In the last decade, three important new bridges in the Portland area were the subject of intense discussion and analysis: the Tilikum Crossing, the Sellwood Bridge and the Columbia River Crossing. One of those bridges is completed, the second is under construction and the third one was canceled.
As a Metro Councilor, Robert Liberty was involved in the decision making process for all three projects. The way in which those projects were analyzed and presented to the public revealed to him a great deal about the many weaknesses in the way we make major transportation investment decisions. Those insights are the topic of his seminar presentation.
Robert Liberty has more than a third of a century's experience with the...Read more
During Hurricanes Ivan in 2004 and Katrina in 2005, at least 11 highway and railroad bridges along the U.S. Gulf Coast were damaged. When the water rose during the storms, wave forces slammed into the bridges’ supporting substructures, and when it rose high enough, the water’s buoyancy had enough power to lift off sections of a bridge’s superstructure and lay them aside like giant Legos.
To build bridges that can withstand the force of hurricane waves, engineers must be able to estimate the effects those waves will have on bridge structures. An OTREC project led by Oregon State University professor Daniel Cox examined the effects of wave loading on highway bridge superstructures.
Cox and co-investigator Solomon C. Yim, also of Oregon State University, conducted experiments in the Large Wave Flume at the O.H. Hinsdale Wave Research Laboratory at Oregon State University. They used a 1:5 scale, reinforced concrete model of a section of the Interstate 10 Bridge over Escambia Bay, Fla, which failed during Hurricane Ivan.
The problem addressed by this project is that, while...Read more
Oregon Institute of Technology students got an up-close look at bridge engineering on a large scale during a trip to the Mount Shasta area Sept. 28. A group of 16 students and faculty members Roger Lindgren and Matthew Sleep from the civil engineering department visited the Antlers Bridge Replacement construction site. The trip was organized by Oregon Tech’s Institute of Transportation Engineers student chapter with funding provided by OTREC.
Eric Akana, P.E., of the California Department of Transportation hosted the tour with CalTrans engineers Shari Re, Bill Barnes, and Mark Darnall.
The new Antlers Bridge, which spans the Sacramento River arm of Lake Shasta near the town of Lakehead, California, will be a balanced cantilever cast-in-place concrete bridge. The new bridge will consist of five spans coming together to make a 1,942-foot structure, approximately 600 feet longer than the original Antlers Bridge. The new bridge will replace an aging steel structure that is reaching the end of its service life. In addition, a section of highway south of the bridge will be realigned because of a high accident rate.
The Oregon Tech group met with CalTrans engineers for an extensive project review presentation at the field office and then proceeded to the construction site where they spent over two hours viewing foundation preparation, pier construction, pier-table form travelers, and abutment work.
In addition to viewing construction details and...Read more
It’s not shocking that bridges built without thought to earthquakes wouldn’t make it through a big quake unharmed. More surprising, however, is how much damage even a relatively small earthquake would cause to Oregon’s bridges.
In an exhaustive OTREC project, researcher Peter Dusicka looked at the most common bridge types in the Oregon highway system. Those bridges weren’t just fragile, he found—they were even more fragile than other researchers and technical guidelines had suggested.
Dusicka published his preliminary findings in a draft report last year. The final report, “Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network,” is out now. Click here to download.
Most Oregon highway bridges were built before the 1980s, when designers started to consider seismic activity. Dusicka set out to see what would happen to the most common bridge type, continuous concrete multi-beam or girder, during quakes of varying degrees.
To find that out, he had to first know how the ground in the Pacific Northwest moves during and earthquake and second, model how the bridge type would react to these motions. Historical and geological evidence show a catastrophic earthquake will occur sooner or later in the region, Dusicka has said, as the Cascadia subduction zone stores up energy that...Read more
A major seismic event is predicted to hit the Oregon Coast any year now, which has transportation planning experts asking, “Is Oregon prepared?”
OTREC seismic expert and Portland State University Associate Professor of Civil and Environmental Engineering Peter Dusicka recently spoke at a May 13 symposium titled, Next Big Earthquake In Oregon: Are We Ready? Along with five other PSU professors, the Maseeh College-sponsored symposium addressed the state’s preparedness in terms of emergency response and infrastructure. Dusicka’s talk focused on the ability of Oregon’s bridges to perform in a major earthquake.
“We depend on our network of bridges for anything from immediate emergency response to transportation of goods and services,” Dusicka said. “There is no doubt that there is an inventory (of bridges) within Oregon of a certain vintage where we know there will be issues.”
The ability of a bridge to withstand a seismic event can depend on the type of bridge, when it was constructed and how it’s supported in terms of a foundation, Dusicka said. OTREC recently worked with ODOT to examine several hundred bridges in Oregon for seismic deficiency. The most telling trait, Dusicka said, is age.
“Over time, we’ve learned the ways we’ve designed and built bridges are not the best for resisting earthquakes,” Dusicka said. “The challenge with remediation today is, do we have the knowledge to do this effectively, and if we do, do we have the funds to execute...Read more
As a student at the University of British Columbia, Peter Dusicka pursued earthquake engineering in part because so few others had taken that path. “I was looking for a way to make a difference and looking for areas within civil engineering that seemed immature,” Dusicka said.
There was too much guesswork as to how well the Pacific Northwest’s transportation network would handle the type of subduction zone earthquakes the region is prone to. Now, thanks in part to Dusicka’s research, we know a lot more.
When it comes to the fragility of Oregon’s transportation system, the recent earthquakes around the Pacific Rim provide more insight into a major quake than do models developed for North America, said Dusicka an OTREC researcher and Portland State University associate professor. “The subduction zone earthquake in Oregon, Washington and British Columbia isn’t a threat anywhere else in the U.S.,” he said.
The recent Japanese quake as well as the one in Chile—both subduction-zone quakes—are more instructive. Subduction-zone quakes tend to be larger magnitude, shake longer and affect a larger geographic area than other earthquakes.
The serious earthquake related damage in Japan probably would have been worse had that country’s leaders not been spurred by the 1995 Kobe earthquake. “The Japanese people and...