Dimensions - Fall 2013 - 8

vision: innovation
Florida's first anchored end-span bridge is
that perfect blend of form and function that
the Orlando-Orange County Expressway
Authority was looking for.

Integrating Roadway
Superstructures into
Surrounding Environments
A Focus on Function, Reliability, and Aesthetics
As communities continue to expand and once rural areas

An innovative and rare bridge design that had

are connected by a vast number of roadways, structural

gained some traction in the Midwest, the anchored

aesthetics are becoming as important as reliability and

end-span bridge in Orlando is a three-span structure

functionality. Bridges and other superstructures in

with variable-depth steel plate girders of 71-feet, 286-feet,

particular offer the greatest opportunity for enhanced

and 71-feet. The bridge's intermediate bents are supported

aesthetics due to their obvious visibility and geometrical

by a substructure made up of multi-column piers, while

potential. Occasionally, this forces the designer to

a full-height concrete cantilever abutment supports the

experiment with new combinations of structural

end bents. The short end-spans and intermediate piers

components to create the perfect fit of form and function.

are bound by textured precast concrete walls that match

The Orlando-Orange County Expressway Authority

the approaching 45-foot retaining walls. Since the driven

(OOCEA) had just such a request: design an aesthetically

concrete pile foundations could not be in tension, the

pleasing bridge with a clear span of 286-feet for a high

design called for appropriately sized abutment footings that

visibility interchange location. OOCEA had just finished

offset the superstructure uplift forces with the dead load.

constructing a nearby bridge of similar length, and after

The cast-in-place concrete deck is supported by

seeing the finished product, placed a higher emphasis on

haunched steel plate I-girders that vary in height from

the aesthetics of the new bridge. Such a long single-span

nine feet at the supports to just six feet at the center. Such

bridge would typically require a very deep beam, but

a gentle taper is the aesthetic touch that allows the bridge

this would not address the client's emphasis on form

to integrate into the surrounding residential area. The

and function. Bowyer-Singleton, now Dewberry |

final bridge appearance is slender and imitates the look of

Bowyer-Singleton's (see page 9) solution was instead to

a single-span bridge.

design a structure with "anchored" end spans to offset the
significant uplift forces of the unbalanced spans.

8

Dimensions

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http://www.dewberry.com/news/blog/13-08-22/An_Innovative_Idea_for_a_Challenging_Location
Dimensions - Fall 2013

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