More extensive use of precast concrete components, which are fabricated off-site and then connected on-site, could allow bridges to be constructed more rapidly. The increased use of precast components in bridges also promises to increase work-zone safety and reduce environmental impacts for bridges that span waterways.
This report discusses precast concrete systems that have been used for rapid bridge construction outside of Washington State and evaluates whether they are suitable for use within Western Washington.
The report also identifies key features that are important for successful precast concrete system applications. Information on previously used systems was gathered through an extensive review of published literature. Washington State Department of Transportation (WSDOT) design and construction engineers, precast concrete producers, and bridge contractors were also consulted to obtain their input on the positive and negative aspects of applied systems.
Most applications have been used in areas of low seismic potential. By contrast, Western Washington is subject to strong earthquakes. Because precast systems contain connections, and connections are typically vulnerable to seismic loading, a qualitative evaluation of the expected seismic performance of each system was deemed necessary.
The researchers identified four types of precast concrete superstructure systems: full-depth precast concrete panels, partial-depth precast concrete panels, prestressed concrete multibeam superstructures, and preconstructed composite units. The four systems appear to have acceptable seismic behavior, but there are concerns associated with constructability and durability.
Precast concrete substructure systems have received much less attention than have superstructure systems. The use of precast substructure components can provide significant time savings by eliminating the time needed to erect formwork, tie steel, and cure concrete in the substructure. The success of the system depends strongly on the connections, which must have good seismic resistance, have tolerances that allow easy assembly, and be suitable for rapid construction.