Case-based Decision Support for the Assessment of Bridges

• Bernhard Freudenthaler
• G. Gutenbrunner
• Reinhard Stumptner
• Josef Küng

The main idea of this contribution is computer aid for Structural Health Monitoring activities. The increasing age of infrastructure makes actions necessary to predict lifetime and to guaranty safety, especially for critical structures like bridges for example. Thereby, acceleration sensors are widely used to measure (ambient) vibrations of structures, which are stored by a connected computer system for later processing. These records are a basis for following procedures and make an assessment of a building’s condition possible. Due to several reasons, the process of analysing a signal is very complex in particular because of the individuality of each structure. This means that the measurement results (characteristics of a building) strongly depend on structure-design and a marginally different design (from layman’s point of view) can cause completely different measurement results. Consequently, only an experienced expert can interpret a measurement correctly and still, this analysis process is difficult and timeconsuming, what necessitates computer aid for the interpretation to speed it up and to improve the quality of results. This is the point where decision support in terms of Case-based Reasoning can be introduced. The idea is to transfer the expert’s experience (description of the structures’ designs and measurements incl. interpretation) into a so-called case base which is continuously growing and enhanced by future experience. The Decision Support System can, relying on these cases, compare new measurements of possibly unknown structures with measurements of known buildings (from the case base) and suggest an interpretation by means of adapting past interpretations, which were taken under similar conditions (similar structure design) using certain similarity measures.