PSI - Issue 64

Maximilian Rohrer et al. / Procedia Structural Integrity 64 (2024) 1256–1263 Rohrer, Moeller, Lenzen / Structural Integrity Procedia 00 (2019) 000 – 000 Figure 1 illustrates the principle of SP2E. The output of two systems created at different times i and j is compared in a difference process output vector . A 10-minute averaged measurement is assumed to be steady state. The same normalization input 0 , which results from the normalization model 0 , is used for both models in the SP2E method. The average power of the difference process is then evaluated as a damage indicator. 1259 4

Figure 2: Phases and EOC-vector space.

The monitoring of a mechanical system is divided into a learning phase and a monitoring phase (see Figure 2). In the learning phase, the models of the undamaged system are identified. System monitoring takes place in the monitoring phase. The models i are taken from the learning phase and form a reference state for the models j from the monitoring phase. Each model represents a linearization at a respective operating point of the mechanical system. The sensor network also records EOC such as temperature, wind speed and direction, etc. in an EOC vector p as attributes. The EOC vector p is associated with the state space model. Models i and j are assigned via the difference Δ , in the EOC vector space. This is done using k-nearest neighbor or other clustering methods. 3. Monitoring of Experimental Bridge Structure 3.1. Bridge Structure The Floßgrabenbrücke near the German town Zeitz in Saxony-Anhalt was chosen as the experimental object for SHM in Lenzen et al. (2024). It is under public administration and made available for research in SHM and monitoring. The structure spans a valley in a straight line with a total length of 358 m and is divided into seven spans. The superstructure is constructed as a trapezoidal, torsionally rigid steel composite box girder with an added in-situ concrete slab. The construction height is 2.60 m with a width of 12.00 m. Additional transverse stiffeners are welded in at 3.6 m intervals (see Figure 4).