Stronger building codes could have saved lives in Joplin tornado, federal report says
11/21/2013 8:16 PM
11/21/2013 8:16 PM
Buildings in tornado-prone areas should be constructed to withstand strong winds in the same way that hurricanes are factored into building codes in coastal areas, says a new federal report examining the 2011 killer tornado in Joplin.
New model building code standards are among the 16 recommendations of a 492-page draft report released Thursday by the National Institute of Standards and Technology.
Other suggestions call for new standards on community storm shelters, better public warning systems and improved detection of wind speeds at ground level during tornadoes.
That data could help regulators write new building standards that would save lives and limit the staggering property losses that tornadoes cause in the United States, according to the institute, an agency within the Commerce Department.
Although none of the suggestions will have the force of law at the end of the public comment period Jan. 6, the report aims to start discussions among the local, state and federal officials who could take action.
“The overarching conclusion of our two-year study is that death and destruction from tornadoes can be reduced,” Eric Letvin, the agency’s director of disaster and failure studies, said at a news briefing in Joplin.
On May 22, 2011, an EF5 tornado cut a 7-mile path through the heart of Joplin, injuring 1,000 people and killing 161 others, making it the deadliest single tornado since the United States began keeping official records in 1950.
The storm also did upward of $3 billion in property damage. Some 7,500 homes were damaged or destroyed, as were 553 businesses.
Two days after the storm, the National Institute of Standards and Technology sent a team to Joplin to see what lessons could be learned from the damage done by the record-breaking storm.
In all, the report’s authors interviewed 165 survivors and emergency responders, examined damaged buildings, studied death certificates and did computer simulations.
What they learned was that 84 percent of those killed in Joplin were in buildings at the time and died from blunt force trauma — walls falling on them, flying debris crashing into them.
There were few safe places to hide. There were no community storm shelters in Joplin at the time, and four out of five homes in the storm zone were without a basement.
Victims tried to ride out the storm in their homes, public buildings and businesses that were fully or partly destroyed.
The report said the death toll would have been lower if buildings had been designed to resist tornadoes the way some are built now to weather hurricanes and earthquakes in areas of the country prone to those disasters.
True, few buildings could withstand a tornado at the top of the scale. Joplin’s storm at its worst was said to be an EF5.
But a report released earlier this year by the American Society of Civil Engineers reached similar conclusions to the federal report issued Thursday when it said most of the damage done in Joplin was caused by winds of 135 mph or less, or about the speed of an EF2 tornado. None was caused by EF5 winds, which are in excess of 200 mph, the engineering group said.
Had houses been built with roof ties like those used in hurricane zones, more of them would have survived, that organization said.
Yet except in the case of nuclear power plants, safe rooms and storm shelters, “there are no standards for the tornado-resistant design of ordinary buildings and infrastructure” in this country, the National Institute of Standards and Technology report said.
The agency recommends the development of national standards for the design of tornado-resistant buildings and says those standards should be made part of local building codes.
The report specifically singles out the need to improve standards for big-box buildings, such as the Joplin Home Depot store, where seven people died. Experts told The Star in stories published in 2011 and 2012 that buildings of that type are too dependent on a lightweight roofing system for their structural integrity. When tornadoes rip off those roofs, the walls can collapse.
“There is a need to improve robustness and redundancy” in the design of such buildings, the report said.
Industry officials previously told The Star that the basic design of such buildings is sound — they just need to do a better job of supporting those roof-to-wall systems.
Improvements in residential building designs are also needed, the report said.
The report doesn’t address the financial impact of those suggestions, but Letvin said in the news conference that building new houses to a higher, tornado-resistant standard probably would add 5 to 15 percent to the cost.
A spokeswoman for the National Association of Home Builders said Thursday that the group had not thoroughly reviewed the study and had no immediate comment.
Letvin had no cost estimate for what it would take to make commercial buildings and hospitals better able to withstand storms.
But considering the damage to life and property caused by tornadoes, he said, it would be a wise investment.
“The cost of not implementing some of these recommendations affects community resiliency,” Letvin said.
Among the report’s other recommendations for tornado-prone areas:
• Adopt new uniform national guidelines on how to design and where to locate and operate public tornado shelters.
• Improve design standards for elevators and exits in critical facilities like hospitals to ensure they will operate after a tornado strike.
• Prohibit the use of aggregate, gravel or stone roofing materials on buildings of any height because high winds turn the material into projectiles.
• Develop new standards for clear, consistent and accurate alerts and storm warnings to avoid confusion and reduce the number of false alarms that cause people to resist taking shelter.
The report is atwww.nist.gov.