Long Span Bridges & Vibrations
Full Session with Abstracts
343155-2 - Margaret Hunt Hill (MHH) Bridge
Saturday, April 21
8:00 AM - 9:30 AM
The City of Dallas envisioned an iconic bridge that would artfully grace the Dallas skyline while inspiring connectivity between north and south sectors of Dallas. The City also wanted to encourage economic growth around downtown Dallas and provide continuity with the urban Trinity River park. With these objectives in mind, the City retained Santiago Calatrava for his renowned artistic, architectural and engineering talents.
The principle signature features of the MHH bridge are the center arch pylon soaring to a height of 440 feet above the floodplain, coupled with the unique stay cable arrangement. The steel arch pylon is formed by two inclined tower legs that join at the top and form a parabolic curve. The circular pylon section has a 15’-1” base diameter and uniformly tapers to a 12’-0” apex diameter. There are 58 individual stay cables uniformly spaced around the top of the arch pylon and connected along the superstructure’s central box girder centerline below. The stay cables vary in length from 390 to 642 feet.
The unique superstructure cross section consists of a steel central (spine) box girder with tapering cantilevered steel transverse floorbeams spaced every 20 feet. The 14-foot wide by 12-foot deep central box girder, supported by the arch stay cables, provides the necessary torsional stiffness and bending capacity to the structural system. Longitudinal steel stringers span between the floorbeams and support the cast-in-place concrete deck. The superstructure skeleton provides a spectacular graceful image, especially for the park patrons within the floodplain below.
Unique structures, like the MHH bridge, require engineering experience and good judgement to compliment the design codes and guidelines prepared for more traditional bridges. As an example, a comprehensive wind tunnel study was preformed to supplement current design guidelines while fully evaluating the structural system behavior for a variety of wind loading conditions.
This presentation is targeted to a national audience of bridge design professionals.