B Questionnaire, Respondents, and Synthesis of Responses

Questionnaire

The National Research Council, through the Board on Infrastructure and the Constructed Environment, has been requested by the Department of Energy to assess the need for a wind testing facility capable of subjecting full-scale, non-engineered structures (such as homes and small commercial buildings) to extreme wind conditions. This assessment must be completed by March 1, 1999. In order to assist the panel conducting the assessment, we are soliciting the views of a broad segment of those concerned with the effects of extreme winds on non-engineered structures.

The task of the panel is to:

  • review the need for a large-scale experimental wind engineering facility
  • identify the potential benefits of such a facility
  • assess the priority for large-scale physical testing as a component of a national wind engineering research program

To assist them in addressing their task, the panel requests your input on the following questions:

    1)  

    What is the need for large-scale experimental data in gaining scientific understanding of the effects of extreme wind events on non-engineered structures?

    2)  

    What are the benefits of generating data on extreme wind events in a controlled environment, rather than collecting field data in natural wind or performing post-storm inspections?

    3)  

    What is the value of data produced by large-scale, full-system testing vs. small-scale or component testing?

    4)  

    What is the value of large-scale testing to develop and validate computer simulations, as a vehicle for public education, to validate current building code prescriptive standards, and to aid in the design of credible standardized small-scale or single component tests?



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    B Questionnaire, Respondents, and Synthesis of Responses Questionnaire The National Research Council, through the Board on Infrastructure and the Constructed Environment, has been requested by the Department of Energy to assess the need for a wind testing facility capable of subjecting full-scale, non-engineered structures (such as homes and small commercial buildings) to extreme wind conditions. This assessment must be completed by March 1, 1999. In order to assist the panel conducting the assessment, we are soliciting the views of a broad segment of those concerned with the effects of extreme winds on non-engineered structures. The task of the panel is to: review the need for a large-scale experimental wind engineering facility identify the potential benefits of such a facility assess the priority for large-scale physical testing as a component of a national wind engineering research program To assist them in addressing their task, the panel requests your input on the following questions: 1)   What is the need for large-scale experimental data in gaining scientific understanding of the effects of extreme wind events on non-engineered structures? 2)   What are the benefits of generating data on extreme wind events in a controlled environment, rather than collecting field data in natural wind or performing post-storm inspections? 3)   What is the value of data produced by large-scale, full-system testing vs. small-scale or component testing? 4)   What is the value of large-scale testing to develop and validate computer simulations, as a vehicle for public education, to validate current building code prescriptive standards, and to aid in the design of credible standardized small-scale or single component tests?

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    5)   What would be the cost of generating data in a facility capable of subjecting full-scale, non-engineered structures to extreme winds, relative to the costs of collecting data from full-scale tests in natural wind, small-scale or component testing, or performing post-storm inspections? 6)   Given the relative costs of the various data collection methods and the relative value of the data each produces, which methods represent the most cost-effective ways of improving the scientific understanding of the effects of extreme winds on non-engineered structures? 7)   Which industries would be the most likely to use a facility capable of testing full-scale structures in a controlled environment and to what extent are they likely to use it? Your response to these questions may be as detailed and lengthy as you wish but please try to highlight your critical points. The panel will hold its first meeting in mid-November and it would be most helpful if you could respond by October 30, 1998. Please respond by fax to (202) 334-3370 or by email to mporterf@nas.edu. Name: Title: Organization: Address: Phone: Fax: e.mail:

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    Respondents Vince A. Amatucci Senior Member of Technical Staff Aerosciences and Compressible Fluid Mechanics Department Sandia National Laboratories Albuquerque, New Mexico Maurice Bazin Deputy Director Large Technical Facilities Office National d'Etudes et de Recherches Aerospatiales Paris, France Joseph Golden Senior Meteorologist National Oceanic and Atmospheric Administration Silver Spring, Maryland Michael J. Griffin Technical Manager Associate EQE International St. Louis, Missouri George Housner Carl F. Braun Professor of Engineering, Emeritus California Institute of Technology Pasadena, California Bonnie Johnson Director Aerodynamic Laboratories National Institute for Aviation Research Wichita State University Wichita, Kansas Atul L. Khanduri Senior Engineer Risk Management Solutions, Inc. Menlo Park, California Richard D. Marshall Retired Building and Fire Research Laboratory National Institute of Standards and Technology (NIST) Gaithersburg, Maryland Jorge L. Martinez Director Low Speed Wind Tunnel Texas Engineering Experiment Station Aerospace Engineering Division Texas A&M University College Station, Texas Jim McDonald Department Chair Civil Engineering Texas Tech University Lubbock, Texas Kishor Mehta Director Wind Engineering Research Center Texas Tech University Lubbock, Texas Jim Merva Technical Underwriting Director St. Paul Fire and Marine Insurance Company Saint Paul, Minnesota Eugene E. Niemi, Jr. Professor University of Massachusetts-Lowell Lowell, Massachusetts Mark Perry Lead Projects Engineer Lockheed Martin Low Speed Wind Tunnel Smyrna, Georgia

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    Jon Peterka Vice President Cermak Peterka Petersen, Inc. Wind Engineering Consultants Fort Collins, Colorado Emil Simiu NIST Fellow Building and Fire Research Laboratory National Institute of Standards and Technology Gaithersburg, Maryland Dave Surry Research Director Boundary Layer Wind Tunnel Laboratory University of Western Ontario London, Ontario Canada Terry C. Taylor Principal Consulting Engineer Haag Engineering Houston, Texas Henry Tieleman Professor Emeritus Engineering Science and Mechanics Virginia Polytechnic Institute and State University Blacksburg, Virginia Christian O. Unanwa Assistant Professor South Carolina State University Orangeburg, South Carolina George R. Walker Operations Director-Strategic Development Aon Re Australia Sydney, Australia Pete Zell Ames Research Center National Aeronautics and Space Administration Moffett Field, California Synthesis of Responses Twenty-two people responded to the questionnaires. The respondents, in general, indicated that full-scale or large-scale testing is important and that a large-scale facility could be a useful tool in wind engineering research. There was no agreement among them on whether or not a large-scale facility was necessary to obtain important data or if other testing methods (e.g. full-scale testing in natural wind) could provide the same information. Several of them indicated that interdisciplinary, coordinated research will be necessary to mitigate wind-related losses and that no facility should be established except as part of a well conceived national program. The respondents highlighted many benefits of a facility capable of testing large-scale structures in a simulated extreme wind environment, but they expressed concerns about the capability of such a facility to simulate the characteristics of the natural wind, as well as the potential costs, both startup and maintenance costs, of such a facility. In addition, some respondents noted that there are many large wind tunnels in this country that, with modification, might provide badly needed data and that these options should be fully explored before significant funds are devoted to the construction of a new facility.

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    Below are summaries of the responses to each question. 1) What is the need for large-scale experimental data in gaining scientific understanding of the effects of extreme wind events on non-engineered structures? In general, the respondents indicated that there is a need for large-scale experimental data to help the public understand the relationship between wind speeds and wind damage. The misrepresentation of wind speeds in past extreme wind events may have misled the public about the destructive power of extreme winds. In addition, large-scale data could be useful for calibrating and validating small-scale or component tests. There was no consensus among the respondents as to whether or not a facility for research on the effects of extreme wind conditions on structures is necessary to obtain this data. Some respondents expressed concerns about the ability of such a facility to simulate wind flows and loading from small-scale vortices like tornadoes. Others expressed concerns about cost and the number of users for such a facility. Some equivalent data could be obtained more cheaply by other methods, such as measurements of wind loads, which can be made with existing facilities. However, no existing facility is capable of large-scale destructive testing, and there is a very low probability of destructive force winds hitting an instrumented structure in the field. Some respondents felt that conclusions from an ensemble of full-scale studies were likely to be significantly more valuable than those reached from any individual experiment. They also stressed the importance of coordinated national research programs. 2) What are the benefits of generating data on extreme wind events in a controlled environment, rather than collecting field data in natural wind or performing post-storm inspections? The respondents were in general agreement that a well planned, full-scale facility capable of capturing the characteristics of natural wind has some distinct advantages over collecting field data in natural wind or performing post-storm inspections. The most common benefit highlighted by the respondents was the potential ability for quick results through experimental control. With a full-scale facility, there would be no waiting for the "big one" to hit the instrumented structure. The level of control over wind velocity, temperature, barometric pressure, and other variables would be much greater in a wind simulation facility than in natural wind. Additional advantages include the ease of instrumenting and observing the behavior of the test structure. Another important benefit of a full-scale facility is the capability of repeating test conditions. Many respondents again pointed out that no single data collection method would be adequate, and that an interdisciplinary approach would be necessary. 3) What is the value of data produced by large-scale, full-system testing vs. small-scale or component testing? Although respondents highlighted many benefits of full-scale testing over small-scale or component testing, they also pointed out that tests at all scales have significant and complementary value and should be a part of an integrated national program. Full-scale testing can reveal some of the more subtle aspects of fluid mechanics and eliminate some difficult

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    scaling issues, such as how to scale material properties. In addition, full-scale testing would allow for the determination of correct natural frequencies of structural systems and enable the study of aerodynamic and structural interactions and end or boundary fixity conditions between components that cannot be easily simulated by testing one piece at a time. The proposed facility would enable studies of progressive damage to failure so that the wind speeds associated with the onset of specific damage could be determined. A full-scale testing facility could be good publicity and increase public awareness of the dangers posed by winds, provided the characteristics of extreme winds were adequately simulated and the costs of the facility were not so extreme that it would negatively affect public opinion about artificial destructive testing. 4) What is the value of large-scale testing to develop and validate computer simulations, as a vehicle for public education, to validate current building code prescriptive standards, and to aid in the design of credible standardized small-scale or single component tests? The respondents indicated that it is clearly necessary to validate computer simulations, building codes, and small-scale or component tests. If a large-scale facility could properly model the natural wind, it might contribute to these validations. The question raised by many respondents, however, is whether or not there are more cost-effective ways to validate methods. It was suggested, for example, that computer simulations can be validated by field measurements and that code verification can be done with laboratory experiments. The use of a large-scale facility as a vehicle for public education was also a point of debate among the respondents. While many believed that it would be educational and useful for people to see video footage of structures being blown apart in a facility, others argued that footage from actual events, during or after storms, sends a much stronger message than "fake" destruction. Others indicated that they felt there were equally effective and less expensive ways to educate the public. 5) What would be the cost of generating data in a facility capable of subjecting full-scale, non-engineered structures to extreme winds, relative to the costs of collecting data from full-scale tests in natural wind, small-scale or component testing, or performing post-storm inspections? In general, the respondents seemed to be in agreement that a large-scale facility would be extremely expensive to build and operate. Many agreed that many other projects could be funded for the price of constructing a facility of this type. However, as one respondent pointed out, the costs of rebuilding non-engineered structures after a storm are also very large, and these costs should be considered when budgeting for wind engineering research. Even though the facility would be expensive, getting some data, especially failure data, through other means (e.g. full-scale testing to destruction in natural wind) would be virtually impossible. Paying large sums of money for unique, high-quality data may be appropriate and necessary for effectively mitigating wind-hazards. Several respondents pointed out that scaling is difficult in small-scale (especially destructive) testing, but that small-scale and component tests have been beneficial in the past and would continue to be so. Large-scale, full-system testing may have advantages over component testing because the aerodynamic interactions between various components could be studied. One

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    respondent pointed out the advantages of full-scale testing over post-storm inspections, which may not yield accurate data because they are subjective and because recording devices capable of accurately depicting structure-level wind conditions throughout the storm are not readily available. Given this current lack of ground-level wind data during extreme wind events, it might be premature to construct a simulation facility, especially given the fact that other methods (e.g. full-scale field and component testing) have been beneficial in the past. 6) Given the relative costs of the various data collection methods and the relative value of the data each produces, which methods represent the most cost-effective ways of improving the scientific understanding of the effects of extreme winds on non-engineered structures? There was a wide range of opinions about which method of testing is most cost-effective. Several respondents indicated that they felt that a full-scale test facility would be the most cost-effective data collection method, while others argued that the enormous start-up and maintenance costs of such a facility would put it out of reach of anyone except the government. Some pointed out that post-storm surveys are a relatively inexpensive way of collecting data about existing structures and should be continued. During severe storms, many structures are exposed to winds of similar magnitude simultaneously, and good comparisons can be made of different construction techniques. Other respondents indicated that small-scale tests have been valuable in the past and can continue to contribute to the knowledge base. Well planned small-scale testing with a few carefully executed full-scale or large-scale studies could greatly improve our understanding of wind effects on structures. They also pointed out that a number of facilities in the United States (e.g. wind tunnels at NASA Ames Research Center) might be adaptable for large-scale testing on wind effects on structures. 7) Which industries would be the most likely to use a facility capable of testing full-scale structures in a controlled environment and to what extent are they likely to use it? Respondents suggested that the customer base would depend on the flexibility of the facility, the perceived realism of the wind simulation, and the cost per experiment. Serious concerns were raised by some respondents about whether or not anyone, except possibly the government, would have the financial resources to support full-scale or large-scale testing in such a facility. Possible customers that were suggested include: insurance industry government agencies construction industry prefabricated building industry educational institutions building code developers code enforcement authorities risk management companies roofing, component, and cladding companies