Julio A. Ramirez, associate professor of structural engineering at Purdue, was part of a seven-member, National Science Foundation-sponsored reconnaissance team that traveled to Kobe, Japan, just a few days after the Jan. 17 earthquake. The quake killed 5,250 people and caused more than $100 billion in damage.
"One of the important lessons we learned from Japan is to observe what could happen when a strong earthquake hits a heavily populated area, and especially if that area consists of structures that are of different vintages and different quality of construction," Ramirez says.
The team's report on its trip to Kobe will be published this summer by the Engineering Earthquake Research Center, based at the University of California-Berkeley.
Ramirez, an expert on the design of concrete structures and seismic effects, concentrated primarily on elevated expressways and bridges. He says the majority of the casualties in Kobe occurred in the collapse of wood-framed residential buildings built just after World War II. Their combination of wood frames with few nailed connections, thin walls and heavily tiled roofs was no match for the quake.
In general, he says, the buildings and bridges that suffered the most damage were those built between the end of the war and through the 1970s, when building materials such as steel were expensive and modern building codes were not yet in place. Structures built in the late 1980s and 1990s fared better.
"We have that kind of mix in many areas in America, so the need for retrofitting existing structures is very strong," Ramirez says. "We can't wait for something on the scale of Kobe to happen here and then pay for it. It would be devastating not only economically, but more importantly, in terms of potential loss of life."
Perhaps more important than the buildings and bridges themselves is the need for public education and a comprehensive disaster plan, Ramirez says. For example, the Japanese have been well-drilled in what to do in an earthquake, which may have saved many lives in Kobe. That's not the case in several areas in the United States, Ramirez says.
"Earthquake preparedness is probably the greatest lesson we can learn from the Kobe quake," Ramirez says, "especially in areas like the Midwest that are at high risk."
The New Madrid fault, running through the Mississippi River Valley and named for a town in southeastern Missouri, in 1811 and 1812 caused the strongest earthquakes ever in the contiguous United States.
"We're in an area of high risk for a different reason than California, which has frequent strong earthquakes," Ramirez explains. "It's not that we can't have strong quakes, they just happen less frequently here, which makes people less aware of the dangers. Also, California's quakes have to a certain extent already cleaned up that state's inventory of buildings and bridges through a sort of natural selection, whereas we haven't had that benefit, if you can call it that."
In 1989, damage caused by a strong earthquake in Loma Prieta, Calif., prompted Ramirez and Purdue civil engineering Professor Austin D. Pan to begin a study to examine the condition of the 300 or so older bridges in the southern part of Indiana. The aim was to develop a system to assess the risks the bridges would face in an earthquake and to prioritize them for repair. The project is funded by the Indiana Department of Transportation and the Federal Highway Administration.
For the first phase of the project, the researchers developed a one-of-a-kind computer program that helps state engineers accomplish those tasks. To use the program, an engineer inputs data about the various structural elements of a bridge and then determines how much ground motion the bridge could withstand.
"One of the major hurdles is that we don't have as much actual data on ground motion in this area as they do in California," Ramirez says.
The program was test-run using data from three typical Indiana bridges. The program now is being reviewed by a state maintenance and rehabilitation group, as well as the regional office of the Federal Highway Administration.
Ramirez expects the Indiana personnel to begin using the program this summer.
"Not just anybody can use this program and make these decisions," Ramirez says. "It takes a trained engineer to make those calls. Furthermore, in many cases, the information about these bridges will be unavailable, and engineers will have to go out and examine the bridges."
The Indiana counties in the study are Gibson, Pike, Posey, Vanderberg and Warrick.
In developing the computer program, the Purdue researchers used information gathered from the Kobe and the 1994 Northridge, Calif., earthquakes, such as information about the performance of bridge supports. For example, the arrangement of reinforcing bars inside bridge columns in southern Indiana bridges tends to be very similar to that in the older bridges in Kobe, Ramirez says.
Other states also may be able to use the program, he says.
"California and New York already have procedures to prioritize their bridges, but because they have thousands to evaluate, their first-level screening systems are based more on qualitative, not quantitative, information," Ramirez says. "This computer program would offer them a second, more detailed screening."
What the computer program can't tell you is how to go about fixing any structural deficiencies, Ramirez says. The second phase of the project will entail the repair, replacement or retrofitting of high-priority bridges, a task in which Purdue research and expertise can play a further role, he says.
In addition to the Indiana project, Ramirez and Pan are collaborating with Mete A. Sozen, the Kettelhut Distinguished Professor of Civil Engineering, in a research project sponsored by the National Science Foundation to evaluate the performance of bridge piers during the Northridge quake. The study will provide additional information to improve the seismic performance of bridges in Indiana, Ramirez says.
In another study, Ramirez and his colleagues are testing the strength, durability and performance of a new design system for multiple-span bridges, which Ramirez says could reduce the construction time for some bridges. Instead of just one layer of reinforced concrete, the new design is a combination of two layers: the top is reinforced concrete poured on the site; the bottom consists of 4-foot by 20-foot panels of precast prestressed concrete.
"This type of structure has been used in a few bridges in Louisiana and Florida, but they experienced a lot of cracking and caused concern about its durability," Ramirez says. "Our group was asked to look for solutions to this problem."
The research is funded by the Federal Highway Administration and the Indiana Department of Transportation.
Source: Julio A. Ramirez, (765) 494-2716; Internet, firstname.lastname@example.org
Writer: Amanda Siegfried, (765) 494-4709; Internet, email@example.com
Purdue News Service: (765) 494-2096; e-mail, firstname.lastname@example.org
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