System Identification with Coda Waves at the Gänstorbrücke in Ulm

The Gänstorbridge in Ulm is crossing the Danube with a maximum span of 82,40 m. Among others is the bridge instrumented with 20 ultrasound transducers for structural health monitoring. These special types of ultrasound waves allow for the monitoring of concrete structures with diffuse ultrasound (coda waves). The advantages of the method include large-scale coverage of the geometry by the ultrasound and at the same time immense sensitivity to a wide range of measurable variables. These characteristics of the technology, together with the widespread use of concrete and the aim of preserving aging infrastructure for as long as possible, underline the great potential of coda waves. Instrumented is a 12 m long field in the middle of the bridge. During a closure at night, loading experiments were performed with heavy trucks that were evaluated with a focus on damage detection. To do this, an inverse problem is solved whose solution allows for the localization of damages. The focus of the article is on the presentation of the method, challenges in practical application, and the results of the load tests.