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Speeding up the fast lane

Eric Matsumoto
Eric Matsumoto
Faster bridge building may be on the way for California. Civil engineering professor Eric Matsumoto, along with researchers from UC San Diego and state departments of transportation including CalTrans, is exploring the feasibility of constructing bridges in earthquake-prone regions using precast concrete.

The research focuses on a precast bridge element called the bent cap, which connects the bridge girders to columns. It’s an approach to rapid bridge construction already used in some parts of the country.

The research is being funded by a $550,000 contract from the National Cooperative Highway research program.

Using pre-cast concrete eliminates much of the bulky wood forms that currently are usedin California bridge construction. Pre-casting is less labor-intensive at the construction site, Matsumoto says, because it removes the concrete forming, pouring and curing from the work zone increasing safety for both construction crews and motorists, and decreasing traffic tie-ups. “Essentially what it does is speed up construction so there is a reduced impact on the traveling public,” Matsumoto says.

Pre-casting also improves quality and durability, he says, because the work is performed in a controlled environment. “Precast concrete is typically more durable than cast-in-place concrete. It’s built under controlled plant conditions so higher-quality materials, construction techniques and inspections can be employed and there is less impact due to adverse weather conditions,” Matsumoto says.

“What we don’t know is how bridge systems using precast bent caps will behave in a major seismic event,” he says. “But I think the research will successfully develop new systems that will work.” That’s important because California and other states need to replace bridges in congested urban environments by the thousands.

Matsumoto and his students have conducted preliminary oncampus tests for one type of bent cap connection. The new research at Sac State involves more complex beam-column connection tests. Matsumoto’s crew will conduct four of the six beam-column tests.The other tests will take place at UC San Diego, where a large-scale bridge system test will also be performed.


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