In case of induced seismicity, expectations from a structural monitoring system are different than in the case of natural seismicity. In this paper, monitoring results of a historical building in Groningen (Netherlands) in case of induced seismicity has been presented. Results of the monitoring, particularities of the monitoring in case of induced earthquakes, as well as the usefulness and need of various monitoring systems for similar cases are discussed. Weak soil properties dominate the structural response in the region; thus, the ground water monitoring as well as the interaction of soil movements with the structural response has also been scrutinized. The proposed study could be effectively used to monitor historical structures subjected to induced seismicity and provide useful information to asset owners to classify the structural health condition of structures in their care.It was shown that the in-plane cracks at the building would normally not be expected in this structure during small induced earthquakes happening in Groningen. One explanation provided here is that the soil parameters, such as shrinking of water-sensitive soil layers, in combination with small earthquakes, may cause settlements. The soil effects may superimpose with the earthquake effects eventually causing small cracks and damage.
DOCUMENT
Post-earthquake structural damage shows that wall collapse is one of the most common failure mechanisms in unreinforced masonry buildings. It is expected to be a critical issue also in Groningen, located in the northern part of the Netherlands, where human-induced seismicity has become an uprising problem in recent years. The majority of the existing buildings in that area are composed of unreinforced masonry; they were not designed to withstand earthquakes since the area has never been affected by tectonic earthquakes. They are characterised by vulnerable structural elements such as slender walls, large openings and cavity walls. Hence, the assessment of unreinforced masonry buildings in the Groningen province has become of high relevance. The abovementioned issue motivates engineering companies in the region to research seismic assessments of the existing structures. One of the biggest challenges is to be able to monitor structures during events in order to provide a quick post-earthquake assessment hence to obtain progressive damage on structures. The research published in the literature shows that crack detection can be a very powerful tool as an assessment technique. In order to ensure an adequate measurement, state-of-art technologies can be used for crack detection, such as special sensors or deep learning techniques for pixel-level crack segmentation on masonry surfaces. In this project, a new experiment will be run on an in-plane test setup to systematically propagate cracks to be able to detect cracks by new crack detection tools, namely digital crack sensor and vision-based crack detection.
