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On the afternoon of May 2, 2009, during a severe thunderstorm, the Dallas Cowboys indoor practice facility collapsed, injuring 12 people, one seriously. In response to this building collapse, NIST deployed a reconnaissance team that arrived at the collapse site on May 12, 2009. The reconnaissance team: (1) surveyed and documented the collapsed structure, (2) surveyed other wind damage in the area surrounding the site, and (3) collected relevant data and information on the structure from the Dallas Cowboys organization and the City of Irving, Texas. Based upon the initial field reconnaissance, NIST determined that sufficient information was available to conduct a study of the collapse.
The objectives of the NIST study were to (1) determine why and how the Dallas Cowboys practice facility collapsed and (2) identify areas for improvement to current building codes, standards, and practices for this type of structure.
Based on data acquired during a reconnaissance of the collapsed facility, NIST developed a two-dimensional computer model of a typical structural frame and then analyzed that frame to study its performance under various wind conditions. NIST worked with the National Oceanic and Atmospheric Administration's (NOAA) National Severe Storms Laboratory to estimate the wind conditions at the time of collapse. The researchers determined that, at the time of collapse, the wind was blowing perpendicular to the long side of the building. Maximum wind speed gusts at the time of collapse were estimated to be in the range of 55 to 65 miles per hour—well below the design wind speed of 90 miles per hour as specified in the national standard for wind loads. NIST and NOAA analyzed the available wind data and concluded that a microburst (a small, intense downdraft which results in a localized area of strong winds) was centered about one mile southwest of the structure at the time of collapse. The wind field in the vicinity of the structure was predominately lateral, as assumed in design.
NIST is working with various public and private groups toward implementing changes to practice, standards, and building codes based on the findings from this study.
The report, "Final Report on the Collapse of the Dallas Cowboys Indoor Practice Facility, May 2, 2009 (NIST IR 7661)," summarizes the study and its findings.
Buckling of the steel frame of the Dallas Cowboys practice facility is seen in the upper left of the photograph (marked by arrow). Photo credit: NIST.