A New Generation of Smart Stay Cable for the Guadiana Bridge
The Guadiana International Bridge is located 250km southeast of Lisbon on the border between Spain and Portugal. Following breakage of three strands in recent years, inspections and non-destructive testing indicated a full stay cable system replacement was needed.
Context
Erected between 1985 and 1991, the bridge has a total length of 666m and a central span of 324m. The structure also includes two 100m-high pylons. Following the breakage of two strands in recent years, non-destructive testing was conducted in 2018; a third strand broke in March 2020. Several anomalies were observed, especially in the anchorages. DYWIDAG was hired to perform a full replacement of the stay cable system.
Scope
Inspection and non-destructive testing (June – August 2018)
Replacement of stay cables (November 2019 – April 2021)
Solution
A full stay cable replacement is divided into three parts: removal of existing stay cables, interventions in existing elements, and installation of new DYWIDAG monitoring stay cables and DYWIDAG monitoring sensors.
The existing stays were individually de-tensioned and removed, followed by their deck and pylon anchorages. The stressing force for each new stay cable was defined by the force of the replaced strands, measured through a lift-off test. Once the stay cable replacement was completed, a global restressing was carried out.
The stay cable system includes a new generation of anchorages and the addition of stay pipes, magneto-inductive sensors for continuous automated cable force monitoring, and cable vibration dampers. The force monitoring system installed at the stay cables consists of elasto-magnetic force-measuring sensors, which allow a force measurement to be taken at each of the bridge’s stay cables at any time during their expected service life.
With the April 2021 completion of the recommended cable replacement and the new monitoring system, the Guadiana International Bridge is not only safe and strong, but also cutting-edge smart.
Going Further
The installation of the new stay cables started with the placement of the anchorages. It was followed by the lifting of the stay cable pipe and first strand, the installation and tensioning of remaining strands, the installation of compaction clamps and closure of the cable pipe, the post-wedging and corrosion protection of anchorages, and, finally, the installation of exterior viscous dampers. Once the stay cable replacement was completed, a global restressing was carried out.
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