St. Louis tent collapse raises safety questions – Operational Safety
St. Louis tent collapse raises safety questions
Operational Safety
SUMMARY: St. Louis officials are expected to more closely scrutinize large tents commonly set up near downtown stadiums following a temporary structure collapsing in high winds Saturday. One death of an Illinois man and dozens of injuries after a baseball game occurred.
CBS Report
By Kenneth O’Dell, S.E. M.ASCE, Principal, Firestorm MHP
The forensics associated with this disaster underscores each individual’s personal responsibility for their preparedness and well being during a disaster.
This responsibility includes maintaining an awareness of hazardous weather warnings and Emergency Alert System notifications; as well as, evacuation safe areas/areas of refuge in the immediate locale. The ultimate accountability for personal safety rests with the individual.
How many times have we sat in an unfamiliar movie theater, auditorium, sports arena, or church, without identifying the closest emergency exit and the area of refuge (i.e. restrooms, internal stairwells, etc.)?
Although it appears the tent was properly permitted, installed and inspected, the cautionary statements from City of St. Louis, Building Commissioner Frank Oswald, are noteworthy, “a tent is not a safe place to be in bad weather… tents are temporary structures,” Oswald said. “They are certainly not designed in any stretch of the imagination to handle weather like this.”
From a structural engineering perspective, the typical wind gust used for the design of buildings varies regionally; however, most buildings are designed for constant pressures in the range of 70mph with gusts up to 90 mph for critical zones…hurricane zones are designed for sustained winds in the 90 mph range with 3-second gusts up to 130mph.
Buildings are designed with safety factors in the range of 2-4 for different types of materials and durations of load. Temporary structures such as tents are designed for high loads but are often allowed to have lower safety factors to address the probability of occurrence for an event.
That is to say it is unreasonable to expect a tent which is likely in-place for less than a week to be designed to the same level as a building that will be in place for over 50 years…the allowance is in the safety factors…this means the margin of error is accommodated in the “likelihood” of the windstorm actually happening.
The short-term engineering performance expectations and safety standards related to installing tentage do not provide any degree of comfort for the families that lost loved-ones in this disaster, or for those who were injured; however, all of us should be aware of the limitations of the built environment, whether temporary or permanent. As the Japanese Tsunami shows us…even the best prepared can be dealt a devastating blow.
“What should we do now?” “What should we say?”