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Uplift upgrade
State-of-the-art uplift bearings have now been installed to replace the antiquated pin-and-link devices that originally secured the superstructures of the Delaware Memorial Bridge.
The Delaware Memorial Bridge in the United States, twin suspension bridges connecting the states of Delaware and New Jersey across the Delaware River, were constructed with a pair of upright pinned links supporting the end of each superstructure at each tower. After over fifty years of service it was decided to replace this support system at all 16 locations, implementing a modern structural bearing solution instead. This significant change to the bridges’ superstructure support concept presented a number of challenges for the structural bearing design and supply, including large movements and rotations, load reversals with high uplift forces, and high long-term accumulated movements. The bearings were also required to temporarily (but not permanently) resist transverse forces, and to be designed for integration in the bridge’s monitoring system, with sensors to measure loads, displacements, rotations and loss of sliding material thickness due to wear.
Fortunately, mageba already had very useful experience in supplying a solution for a very similar project just two years earlier, at the Forth Road Bridge in Scotland. Applying that experience to meet the project’s requirements, mageba proposed a solution based on the tried-and-trusted RESTON® SPHERICAL bearing, with pre-integrated sensors for connection to the bridge’s structural health monitoring (SHM) system. Details of the requirements are provided on mageba’s project reference sheet, and the bearings’ design is illustrated by the attached images.
With the bridge bearings having now all been installed, the Delaware Memorial Bridge’s superstructures are optimally supported at each end using modern technology. The equipping of the structural bearings with sensors of various types for integration in the bridge’s SHM system, enabling online presentation of recorded data and immediate notification of unexpectedly high or low values of any variable, will also contribute to the maintenance and long-term proper performance of the bridge bearings in the structure, and to a degree, of the bridge as a whole. With these high-spec bearings installed to replace support mechanisms of a very different type, the project demonstrates how exceptional engineering structures, and extraordinary bridges in particular, often require unique, innovative solutions – solutions which can only be provided by suitably experienced suppliers.
“Frequent uplift (tension-compression) loads require a well thought detailed design given the high risks & costs associated with repair / replacement of uplift bearings. We are proud to have collaborated with HNTB and the DRBA in developing a custom solution and supply first of its kind uplift spherical bearings in the USA, equipped with a monitoring system. Fabrication in Asia, thorough load testing in Europe, and final installation by the American Bridge Company in the USA ended up being a truly global collaboration in successful execution of this challenging project.”
Amit Kutumbale, Technical Manager – Bearings, mageba USA
Owner: Delaware River and Bay Authority
Contractor: American Bridge Company
Engineer: HNTB Corporation
