Front matter for State of the Art and Research Needs in Design for Tornadoes to Improve Community Resilience

Minimum Design Loads and Associated Criteria for Buildings and Other Structures, ASCE/SEI 7-22, prepared by the Minimum Loads and Associated Criteria for Buildings and Other Structures Standards Committee (ASCE/SEI 2022). This standard provides the most up-to-date and coordinated loading provisions for general structural design. (ISBN 978-0-7844-1578-8)

ASCE/SEI Prestandard for Performance-Based Wind Design V1.1, prepared by the Structural Engineering Institute (ASCE/SEI 2023). This prestandard presents recommended alternatives to the prescriptive procedures for wind design of buildings contained in the nationally adopted ASCE 7 and the International Building Code. (ISBN 978-0-7844-8473-9)

Design and Performance of Tall Buildings for Wind, edited by Preetam Biswas and John Peronto (ASCE/SEI 2020). MOP 143 provides a framework for the design of tall buildings for wind, based on the current state-of-practice in tall building structural design and wind tunnel testing. (ISBN 978-0-7844-1565-8)

Wind Issues in the Design of Buildings, edited by Leighton Cochran (ASCE/SEI 2012). This book explains the ways that structural designers accommodate the impact of extreme wind events on the built environment. (ISBN 978-0-7844-1225-1)

Joplin, Missouri, Tornado of May 22, 2011: Structural Damage Survey and Case for Tornado-Resilient Building Codes, by David O. Prevatt, William Coulbourne, Andrew J. Graettinger, Shiling Pei, Rakesh Gupta, and David Grau (ASCE/SEI 2012). This report presents the observations, findings, and recommendations of an engineering reconnaissance team that surveyed structural damage to residential buildings and schools in Joplin, Missouri, caused by an EF 5 tornado event. (ISBN 978-0-7844-1250-3)

Moore, Oklahoma, Tornado of 2013: Performance of Schools and Critical Facilities, by William L. Coulbourne, David O. Prevatt, T. Eric Stafford, Christopher C. Ramseyer, and John M. Joyce (ASCE/SEI 2015). This report presents the observations and recommendations of a team of structural engineers and construction specialists who assessed the structural damage to critical facilities following the 2013 Moore, Oklahoma, tornado. (ISBN 978-0-7844-1409-5)

Urban Aerodynamics: Wind Engineering for Urban Planners and Designers, by the Task Committee on Urban Aerodynamics (ASCE/Technical Council on Wind Engineering 2011). This report introduces the basic tools and technology used by engineers to determine the effects of wind on city streets and structures. (ISBN 978-0-7844-1179-7)

This report summarizes an important collective effort by the current world-leading experts in wind engineering and tornado resilience to develop a road map for improvements in the understanding and characterization of tornado hazards for building design. This effort is timely considering the increasing trend of fatalities and staggering economic losses that continued to be induced by severe weather events in the United States in the last several decades. In 2023 alone, severe convective storms caused a record-setting $21 billion insured loss events and a total of $73 billion in economic loss, an amount that represents nearly 65% of the total economic losses caused by all other natural hazards for that year.

Thanks to the efforts of Don Scott, P.E., S.E., F.SEI, F.ASCE, a preeminent practitioner in wind and structural engineering, and Jennifer Goupil, P.E., F.SEI, F.ASCE, SEI Managing Director and ASCE Chief Resilience Officer, alongside a broad spectrum of recognized leaders in the tornado resilience field, through a Measurement Science and Engineering grant from the National Institute of Standards and Technology (NIST) in 2023, we now have a more detailed understanding of the current state of the art and associated challenges in tornado-resilient design and the prioritized research needs in several specific areas for further improvement in understanding of tornado hazards and how they affect the built environment. It is strongly believed that a more accurate characterization of tornado hazards in building codes and standards will ultimately lead to safer and more economical tornado-resistant design and improved tornado resilience for US communities.

It is also believed that the detailed research needs identified in this report will be a valuable resource for developing new teaching materials and educational curriculums at academic institutions in the United States.

Finally, the primary mission of the NIST's National Windstorm Impact Reduction Program is to achieve major, measurable reductions in losses of life and property from windstorms through a coordinated federal effort, in cooperation with other levels of government, academia, and the private sector. It is with sincere gratitude and great satisfaction that I acknowledge this collective effort from the broad wind engineering community, as it represents the firm commitment toward achieving this important mission.

In September 2023, the Structural Engineering Institute (SEI) of American Society of Civil Engineers (ASCE) commenced a project under Grant number 60NANB23D268 from the National Institute of Standards and Technology (NIST) to plan and execute a workshop to develop a research road map on tornado hazard research and advancement to improve community resilience. This report documents the results of this workshop. The workshop and subsequent research road map for the standardization and application of tornado design has been developed by wind engineering practitioners, building design professionals, product developers, federal agency partners, not-for-profit organizations, academics, and researchers for buildings and other structures.

The impetus for the project stems from the extensive casualties and property losses that have occurred over the last few decades because of damaging tornadoes in the United States. SEI and NIST have continued to provide leadership in the development of design standards, including tornadic events, which will lead to more resilient communities across the nation.

The workshop process included a review of the literature, which identified the issues and research needs in the areas of tornado climatology and near-surface wind characteristics, tornado–structure interaction, design of residential structures, and current building design using the provisions of ASCE 7, Design of Tornado Shelters and Safe Rooms, and Tornado Effects on Nonbuilding Structures and Beyond ASCE/SEI 7. This review was followed by an extensive workshop preparation process, a two-day workshop to obtain input from experts in these areas, report preparation, report review by a peer-review panel, and publication of this report.

This work was performed under the following financial assistance award 60NANB23D268 from U.S. Department of Commerce, National Institute of Standards and Technology. SEI is indebted to the leadership of Donald Scott, P.E., S.E., F.SEI, F.ASCE, who served as the Workshop Director; the SEI Staff – especially Bianca Augustin and Katie Stueckle – who served as the Workshop Coordinators, the Workshop Steering Committee members Alex Griffin, P.E., S.E, M.ASCE; Cherylyn Henry, P.E., F.SEI, F.ASCE; Marc Levitan, Ph.D., F.SEI, M.ASCE; Frank Lombardo, Ph.D., EIT, A.M.ASCE; John van de Lindt, Ph.D., F.SEI, F.ASCE; and Peter Vickery, Ph.D., P.E., F.SEI, F.ASCE, NAE for their contributions in development of the workshop and this report. In addition, SEI wishes to acknowledge the contributions of the Workshop Steering Committee scribes: Shane Crawford, Ph.D., A.M.ASCE; John Haney, A.M.ASCE; Blythe Johnston, S.M.ASCE; Lauren Mudd, Ph.D. P.E., M.ASCE; Korah Parackal, Ph.D., CPEng, A.M.ASCE; and Zach Wienhoff for helping to document the discussions and prepare the final report. Special recognition is given to Shane Crawford for leading the in-person workshop breakout session and initial report writing due to unforeseen circumstances and the temporary absence of Marc Levitan. The assistance of Scott Tezak with the storm shelter breakout session is also gratefully acknowledged.A special thanks is extended to the Peer Review Team who reviewed and provided comments on this report. The Peer Review Team included Gregory Kopp, Ph.D., P.E., M.ASCE from Western University, Melissa Burton, Ph.D., P.Eng., M.ASCE from Arup, Sudhan Banik, Ph.D., P.E., M.ASCE from Applied Research Associates, Kishor Mehta, Ph.D., P.E., F.SEI from Texas Tech University, and Daniel Rhee, Ph.D. from NIST. Appreciation is also extended to the many individuals who participated in the workshop and gave their time and shared their knowledge. Appendix D lists the names and affiliations of all who contributed to this report.

The Structural Engineering Institute (SEI) has a long history of working with NIST and other federal partners to improve ASCE/SEI 7, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, the national loading standard. Following the Joplin, Missouri, tornado of 2011, NIST investigated the event and published its recommendations in Technical Investigation of the May 22, 2011, Tornado in Joplin, Missouri (NIST 2014) to improve the understanding of the climatology of tornadoes and development of design standards for the tornado hazard. Recommendation No. 5 from this report is as follows:

Recommendation No. 5: NIST recommends that nationally accepted performance-based standards for tornado-resistant design of buildings and infrastructure be developed and adopted in model building codes and local regulations to enhance the resiliency of communities to tornado hazards. The standards should encompass tornado hazard characterization, performance objectives, and evaluation tools. The standards shall require that critical buildings and infrastructure such as hospitals and emergency operations centers be designed to remain operational in the event of a tornado.

This recommendation was assigned to ASCE and SEI. It led to the development of the first set of tornado design provisions in the world in the 2022 edition of ASCE/SEI 7. This workshop identified the next steps in the development of the standard provisions and performance objectives for performance-based design procedures.

The workshop brought together many of the leading experts in tornado climatology, interaction with the built environment, the design of structures for tornadoes, and community resilience to evaluate the current societal needs and to further our understanding of the tornado hazard.

The workshop identified a broad range of research and development activities to advance the standardization of tornado design provisions with the goal of reducing the impacts of these severe tornadic events.

This report includes a discussion of research needs in multiple areas and specific recommendations on the following 10 priority research needs identified by the workshop participants: