Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Increase in storm damage brings call for more stringent standards

09.08.2011
The NSF report this story is based on is available online: http://bit.ly/pZnizp

Researchers from a team funded by the National Science Foundation have examined some of last spring’s massive tornado damage and conclude in a new report that more intensive engineering design and more rigorous, localized construction and inspection standards are needed to reduce property damage and loss of life.

As one of the nation’s most destructive tornado seasons in history begins to wane, and hurricane season approaches its peak, experts are working to determine if old, tried-and-true approaches to residential and small building construction are still adequate, or if it’s time to revisit these issues.

“Modern building codes are not what we would call inadequate, but they are kind of a bare minimum,” said Rakesh Gupta, a professor of wood engineering and mechanics at Oregon State University, and one of the members of the NSF team that traveled to such sites as Tuscaloosa, Ala., and Joplin, Mo. – where a massive EF5 tornado in May killed more than 150 people and caused damage approaching $3 billion.

“Beyond that, in the actual construction process, buildings are often not built precisely to codes, due to inadequate construction work or code enforcement,” he said. “We can do better. The damage didn’t have to be as bad as it was. We can design and build structures more rigorously that could withstand wind forces up to 140-150 miles per hour, which would help them better resist both tornadoes and hurricanes.”

In their research, the scientists and engineers found that even in the most catastrophic tornadoes, the path exposed to the most extreme winds is very narrow. In the Joplin example, buildings less than one-half mile away probably faced winds in the 130 mph range, which often destroyed them because they lacked appropriate fasteners, tie-downs, connectors, or adequate number of sheathing nails.

“Another thing we need to consider more in our building practices is the local risks and situation,” said Arijit Sinha, an OSU professor in the Department of Wood Science and Engineering.

“Just as cities like San Francisco adapt their building codes to consider earthquake risks, many other towns and cities across the nation could be creating local codes to reflect their specific risks from hurricanes, tornadoes, high winds or other concerns,” Sinha said. “A national building code may be convenient, but it isn’t always the best for every single town in the country.”

Among the findings of the new report:

It’s not possible to economically design wood-frame structures that could resist damage from the highest winds in extreme tornado events, such as EF4 or EF5, but irreparable damage from lesser winds could and should be reduced.

Tornadoes and hurricanes apply different types of forces to buildings, and what will adequately protect from one type of storm event isn’t identical to the other. Implementing hurricane-region construction practices in a tornado-prone region is a good start, but not an end solution.

Vertical uplift, one of the special risks from tornadoes, is often not planned for in traditional construction approaches.

Interior closets and bathrooms can provide some protection at lower wind speeds, but more consideration should be given to construction of “safe rooms” that can save lives in major events.

Cost will always be an issue in either new construction or retrofitting of existing structures to better resist these violent storms, the researchers said, but in new construction some of the costs are fairly modest. Thicker plywood sheathing, closer stud spacing such as 12 inches on center, tighter nailing schedules, and more consistent use of inexpensive metal connectors such as “hurricane ties” and anchor bolts could accomplish much to improve safety and reduce damage, Gupta said.

Retrofitting of existing homes is much more costly, but still something many homeowners should consider, he said. And although tornadoes and hurricanes have different types of impacts on buildings, the wind speeds of a moderate tornado and major hurricane are similar.

Even where cities and towns don’t have more stringent building codes, Sinha said, individuals can and probably should have their blueprints or structures reviewed by licensed engineers to plan adequately for damage from hurricanes, tornadoes, earthquakes or other extreme forces.

For reasons that are not clear, 2011 has been one of the most destructive tornado years in history, even in regions of the Midwest and South that experience these storms with regularity.

One of the largest outbreaks of severe weather in U.S. history occurred on April 27, including a tornado that hit Tuscaloosa County in Alabama, destroying or severely damaging 4,700 homes. The new report was based on lessons learned from that event.

The report was done by a study team supported by the National Science Foundation and the International Associations for Wind Engineering that included researchers from OSU, the University of Florida, University of Alabama, Applied Technology Council, South Dakota State University, and private industry.

About the OSU College of Forestry: For a century, the College of Forestry has been a world class center of teaching, learning and research. It offers graduate and undergraduate degree programs in sustaining ecosystems, managing forests and manufacturing wood products; conducts basic and applied research on the nature and use of forests; and operates 14,000 acres of college forests.

Video of the damage in Joplin, Mo., is available online, both on YouTube and in a high resolution format:

YouTube: http://youtu.be/T6CboNmIqAY
High Resolution: http://youtu.be/T6CboNmIqAY?hd=1

Rakesh Gupta | EurekAlert!
Further information:
http://www.oregonstate.edu

More articles from Architecture and Construction:

nachricht Smart buildings through innovative membrane roofs and façades
31.08.2017 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP

nachricht Concrete from wood
05.07.2017 | Schweizerischer Nationalfonds SNF

All articles from Architecture and Construction >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>