September 27, 2002
Engineers will use new lab to design better structures, materials
WEST LAFAYETTE, Ind. Purdue University's new large-scale civil engineering laboratory will be a sophisticated facility in which engineers and scientists from diverse fields will work together on a wide range of projects.
However, one of its key advantages can be traced to a simple fact: small-scale models are not as good as the real thing.
Civil engineers need a large facility for certain types of research because models and computer simulations alone are not sufficient to demonstrate how structures will perform in real-life situations, said Robert Frosch, an associate professor of civil engineering who was involved in the facility's planning.
"We have found that there is a size effect in which, as something gets larger, its strength actually goes down," he said. "So what we thought was safe at the small scale doesn't actually translate upwards to the large scale."
In addition to its role in large-scale testing, the Robert L. and Terry L. Bowen Laboratory for Large-Scale Civil Engineering Research also will be used to study smaller specimens to develop superior asphalts and concretes for roads and bridges.
"The new lab will be much more flexible than our current lab," said Julio Ramirez, a professor of civil engineering who chaired the planning committee for the lab. "We will be able to change the configuration of equipment to suit specific research."
The work is likely to involve extensive collaborations among researchers in fields ranging from electrical to aeronautical engineering, and civil engineering to computer science, he said.
Frosch's research includes testing new types of corrosion-resistant materials for bridges. The lab will enable him to test various designs before actually using the materials in a real bridge.
"We can't build 20 bridges out there and say, let's try this, this and this," he said. "That's where the big lab comes in."
Engineers will use the lab to validate calculation procedures that have been developed for simulations that attempt to "scale up" theoretical models for use in larger, real-life designs.
"We can sit down at the computer and punch in a bunch of numbers and equations and write some really exciting computer code, but until we calibrate those models or make sure they work properly they will have limited use in engineering practice," said Jason Weiss, an assistant professor of civil engineering. "Current developments in the field of embeddable sensors and performance simulation are opening a new world of opportunity for us to create infrastructure that can 'tell us' how it is responding, thereby allowing us to improve design, maintenance and repair strategies based on 'real-world' feedback."
The lab will provide space for sophisticated large scale environmental chambers that can be used to simulate conditions ranging from dry, arid regions of the world to cold-weather climates. The chambers will be used for research to create both newer, higher performance materials and models to describe their long-term performance.
"We will be able to simulate environments more accurately and on a much larger scale than we do with the chambers we currently have," Weiss said. "We want to eventually use the lab to house chambers that can simulate a wide range of environmental conditions, including cyclic cold weather conditions, salt-spray conditions, such as those seen on bridges and dams, and rapid-drying conditions seen in desert environments. This will enable our simulation models to be verified under conditions that are more like the real world, thereby increasing the opportunity for our research to have an immediate impact on the engineering profession."
Dulcy Abraham, an associate professor of civil engineering, plans to use the lab for work in trenchless technology.
"Trenches are the most common way of laying sewers," she said. "But there are lots of problems with trenches. If you have a roadway in the path, you have to cut through the roadway, which is not a desirable situation. In some cases you may not want to do open trenching for safety reasons or for environmental reasons. So there is a family of technologies that exist that are called trenchless technologies. This does not mean there are no trenches. But the amount of trenching required is greatly minimized."
Special machines are used for tunneling and for replacing and repairing damaged pipes. The machines make it possible to carry out the work without digging extensive trenches.
In addition to work in trenchless technologies, Abraham also plans to use the new lab for research that studies how different types of pipes stand up to various environmental and soil conditions.
Other civil engineers want to use the lab to study how the connections between steel beams and columns are affected by repeated stresses from earthquakes and high winds.
"Earthquakes and wind loading cause the building to deform laterally," said Judy Liu, an assistant professor of civil engineering. "That causes the connections to rotate and cycle back and forth, and this affects how the whole structure behaves."
Even if the movement of a building's steel structure does not pose safety concerns, it does cause potentially damaging interactions between the structure and nonstructural elements, such as partitions. The movement also can damage electrical, plumbing, heating and air conditioning systems. The large lab will give researchers the ability to test structures and analyze how systems and partitions are affected.
"The new lab certainly will offer more flexibility in terms of being able to do larger scale testing to see interactions between elements within buildings," Liu said.
Engineers also might use the lab to test how well structures are able to withstand a bomb blast.
The facility will provide computerized linkups so that engineers around the world will be able to participate in research remotely.
"You will be able to go to a Web site, review the data, talk to people there like having a conference with a camera on your computer," Ramirez said. "You have to be able to interact and look at the data and then decide how to modify the experiment."
The new lab will play an important educational role as well. Both graduate and undergraduate students will participate in research in the lab. Lessons learned by researchers will be integrated into engineering curricula and used to educate future generations of engineers.
"I think the key is that this is a research facility, but undergraduates and graduates can do research and should do research in the facility," Ramirez said. "One of the primary reasons we do research at universities is to educate the people who will be doing this work in the future."
The lab will be helpful for engineers designing "pre-cast" portions of buildings. Instead of pouring concrete at construction sites, building structures are cast at another location and later trucked to the site for assembly.
"Whenever you build something that is pre-cast, you're building it with components that have to be connected, and the connections between those components become critical when there is an earthquake," Ramirez said. "What we are interested in is, is there a connection that we can develop that will perform satisfactorily in an earthquake?"
Writer: Emil Venere, (765) 494-4709, firstname.lastname@example.org
Sources: Julio Ramirez, (765) 494-2716, email@example.com
Robert Frosch, (765) 494-5904, firstname.lastname@example.org
Dulcy Abraham, (765) 494-2239, email@example.com
Judy Liu, (765) 494-2254, firstname.lastname@example.org
Jason Weiss, (765) 494-5025, email@example.com
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