Focus on Research
Penn State Intercom......March 15, 2001

Engineers discover new methods
to protect against windstorm damage

By Curtis Chan
College of Engineering

According to a recent engineering study, the "sacrificial ply" glazing system is the safest, most economical way to save lives and protect property where architectural glass windows are employed in windstorm-prone areas.

The study team, consisting of Richard Behr, professor and head of architectural engineering; Paul Kremer, research associate in architectural engineering; and Joseph Minor, research professor at the University of Missouri-Rolla's Graduate Center for Materials Research, came to its conclusion after examining buildings in areas devastated by hurricanes and conducting extensive laboratory tests.

In the "sacrificial ply" glazing system, two plies of glass are laminated to a thin, clear plastic sheet to produce a laminated glass window unit. During a hurricane or tornado, the outer, exterior-facing glass ply is sacrificed to the impact of flying debris, while the inner glass ply and weather seal around the glass perimeter is preserved, thus protecting the building and its occupants. Many manufacturers currently make laminated glass and the sacrificial ply laminated glass can be installed in many commercially available window frames.

"We concluded that the majority of damage didn't come from high wind pressures as many building designers originally thought, but from windborne debris im-pacts," Behr and Minor said. "It's costly to repair buildings. We saw entire building facades without glass, which allowed wind and rain to ruin the entire building interior. What's worse is that some of those businesses had to shut down for months. It was a huge economic loss in terms of productivity."

In addition to studying damage in the wake of hurricanes, including 1992's Hurricane Andrew, the team developed computer models and tested laminated glass to check models and prove the sacrificial ply design concept. They simulated flying debris by launching wooden 2x4s (representing large objects) and steel ball bearings (representing small objects) at samples of laminated glass, using compressed air cannons.

"We started at low velocities and kept incrementing until we reached failure in the inner glass ply," Kremer explained. "We're using the data and developing design tables and curves that supplement the current procedure designers use when choosing glass to handle wind loads. Now they will have quantitative information that lets them take into account windborne debris in the design process."

Although it is not currently mandated by building codes, Kremer said the concept offers a promising option for building designers.

"We are very optimistic that our sacrificial ply research will significantly enhance the hurricane resistance of windows in buildings," Behr said.

Penn State Erie students initiate
treaty research, establish database

Nine political science students at Penn State Erie, with support from Professor John Gamble, have developed a statistical database that includes more than 6,000 multilateral treaties from 1648 to 1995.

Three of those students will have their first professional paper, based on knowledge gleaned from the database, published this fall.

Gamble, professor of political science and international law, started the ball rolling last year, when he completed a review of Christian Wiktor's Multilateral Treaty Calendar, 1648-1995, for the American Journal of International Law. He found the book to be the most comprehensive record ever compiled of multilateral treaties, and it occurred to him that with a lot of effort, it could become a unique research resource. By the fall of 1999 he had a group of students ready to undertake the effort. Not only were they ready to work on the database, they asked Gamble to teach a course on treaties concurrent with their database work.

Political science majors and Penn State Schreyer Scholars Jared Hawk of Kittanning and Teresa Bailey of Belfast, N.Y., headed up the database team, which included nine other students. Hawk said the hardest part of creating the database was developing the framework that would make it searchable.

The students who created the database signed up for shifts and worked every day in a room at the library. The database was complete by the end of the spring 2000 semester, and Bailey spent the summer doing a final quality check. Erin McCurdy of Erie, another political science major, decided to use the database as part of her work on an independent study course that examined human rights treaties. At Gamble's suggestion she collaborated with Hawk and Bailey, and the result was a paper co-authored by Gamble, Bailey, Hawk and McCurdy titled "Human Rights Treaties: A Suggested Typology, An Historical Perspective," which will be published this fall in the Buffalo Human Rights Law Review.

Center focuses on enabling
buildings to withstand blasts

With the aid of a two-year, $3.51 million contract from the U.S. Army Corps of Engineers, the University has established a Protective Technology Center to develop methods to ensure the safety of U.S. government and military personnel and facilities under terrorist bomb threat.

Theodor Krauthammer, professor of civil engineering, is director of the new center. He is a specialist in the study of the survivability and fragility aspects of facilities subjected to blast, shock and impact.

About 30 faculty members, technical support staff members and students will be associated with the new center, which will be the largest of its type in the United States.

"We're going to perform research on a broad range of areas related to the problem, including issues related to blast, the behavior of buildings and materials, and computer simulations of pre- and post-explosive event building conditions," Krauthammer explained.

Stone bridges
rated for soundness

A new rating system, developed by a University engineer, can help to ensure safety in the continued use of masonry arch bridges built in the 19th century.

About 1,000 road bridges built in the 1800s and early 1900s are still in use today in the United States and an additional 2,000 are still in use for rail. These structures are either difficult to rate for capacity or are unrateable with the currently available techniques, said Thomas Boothby, associate professor of architectural engineering.

Using Boothby's system, bridge owners and their consultants can evaluate a stone bridge in the span direction with a level of sophistication, accuracy and speed comparable to the techniques used for steel and concrete bridges. Boothby noted, "Basically, the technique calculates the stresses in the bridge and compares them to the assessed capacity of the materials."

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