for example, have complex flow structures that are not at all suited to straight-line wind tunnels since the flow is primarily rotational and may have large vertical components. Even the straight-line flows that occur in downbursts or gust fronts may not be appropriate since such flow fields have sharp spatial and temporal gradients, with different vortical structures in the flow. While design for such types of storms has not generally occurred historically, particularly for non-engineered buildings, rising losses have lead some communities and designers to begin to consider this.
To address the growing losses, many new large-scale and full-scale laboratories have been developed to solve many of the particular issues that could not be solved with traditional boundary layer wind tunnels, testing laboratories or methods of analysis. The purpose of this Research Topic is to discuss in detail some of these issues with a particular emphasis on the large-scale and full-scale laboratory-based approaches being developed to address them.
Keywords: Natural disaster mitigation, wind loads, non-synoptic wind storms, large-scale testing, components & cladding