Joplin, Missouri, Tornado of May 22, 2011

Transcription

1 Joplin, Missouri, Tornado of May 22, 2011 Structural Damage Survey and Case for Tornado-Resilient Building Codes David O. Prevatt, Ph.D., P.E. William Coulbourne, P.E. Andrew J. Graettinger, Ph.D. Shiling Pei, Ph.D., P.E. Rakesh Gupta, Ph.D. David Grau, Ph.D. Published by the American Society of Civil Engineers

2 Cataloging-in-Publication Data on file with the Library of Congress. Published by American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia Any statements expressed in these materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty thereof by ASCE. The materials are for general information only and do not represent a standard of ASCE, nor are they intended as a reference in purchase specifications, contracts, regulations, statutes, or any other legal document. ASCE makes no representation or warranty of any kind, whether express or implied, concerning the accuracy, completeness, suitability, or utility of any information, apparatus, product, or process discussed in this publication, and assumes no liability therefor. This information should not be used without first securing competent advice with respect to its suitability for any general or specific application. Anyone utilizing this information assumes all liability arising from such use, including but not limited to infringement of any patent or patents. ASCE and American Society of Civil Engineers Registered in U.S. Patent and Trademark Office. Photocopies and permissions. Permission to photocopy or reproduce material from ASCE publications can be obtained by sending an to permissions@asce.org or by locating a title in ASCE s online database ( and using the Permission to Reuse link. The front cover photograph is courtesy of the authors; the back cover photograph of downtown Joplin, Missouri, is courtesy of Abe Ezekowitz/Wikimedia Commons. Copyright 2013 by the American Society of Civil Engineers. All Rights Reserved. ISBN (paper) ISBN (PDF) ISBN (EPUB) Manufactured in the United States of America

3 Contents Preface... v Acknowledgments... vii Chapter 1 Joplin Tornado Overview... 1 Chapter 2 Inspection Methodology... 5 Chapter 3 Residential Building Performance Chapter 4 Performance of Commercial Buildings and Critical Facilities Chapter 5 Joplin and a New Tornado Design Philosophy Chapter 6 Proposed Tornado Load Commentary for ASCE Chapter 7 Conclusions and Recommendations References Index... 53

4 Preface This report presents observations, findings, and recommendations from an engineering reconnaissance trip following the May 22, 2011, tornado in Joplin, Missouri. A team of building and construction professionals experienced at high-wind damage investigation was tasked with investigating and documenting the performance of residences and critical buildings [International Building Code (IBC) Occupancy Category II, III, and IV] in Joplin. The Enhanced Fujita (EF) Scale 5 tornado created a 7-mile-long damage swath, destroying over 5,000 buildings in the process and killing over 150 people. The total economic loss from this single event was nearly 25% of the total loss caused by the 1,400 tornadoes that were reported during Spring The Joplin tornado occurred just one month after another tornado devastated Tuscaloosa, Alabama, and together these events caused over $13 billion in economic losses, or approximately 3% of the combined annual Gross Domestic Product (GDP) of the two states. The primary objective of this data collection exercise was to gather information to enable better understanding of predominant structural failure mechanisms associated with tornadic wind loads. The data and recommendations are presented so that they will be used to support future development and/or modification of building design guidelines and standards. While mortality rates in tornado events have been relatively stable, building damage and overall economic losses continue to grow, perhaps due to greater populations living in tornado-prone regions. Tornado damage is particularly extensive when tornadoes impact medium- to large-sized cities with dense concentrations of buildings. There are building design guides in use today by the engineering profession that may mitigate damaging effects from more moderate (EF0 to EF2) tornadic winds. New ways are needed to improve the general level of engineering and construction for residential structures. In addition, revision of structural retrofit practices should be considered for mitigating future losses from tornadoes. The findings from the field study are instrumental in validating recent results on tornado loads from laboratory experiments and numerical analyses. On May 29, 2011, the reconnaissance team arrived in Joplin and was briefed by Federal Emergency Management Agency (FEMA) personnel, city officials, and local structural engineers. In a series of transects perpendicular to the tornado s path, the team observed a gradual reduction in severity of damage from the center of the path towards the edges. Case studies are presented to illustrate common damage patterns and this reduction in damage severity. Many failures were attributed to the lack of continuous vertical and/or lateral load paths, not just to wind speeds that exceeded building code levels. The study team found numerous examples of loadpath failures where detailing in compliance with current building codes for hurricane-prone regions would have reduced the damage and potentially reduced injuries. The findings of the damage assessment team are based on their five days surveying damaged homes, critical facilities, and schools in Joplin. The team used a data collection methodology that documented damage and assigned failure mechanisms to over 150 buildings. The data was collated every day and logged in electronic and hardcopy forms. The team received partial travel support from the American Society of Civil Engineers/Structural Engineering Institute, and it was composed of structural engineers (consultants and academics), wood scientists, and civil engineering students. A blog site was created ( and used to disseminate the team s preliminary findings at the end of each day s investigation.

5 This report is divided into six chapters. Chapter 1 presents an overview of the tornado and its formation and passage across the City of Joplin, as well as summary details of the demographics of the building stock. A description of the data collection methodology used is presented in Chapter 2. Chapter 3 presents detailed findings and descriptions of the damage observed in residential construction, and Chapter 4 presents observed damage in the commercial (engineered) structures and critical facilities. Chapter 5 presents a discussion of the damage in relation to the Enhanced Fujita Scale. Finally, in Chapter 6, summary conclusions and recommendations for the direction of further studies to develop guidelines for tornado-resilient construction are provided. Disclaimer The opinions and views expressed by the authors in this report are theirs alone and do not represent the views of any funding agencies. All information in this report is believed by the authors to be factually correct, but readers should use any information contained herein at their own risk. David O. Prevatt, Ph.D., P.E., University of Florida, Gainesville, FL William Coulbourne, P.E., Applied Technology Council, Washington D.C. Andrew J. Graettinger, Ph.D., University of Alabama, Tuscaloosa, AL Shiling Pei, Ph.D., P.E., South Dakota State University, Brookings, SD Rakesh Gupta, Ph.D., Oregon State University, Corvallis, OR David Grau, Ph.D., University of Alabama, Tuscaloosa, AL

6 Acknowledgments The authors would like to acknowledge the American Society of Civil Engineers/Structural Engineering Institute for their support of this project. The participation of Drs. John van de Lindt and Jim Richardson of the University of Alabama, Mr. Bryan Wert and Mr. Sam Hensen of Simpson Strong Tie, and Dr. Arijit Sinha of Oregon State University is acknowledged. The support of the University of Florida Engineering School for Sustainable Infrastructure and the Environment and the Applied Technology Council is also acknowledged. In addition, we are very appreciative of the efforts provided by two local structural engineers, Mr. John Miller and Mr. Ben Jennings of J&M Engineering, Springfield, Missouri, who assisted with the data collection exercise and by providing valuable local insight on past and present construction practices in Joplin. In addition, Mr. Miller along with Mr. Bob Paullus of Paullus Structural Consultants of Olive Branch, Mississippi, provided insightful comments in their reviews of the final manuscript. The content of this report solely reflects the views of the authors and not the American Society of Civil Engineers. The damage assessment team would like to acknowledge the logistical support provided by Ms. Wesley Parker, FEMA s Mitigation Branch Chief of the Joint Field Office; Mr. Scott Cope, City of Joplin Building Code and Enforcement Supervisor; and support of the FEMA Headquarters Office staff that coordinated daily briefings and provided other valuable information. The following students from the participating universities are also acknowledged for their valuable contributions to this work: University of Florida: Mr. David B. Roueche The University of Alabama: Mr. William (Blake) Doherty Mr. Lane Morrison, Mr. Alireza Geranmayeh South Dakota State University: Mr. Jordan Paul Oregon State University: Ms. Kathryn Pfretzschner