Image-based monitoring of civil engineering structures

Today, many large-scale civil engineering structures are permanently monitored to provide early warnings and to initiate counter actions from structural failure. This monitoring is commonly referred to as Structural Health Monitoring (SHM). Currently used measurement equipment for SHM involves accelerometers for vibration monitoring and total stations or Global Navigation Satellite System (GNSS) instruments for displacement monitoring. The drawback of the currently used equipment is that access to the monitored structure is required to attach the measurement sensors (accelerometers or GNSS antennas) or special geodetic prisms (for total station measurements). Furthermore, different types of instrumentation are needed to measure vibrations and displacements. We therefore investigate the usage of an Image Assisted Total Station (IATS) for vibration and displacement monitoring. The Augarten footbridge in Graz, Austria is used as test-bed to compare the IATS measurements to the conventional measurement equipment (total station and accelerometer). It was demonstrated that the IATS can identify the dominant frequencies in the structure's oscillation and can detect displacements at sub-millimeter level. By using prominent features of the observed structure as natural targets, the IATS measurements have the advantage that access to the monitored structure is not required. Watch a demonstration video below or download the video directly!
Related publications

Ehrhart M., Kalenjuk S., Lienhart W. (2017) Monitoring of bridge vibrations with image-assisted total stations. Proc. SMAR 2017. PDF

Ehrhart M., Lienhart W. (2015) Monitoring of civil engineering structures using a state-of-the-art image assisted total station. Journal of Applied Geodesy 9(3): 174–182. DOI

Ehrhart M., Lienhart W. (2015) Development and evaluation of a long range image-based monitoring system for civil engineering structures. Proc. SPIE 9437. DOI PDF

Ehrhart M., Lienhart W. (2015) Image-based dynamic deformation monitoring of civil engineering structures from long ranges. Proc. SPIE 9405. DOI PDF

Ehrhart, M., Lienhart, W. (2016) Accurate Measurements with Image-Assisted Total Stations and Their Prerequisites. J. Surv. Eng.  143(2): 04016024, 10.1061/(ASCE)SU.1943-5428.0000208