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Fully Precast Bridge Bents for Use in Seismic Regions
Slide 1 Fully Precast Bridge Bents for Use in Seismic Regions
Slide 2 What It Is
The innovation consists of a totally precast concrete bridge bent system, including precast columns and beams. A bridge bent is the same as a pier. It supports the girders and deck of the bridge. A pile is driven into the ground and a "footing" is typically placed on top of several of them very close together. Once the footing is in place, the bent can be constructed on top of the footing.
To construct precast elements in high seismic zones requires ductile detailing which permits the structure to deform rather than have a sudden unexpected brittle failure. The connections are made with a small number of large-diameter reinforcing bars that are grouted into larger-diameter ducts. This will be the first project in the U.S. to use precast, segmental construction for bridge bents in high seismic regions.
Slide 3 Details to be considered
Control connections will be cast as shown in a-c. Test connections will have solid bents with the connection at the top of footing and above the footing, d-e. Hollow bents, f-g, will be tested and bent-to-drilled shaft connection will be tested, h.
Slide 4 Need for Innovation
Slide 5 Anticipated Advantages to Conventional Practice
Slide 6 Project Deliverables
Guidelines, examples and specifications will be developed from which engineers will design and construct a bridge in Washington State. The specifications will be included in Washington State's Bridge Design Manual and be presented to the American Association of State Highway Transportation Organization Technical Committee to be adopted as a Guide Specification for Seismic Design of precast construction.