Cross Validation of the Final Design for the Margaret Hunt Hill Bridge
The Margaret Hunt Hill Bridge is a cable stayed bridge with a main span of 365.0 m and with a 122.0 m tall main central arch. The bridge was designed by the world famed architect Santiago Calatrava, and it is part of the City of Dallas’s Trinity River Corridor Project. The bridge represents an example of a cable stayed mixed steel-concrete structure, where the stay cables are asymmetrically connected to the center of the deck and to the top of the central transverse steel arch. The steel subcontractor for the construction of this bridge is Cimolai Spa of Italy, who selected EnginSoft to perform a thorough investigation of the ultimate, service and extreme behavior as a cross validation of its final design, before construction.
The Role of EnginSoft
As part of the investigation of the ultimate, service and extreme behavior as a cross validation of its final design, before construction, the following aspects were covered by the EnginSoft study:
- the cable tensioning sequence is investigated to produce a symmetric pre-camber configuration for the main arch
- load combinations are evaluated according to AASHTO LRFD Bridge Design Specifications
- cable loss and replacement scenarios are studied according to the PTI document “Recommendations for Stay Cable Design, Testing and Installation”
- a detailed plate and beam finite element model needed to be built to provide an accurate insight on the global bridge behavior as well as the main structural details (i.e. cable connections with central steel box girder and on the main arch, support conditions for lateral cantilever on the main arch, etc.)
The complete analysis of the bridge, including construction sequence (allowing for short/long term concrete behavior and creep effects, shrinkage etc.) needed to be performed in a very limited time frame. The safety impact of modifications to the original design needed to simplify the constructability of the bridge had to be quickly assessed. Additional information needed to be obtained from a detail analysis of the main structural components such as weld throat sizes, fatigue-prone locations and stress concentrations. EnginSoft provided a number of in-house routines to efficiently perform the above task complying with the time constraint.