Monday, 16 April 2012

NCSU Constructed Facilities Laboratory tests building structures

We’d all like to think our buildings, roads and infrastructure are here to stay for the long run. At North Carolina State University's Constructed Facilities Laboratory, featured in the NCSU Technician, researchers know it’s only a matter of time before something goes wrong.

Earthquakes, erosion, and even time itself pose a threat to the things we use every day—but it’s the CFL’s job to push these structures to their breaking point to find out how to make them safer for society.

Established in 1996, the CFL boasts a large research complex dedicated to testing large-scale structures under a variety of environmental conditions.

According to engineering professor Rudi Seracino, the CFL employs a variety of techniques to test the integrity of materials and observe how they behave under stress. The seismic shake-table test uses a massive platform to simulate the conditions of an earthquake. Researchers can use the large-scale static test to apply a load at a slow rate until the structure fails.

However, catastrophic events aren’t the only things that can damage a material. Continuous everyday stress can cause damage, such as wind or cars driving over a bridge. In those cases, researchers use fatigue tests to simulate the real-life wear-and-tear a structure will go through over millions of cycles—the goal of this is to approximate the life span of a structure.

Many companies have already shown great interest in the CFL, and continue to do so. Sami Rizkalla, Mervyn Kowalsky and Rudi Seracino are researchers at the CFL’s structural engineering department. Their work has been consistently supported by government agencies such as the North Carolina Department of Transportation and privately-owned corporations like Progress Energy.

“We test the materials until they fail to learn more about how they work,” Rizkalla said. Learning about the way a structure behaves under stress is essential to learning how to improve it.
Rizkalla, a professor of civil engineering, conducts research with concrete structures. He is also researching an advanced fiber-reinforced polymer material and how it can be used on existing structures to strengthen and repair them. Rizkalla’s research aims to examine the behavior of large-scale structures in order to assess the safety of those structures.

Safety is an important aspect at the laboratory, and many of the current research projects are connected to the idea of better-preparing infrastructure for failure.

Civil engineering professor Mervyn Kowalsky is particularly interested in earthquake engineering research, focusing on the design of bridges to improve their safety during large-scale seismic events. Several of Kowalsky’s research projects are currently supported by the state of Alaska to improve the safety of the construction of bridges in the region.

One of the aspects Kowalsky’s research is working to improve is a method for constructing bridges. One bridge construction method involves driving large, hollow steel pipes into the ground. The pipes are then welded to beams to form the bridge supports. This is potentially dangerous, as the welding can become brittle and fail catastrophically during an earthquake. Kowalsky aims to replace this welding technique with a safer design that will force potential damage away from the welded connection.
In addition to improving the bridge’s safety, Kowalsky also aims to improve the efficiency and longevity of the bridges. For example, a lot of money is spent each year rebuilding structures that have failed. Instead of rebuilding an entire structure, part of Kowalsky’s research is concerned with repairing these structures to force future damage to another area of the structure.

“Safety is the most important thing to me,” Rizkalla said. “Paying close attention to the safety of a structure can save lives.” Read More.

No comments: