Segmental bridge
A bridge segment in Dallas, Texas, USA.
Ancestor	Box girder bridge
Related	Precast Segmental Bridge
Descendant
Carries	Traffic
Span range	Long
Material	Concrete
Movable	No
Design effort	High
Falsework required	Yes

As its name implies, a segmental bridge is a bridge built in short sections (called segments), i.e., one piece at a time, as opposed to traditional methods that build a bridge in very large sections. The bridge is made of concrete that is either cast-in-place (constructed fully in its final location) or pre-cast (built at another location and then tranported to their final location for placement in the full structure). Jump to: navigation, search Aerial view of Dallas City nickname: Big D Location Location in the state of Texas Government Counties Dallas County Collin County Denton County Kaufman County Rockwall County Mayor Laura Miller Physical characteristics Area      Land      Water 385. ... A box girder bridge is a bridge commonly used for roadway flyovers and for modern elevated structures of light rail transport. ... Jump to: navigation, search A log bridge A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. ... Placing a concrete floor for a commercial building Installing rebar in a floor during a concrete pour In construction, concrete is a composite building material made from the combination of aggregate and cement binder. ...

The first segmental concrete bridge, built in 1950, was cast-in-place across the Lahn River in Balduinstein, Germany. The first precast segmental concrete bridge, built in 1962, crossed the Seine River, France. (FHWA 2003) The first U.S. precast segmental concrete bridge, built in 1973, was built in Corpus Christi, Texas. (LoBuono 2005) The first U.S. cast-in-place segmental bridge, built in 1974, was built near San Diego, California.

These bridges are very economical for long-spans (over 100 meters), especially when access to the construction site is restricted. They are also chosen for their aesthetic appeal.

Segmental bridge under construction, Ft. Lauderdale, Florida, USA.

The sequence of construction is similar to traditional concrete bridge building, i.e., build the support towers (columns), build the temporary falsework, build the deck, perform finish work. The principle differences are as follows: Jump to: navigation, search Image File history File links SegmentalBridgeFtLauderdale. ... Jump to: navigation, search Image File history File links SegmentalBridgeFtLauderdale. ...

1. The support towers may be built segmentally. Often this is accomplished using "slip-form" construction, where the falsework moves (slips) upward following sequential concrete "pours." The falsework uses the newly constructed concrete as the basis for moving upward.
2. After the towers are built, a superstructure is built a top the towers. This superstructure serves as the "launching" point for building the deck. (The deck is often built in both directions away from the tower, simultaneously.)
3. The deck is now constructed sequentially, beginning at the tower, one section at a time.
   • In cast-in-place bridges, the falsework is connected to the previously installed concrete and allowed to cantilever freely. Next, the permanent reinforcing steel and supports are installed. Finally, the concrete is placed and cured, freeing the falsework to be moved.
   • In pre-cast bridges, the concrete segment is constructed on the ground, and then transported and hoisted into place. As the new segment is suspended in place by the crane, workers install steel reinforcing that attaches the new segment to preceeding segments. Each segment of the bridge designed to accept connections from both preceeding and succeeding segments.
4. The process in step 3 is repeated until the span is completed.

References

LoBuono, J. (2005). "Assembly required-The instructions for building New Jersey’s first segmental bridge." Chicago, Illinois: BridgesMagazineOnline.com. September/October. Downloaded November 2, 2005 from http://www.bridgebuildermagazine.com/.

FHWA (2003). "Task 15.2 Research Synthesis Statement: Segmental Concrete Bridge Design and Construction Practices." Washington, D.C.: Federal Highway Administration. Downloaded November 2, 2005, from http://www.fhwa.dot.gov/BRIDGE/segmental/task152.htm.

Related sites

• http://www.fhwa.dot.gov/bridge/segmental/index.htm
• http://www.asbi-assoc.org/
• http://www.pbworld.com/news_events/publications/network/issue_57/57_03_murilloj_briefhistoryseg.asp
• http://www.pbworld.com/news_events/publications/network/issue_28/28_16_wahlp_constructionsequence.asp