Featured Research

from universities, journals, and other organizations

Massive tornado onslaught raises questions about building practices, code enforcement

Date:
May 14, 2011
Source:
Oregon State University
Summary:
There is no practical, economic way to build structures that could stand up to the savagery of EF5 tornadoes like those that ripped through the South in late April, experts say, but damage from lesser storms could be reduced by better building practices and better enforcement of existing codes.

The roof blew off this house during the massive April, 2011, tornadoes in the South -- due in part, researchers say, to inadequate connections between the roof trusses and the sidewalls.
Credit: Photo courtesy of Oregon State University

There is no practical, economic way to build structures that could stand up to the savagery of EF5 tornadoes like those that ripped through the South in late April, experts say, but damage from lesser storms could be reduced by better building practices and better enforcement of existing codes.

Researchers with a rapid assessment team supported by the National Science Foundation say that much of the damage could be linked to inadequate connections between building members, especially trusses, roof rafters and walls. And even though modern codes are generally adequate, they said, such codes are not always followed or enforced.

The result last month, one day of which has been called the fifth deadliest day of tornadoes in the nation's history, was 305 tornadoes, three of which were the maximum "EF5" category, that killed at least 326 people and may have caused more than $5 billion in damage.

"We often found inadequate or no connections at critical locations in structures, such as attaching the trusses or rafters to the supporting walls, or sill plate to the foundation," said Rakesh Gupta. He is a professor of wood science and engineering in the College of Forestry at Oregon State University, an expert in wind loading and structural resistance, and was a member of the NSF research team.

"Time and again we've seen that such connections are often inadequate under extreme loading conditions," Gupta said. "For instance, trusses that were just toe-nailed to the walls often failed in the high winds, the roof blew off and that allowed the rest of the building to collapse. And in some cases there were no anchor bolts between the bottom plate and foundation, allowing the whole building to shift off the foundation."

The final report from the assessment team is not yet complete, but early observations pointed not just to building codes, but enforcement of those codes, Gupta said.

"In one town in Alabama, I was told there is no inspection of homes by the city building inspector," he said. "Property taxes are very low, inspection is often inadequate, and sometimes that can result in inadequate construction quality and enforcement."

In many cases with the largest tornadoes, the researchers concluded, no existing codes or even quality construction practices made a difference.

"In an EF5 tornado, we observed that even new buildings built with the latest codes were totally destroyed," Gupta said. "One complex had used hurricane clips on trusses, the code-required nailing of roof and wall sheathing, and anchor bolts every four feet. It was destroyed right down to the concrete slab."

Gupta said that it would be possible to build structures that might resist an EF5 tornado, but not economically feasible.

"We could design a wood-frame house which would resist such forces, but who will pay for it?" he said.

Another part of the issue, researchers said, is that the more routine steps which can be taken to prevent greater storm damage are often easy and fairly inexpensive when a structure is being built, but comparatively expensive and difficult to do in retrofitting existing structures.

"When homes are under construction, the reality is that people are more interested in what they are spending on deluxe kitchen countertops and hardwood floors than some foundation bolt they never see," Gupta said. "The things it takes to improve structures and make them more safe are usually hidden behind the walls."

The team also observed that "safe rooms" designed with special construction features to provide refuge during severe storms may only work if a structure is of adequate size. On small houses or other buildings, the entire structure may be blown away and there is no safe place.

The research team will later compile its findings in a full report. Team members were from OSU, the University of Florida, University of Alabama, South Dakota State University, and some private industry agencies.


Story Source:

The above story is based on materials provided by Oregon State University. Note: Materials may be edited for content and length.


Cite This Page:

Oregon State University. "Massive tornado onslaught raises questions about building practices, code enforcement." ScienceDaily. ScienceDaily, 14 May 2011. <www.sciencedaily.com/releases/2011/05/110513091636.htm>.
Oregon State University. (2011, May 14). Massive tornado onslaught raises questions about building practices, code enforcement. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2011/05/110513091636.htm
Oregon State University. "Massive tornado onslaught raises questions about building practices, code enforcement." ScienceDaily. www.sciencedaily.com/releases/2011/05/110513091636.htm (accessed October 23, 2014).

Share This



More Earth & Climate News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

San Diego Zoo's White Rhinos Provide Hope for the Critically Endangered Species

Reuters - Light News Video Online (Oct. 22, 2014) — The pair of rare white northern rhinos bring hope for their species as only six remain in the world. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
Trick-or-Treating Banned Because of Polar Bears

Trick-or-Treating Banned Because of Polar Bears

Buzz60 (Oct. 21, 2014) — Mother Nature is pulling a trick on the kids of Arviat, Canada. As Mara Montalbano (@maramontalbano) tells us, the effects of global warming caused the town to ban trick-or-treating this Halloween. Video provided by Buzz60
Powered by NewsLook.com
Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) — He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) — The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins