Project # NCTRME
- Marc Eberhard, Professor, University of Washington (PI)
- John Stanton, Professor, University of Washington (Co-PI)
- Claudia Ostertag, Professor, UC Berkeley
- Olafur Haraldsson, Graduate Research Assistant, University of Washington
- Todd Janes (MSCE 2011), University of Washington
- Phillip Davis (MSCE 2011), University of Washington
- Gunnsteinn Finnsson, Graduate Research Assistant, University of Washington
In comparison with traditional cast-in-place construction of bridges, precast construction offers the benefits of reducing traffic congestion in urban regions and reducing the length of time that workers are exposed to roadway hazards. Over the past 50 years, thousands of bridge girders have been precast throughout the United States. Other bridge components have also been precast in regions with low seismicity. In contrast, nearly all bridge columns and crossbeams in seismic regions are still constructed with cast-in-place concrete. As congestion increases on urban highways, bridges in seismic regions must be designed not only to perform well during earthquakes, but also, they must be designed to be constructed rapidly.
With the support of PEER, the Washington State Department of Transportation, the Transportation Northwest Regional center (TransNow), and the Federal Highway Administration, PEER researchers have developed a precast system that is easy to construct and is expected to perform well during earthquakes. WSDOT deployed this precast system on a bridge overpass over I-5 in the Spring of 2011, as shown in Figure 1.
The current PEER project will build on this previous research to develop a new bent system in which the precast columns are pretensioned, as shown in Fig. 2. The addition of pretensioning to the system introduces a self-centering force that will return the bridge to its original position following an earthquake, so that it can function immediately.
The current phase of the project is evaluating the benefits of incorporating Hybrid Fiber-Reinforced Concrete (HyFRC) and stainless steel in the plastic-hinge regions.
The main outcome of the previous research has been the bridge that was constructed over I-5, which is shown in Figure 1. References associated with that bridge include:
- Khaleghi, B., Schultz, E., Seguirant, Seguirant, Marsh, M.L., Haraldsson, O.S., Eberhard, M.O. and Stanton, J.F. (2012). “Accelerated Bridge Construction in Washington State — From Research to Practice,” PCI Journal, Preacast/Prestressed Concrete Institute, Fall, pp. 34-49.
- Haraldsson, O.S., Janes, T.M.*, Eberhard, M.O., and Stanton, J.F. (2012). “Seismic Resistance of Socket Connection between Footing and Precast Column,” accepted for publication in Journal of Bridge Engineering, ASCE, pp.
- Pang, B.K., Eberhard, M.O., and Stanton, J.F. (2010), “Large-Bar Connection for Precast Bridge Bents in Seismic Regions,” Journal of Bridge Engineering, ASCE, May-June, pp 231-239.
- Steuck, K., Stanton, J.F. and Eberhard, M.O. (2009), “Anchorage of Large-Diameter Reinforcing Bars in Ducts,” ACI Structural Journal, July-August, pp 506-513.
- Pang, J.B.K., Steuck, K.P., Cohagen, L.S., Eberhard, M.O. and Stanton, J.F. (2008), “Rapidly Constructible Large-Bar Precast Bridge-Bent Connection,” Washington State Department of Transportation Draft Report, WA-RD 684.2, Olympia, Washington, October, 184 pp.
- Steuck, K.P., Pang, J.B.K., Eberhard, M.O. and Stanton, J.F. (2008), “Anchorage of Large-Diameter Reinforcing Bars Grouted into Ducts,” Washington State Department of Transportation Report, WA-RD 684.1, Olympia, Washington, July, 148 pp.
This phase of the PEER support will result in the following outcomes:
- Design details for precast, pretensioned bridge columns
- Measurement and observations of the response of the top and bottom connections to cyclic lateral loading
- Experimental evaluation of the benefits of using HyFRC and stainless steel.
- OpenSees models that have been validated from test data to estimated the displacements of column following an earthquake.
The deployment of a rapidly constructible system with excellent seismic performance (including low residual displacements and minimal damage succeptibility) would have a large impact on the post-earthquake functionality of highway transportation systems. Such a system would also be a good candidate to support high-speed rail systems, which are particularly sensitive to changes in rail alignment.