Design Criteria for Structural Health Monitoring Systems. Application to the Construction of Arches Using the Cantilevered Cable-Stayed Technique. Tajo Bridge Experience

The design and definition of the Structural Health Monitoring Systems (SHMS) of large structures is a process of continuous updating. Its integration with domain knowledge provided by experts allows advancing in new construction procedures. The authors develop the design criteria of these SHMS and present the experience of its application in monitoring the structural response during the construction of Tajo Bridge: an arch-type viaduct with a span of 324 m, built using the cable-stayed cantilever technique. In the structural monitoring of the Tajo Bridge, a total of 114 sensors were used, which made it possible to monitor the following phenomena: (a) stress experienced by the provisional suspension tie rods; (b) existing stress in the anchors of the temporary cable-stayed towers; (c) deformation experienced by the passive reinforcement of the semi-arches and stay piers; (d) thermal gradients experienced in different sections of the semi-arches, piers and temporary stay towers; (e) acceleration experienced in different structural sections of the semi-arches and temporary suspension tie rods; (f) the rotation experienced by different sections of the semi-arches and the heads of the piers and temporary stay towers; (g) incident wind on the semi-arches, piers and temporary cable-stayed towers. The authors raise the differences techniques to control the stress in bridge stay cables: installation of load cells in active anchorages; installation of extensometers in one of the strands that make up the tie rod; and installation of accelerometers.