Field-Cast Ultra-High Performance Concrete Connections for Prefabricated Bridge Elements and Systems
April 21, 2011
at 2:30-4:00 EST
- UHPC Deck Connections Cyclic Testing at FHWA
FHWA recently completed a test program aimed at assessing the performance of Ultra-High Performance Concrete (UHPC) deck-level connections between prefabricated bridge elements. Read MoreThese full-scale tests on concrete deck subcomponents were completed in the Structural Testing Laboratory at the Turner-Fairbank Highway Research Center as part of the FHWA Structural Concrete Research Program in coordination with Transportation Pooled Fund Project 5(217). This project focused on the performance of 6 inch (150 mm) wide female-female shear key connections containing different types of discrete reinforcement. The testing simulated cyclic service loads and static overloads on both longitudinal and transverse deck-level connections. All of the details investigated performed well. The simplest connection, the non-contact rebar lap splice, had straight lengths of rebar extending 6 inch (150 mm)into the connection from each precast deck element. This video provides an overview of the testing of this particular connection. The test specimen was simply supported and the load was applied adjacent to the connection. Millions of load cycles were applied, including peak loads well in excess of design service loads. In the video, the load is applied and removed 5 times per second. The video also shows that the top of the connection was ponded with water in order to assess watertightness. Watch Video (WMV, 01:11 sec, 6.2 MB)
- UHPC Composite Connections Cyclic Testing
FHWA is currently conducting a test program aimed at assessing the performance of a novel design for the composite connection between prefabricated bridge girders and decks. Read MoreThe connection design engages the advanced mechanical properties of Ultra-High Performance Concrete (UHPC) to simplify the connection and eliminate conflict points between discrete reinforcements. This work is being completed at the Turner-Fairbank Highway Research Center as part of the FHWA Structural Concrete Research Program in coordination with Transportation Pooled Fund Project 5(217). Full scale structural tests are underway to assess the performance of the connection under cyclic loading. This video provides an overview of the two connection designs included in the full scale test, as well as a clip of the cyclic loading. The loading has included over 10 million cycles surpassing the service load for fatigue design of the connection, with over 3 million of those cycles surpassing two times the service load for fatigue design. Watch Video (WMV, 00:56 sec, 4.5 MB)
- Video of Field-Cast UHPC Operations
Lafarge has produced a 3.10 minute video which provides an overview of the operations involved in the construction of field-cast UHPC connections. The video is at the bottom of the page at http://www.ductal-lafarge.fr/wps/portal/ductal/2_2_2-JoinFills
- Full Depth UHPC Waffle Deck Slabs
This video depicts the casting of an UHPC Waffle Bridge Deck Slab for use in the Demonstration Bridge in Wapello County, IA, which will be constructed later this summer. Watch Video (WMV, 03:45 sec, 27.6 MB)
Prefabricated bridge elements and systems (PBES) present many potential benefits to bridge owners and users; however, the need for robust, constructible connections has hindered their application. The use of ultra-high performance concrete (UHPC) to simplify these connection details while simultaneously producing a durable, robust system is garnering significant interest within the bridge community. This is a follow-up to the webinar that was conducted on November 18, 2010, and will provide a more in-depth discussion on the practical applications of using field-cast UHPC connections. The previous webinar can be viewed at http://fhwa.acrobat.com/n134083201011.
UHPC is an emerging technology which presents the opportunity to develop new solutions to existing challenges in the highway infrastructure. UHPC is a fiber-reinforced cementitious composite material with mechanical and durability properties that far exceed those traditionally associated with structural concrete. For example, field-cast deployments of this self-consolidating concrete can expect to achieve 20 ksi or more in compressive strength along with sustained post-cracking tensile strength. To date, this type of concrete has been implemented in five bridge reconstruction projects in three States, and more are on the way.
This session will include a brief overview UHPC and its use as a means to facilitate the use of PBES for Accelerated Bridge Construction, a discussion of successful deployments and promising concepts, and an open discussion among all panel members and session participants.
- Ben Graybeal, Structural Concrete Research Program Manager, Turner Fairbank Highway Research Center, Federal Highway Administration
- Vic Perry, Vice-President & General Manager, Ductal, Lafarge North America