Bridge Analysis, Design and Repair
337813 - Dallas Horseshoe Project - Spliced Concrete Girder Design and Construction Overview
Friday, April 20
3:30 PM - 5:00 PM
In early 2013, design work began on the Dallas Horseshoe, an $800 million highway improvement project intended to replace critical but obsolete IH-30 and IH-35E Trinity River bridges, and to generally improve traffic through the downtown Dallas “mixmaster”. The project earned its name from its U-shaped overall layout, with IH-30 forming one leg, and IH-35E the other, and serves some 450,000 to 500,000 vehicles each day. In April 2017, the project achieved substantial completion.
Six long-span continuous concrete post-tensioned spliced girder bridges cross the river, each with multiple spans of least 250 feet, forming units of 1000 feet or more. These bridges span a long-planned, but as-yet unrealized chain of recreational lakes within the river levees, as well as a controversial planned toll road, and many bike and pedestrian trails.
Being only the third application of spliced concrete girders in North Texas, the design and construction team faced many challenges. This paper will discuss:
1) Design – iterative, step-wise analysis, time-dependent considerations, composite action, shoring assumptions and cumulative stress tracking, multiple stages of prestress, limit states, serviceability, and detailing,
2) Segment prefabrication, use of self-consolidating concrete, and initial prestressing,
3) Temporary shoring design, coordination, and installation,
4) Transportation, handling, erection, control of alignment, and camber,
5) Tendon installation, decking, stressing, and tendon duct grouting,
6) Construction challenges – broken tendons, duct grouting, shoring issues, and field modifications.
TxDOT solicited design-build delivery proposals for the project in 2012, due to the complexity, scope, and context of the project, and awarded a contract to Pegasus Link Constructors, LLC (PLC), a joint venture between Fluor Enterprises, Inc. and Balfour Beatty Infrastructure, Inc. PLC teamed with WSP, serving as lead designer, partnered with AECOM. Other improvements included numerous conventional bridges, several retaining walls, and some 73 lane-miles of new roadway – along with construction of two “signature” steel arch bridges, designed by Santiago Calatrava, with Huitt-Zollars serving as EOR.
The WSP and AECOM design team will survey the unique aspects of building with spliced concrete girders, and differentiate them from conventional, simple-span girders in common use in Texas.