Design methodology for cross-life structural health monitoring with unknown damage process

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Traditional structural health monitoring is usually used a) to monitor known deterioration processes and their temporal development in older existing structures or b) to check the assumptions made in the design of new structures with a high degree of innovation. In these applications, however, the monitoring period is limited to between a few months and a few years, and the physical parameters to be monitored and their effect locations are clearly defined. In the future, long-term electronic monitoring will become an important tool for the maintenance of infrastructure buildings, which is associated with the following new challenges: - significantly longer monitoring period (several decades up to the entire service life of the structure) and - initially unknown damage mechanism, time of occurrence and location. The objective of this sub-project is to develop a design methodology that can be used to reliably design a monitoring system for this new application area. The development process can be divided into two parts: one is related to the building and the other one is related to the measuring system. The interface is the definition of the physical parameters to be measured. The focus of this project is on the building-related area in phase 1 of the Priority Programme. The methodology to be developed shall be limited first to the application to prestressed concrete bridge structures, even though the basic methodology is transferable to other types of structures. The scientific challenge of the research project is based on the fact that presently available measurement methods can only monitor limited areas with sufficient resolution. Since monitoring is to begin at the start of the structure's service life, no damage processes have yet been initiated on the object. Complete sensor-based monitoring would, therefore, require a dense sensor network over the entire structure, which would be neither economically nor technically feasible. The scientific knowledge benefit of the sub-project is, therefore, how a reliable measurement concept can be designed with initially unknown damage mechanism, time of occurrence and location. The main question is which physical parameters with which resolution (local, temporal, measurement range) shall be recorded on a specific structure. To answer this question, two interacting approaches are applied: a cluster-related and an object-related approach. The cluster-related approach is based on the systematic evaluation of existing similar structures. For this purpose, a comparison group with similar characteristics is formed for the specific object. The object-related approach is based on a dedicated analysis of the specific building. For this purpose, the typical evaluation methods for existing structures are placed in the context of future measurement technologies. Both approaches are to be integrated into the methodology to be developed and tested on the Weserstrom bridge in the course of BAB A2.