4
Findings and Recommendations

Despite large and recurring losses from extreme wind events, no coordinated national program has been established for wind-hazard reduction. For many years, a small community of engineers and scientist has been conducting research into the nature of wind-structure interactions with the goal of improving the performance of structures most commonly damaged by extreme winds. The primary objective of this research is reducing, in an economically acceptable manner, the loss of life and property damage in future windstorms. Results of this research have led to improvements in building coded and standards, but they been applied unevenly in areas of high risk.

When the government formulates and implements a national wind-hazard reduction program, an LSWTF could be used to increase our knowledge and understanding of how residential and other low-rise structures behave in extreme winds. An LSWTF could create loadings for representative storm conditions and enable researchers to study their effects on building and other structures in a controllable, programmable, and repeatable environment. However, despite some favorable attributes, an LSWTF would also have technical limitations and economic drawbacks. Findings and recommendations of the committee are summarized below.

Findings

Finding 1. Wind-structure interactions should be investigated at as close to full-scale as possible.

Although much valuable information can be developed from wind-tunnel tests of small-scale models, computational simulations, and other techniques, the complex interactions that occur within a total structural assembly subjected to extreme winds can only be determined by large-scale or full-scale experiments. In addition, data from large-scale experiments play an important role in validating numerical models and enhancing their credibility.

Finding 2. A variety of methods are available to investigate wind-structure interactions, and each method has both positive and negative aspects.

No single research or experimental method offers a means of reducing losses associated with extreme winds. Ultimately, losses will be significantly reduced only if existing buildings and other structures are remediated and changes are made in the design, construction, inspection, and maintenance of new structures. The committee believes that this can only be accomplished



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4 Findings and Recommendations Despite large and recurring losses from extreme wind events, no coordinated national program has been established for wind-hazard reduction. For many years, a small community of engineers and scientist has been conducting research into the nature of wind-structure interactions with the goal of improving the performance of structures most commonly damaged by extreme winds. The primary objective of this research is reducing, in an economically acceptable manner, the loss of life and property damage in future windstorms. Results of this research have led to improvements in building coded and standards, but they been applied unevenly in areas of high risk. When the government formulates and implements a national wind-hazard reduction program, an LSWTF could be used to increase our knowledge and understanding of how residential and other low-rise structures behave in extreme winds. An LSWTF could create loadings for representative storm conditions and enable researchers to study their effects on building and other structures in a controllable, programmable, and repeatable environment. However, despite some favorable attributes, an LSWTF would also have technical limitations and economic drawbacks. Findings and recommendations of the committee are summarized below. Findings Finding 1. Wind-structure interactions should be investigated at as close to full-scale as possible. Although much valuable information can be developed from wind-tunnel tests of small-scale models, computational simulations, and other techniques, the complex interactions that occur within a total structural assembly subjected to extreme winds can only be determined by large-scale or full-scale experiments. In addition, data from large-scale experiments play an important role in validating numerical models and enhancing their credibility. Finding 2. A variety of methods are available to investigate wind-structure interactions, and each method has both positive and negative aspects. No single research or experimental method offers a means of reducing losses associated with extreme winds. Ultimately, losses will be significantly reduced only if existing buildings and other structures are remediated and changes are made in the design, construction, inspection, and maintenance of new structures. The committee believes that this can only be accomplished

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through a coordinated program of research, education, and technology transfer that integrates available and new knowledge from engineering and the physical and social sciences. Finding 3. An LSWTF has the potential to perform experiments under controlled and repeatable conditions—an option not readily available in experiments with natural wind. In addition, an LSWTF has the potential, as a demonstration medium, for increasing public awareness of building performance in high winds. Repeatable experiments at large-scale in a controlled environment cannot be performed in natural winds. This characteristic sets an LSWTF apart from other experimental method and is the reason the committee believes there may ultimately be a place for an LSWTF in a comprehensive national program for wind-hazard reduction. The ability to demonstrate building performance, including failure, might be useful to focus public interest on the need for mitigation. Finding 4. Alternatives to an LSWTF are available that could potentially provide much of the same data. A variety of tools for research on wind-resistant structures are available, including analysis, numerical computation, wind-tunnel testing of small-scale models, wind-tunnel testing of large-scale of full-scale components, full-scale testing in the natural environment, and large-scale or full-scale testing of components and structures under forces generated by actuators simulating wind action. Finding 5. An LSWTF should only be built if it is part of a national wind-hazard reduction program. It should not precede the program or be considered a substitute for it. Although an LSWTF could play a role in expanding knowledge, improving current practices, and providing demonstrations, experiments conducted at an LSWTF would be only one component of a national wind-hazard reduction program. In that context, it is clearly important to ensure that the costs of building, operating, and maintaining an LSWTF do not preclude the development and application of other more or equally effective facilities, tools, and techniques. Finding 6. An LSWTF is an extremely costly method of producing data that will address only a small fraction of the issues in wind-hazard reduction. The development of an LSWTF should not proceed until such time as the acquisition and operating costs of the facility represent a small fraction of the funds expended on wind-hazard reduction. Alternative methods already exist or can be developed that will provide much more cost-effective solutions for obtaining data and providing demonstrations. In addition, a facility would uniquely address only a small fraction of the pertinent issues in, and impediments to, wind-hazard reduction.

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Finding 7. Construction of an LSWTF is premature. Before an LSWTF could be properly designed and operated, advances would have to be made in understanding the characteristics of extreme winds. In addition, the barriers to the deployment of new technologies and practices for wind-hazard reduction cannot be overcome by engineering research alone. In the absence of a national wind-hazard reduction program, the results produced at an LSWTF are likely to be slow to find their way into practice. Finding 8. Despite recurring and escalating losses from extreme winds, no coordinated national program for wind-hazard reduction currently exists. A number of government agencies have wind-related mitigation and research programs including: FEMA, NOAA, NIST, the National Science Foundation, and DOE. Recently, the subcommittee on Natural Disaster Reduction of the National Science and Technology Council has been actively engaged in developing a national natural disaster reduction plan. However, there is still a lack of leadership, focus, and coordination of wind-hazard mitigation activities across all agencies, and funding for research and development specifically targeting wind-hazard reduction issues is insufficient. Recommendations Recommendation 1. The U.S. Department of Energy should not proceed with a large-scale wind test facility. Recommendation 2. The federal government should coordinate existing federal activities and develop, in conjunction with state and local governments, private industry, the research community, and other interested stakeholder groups, a national wind-hazard reduction program. Congress should consider designating sufficient funds to establish and support a national program of this nature.