Image-Based Deformation Monitoring of Statically and Dynamically Loaded Beams

Abstract

(i.detchev, ahabib, melbadry)@ucalgary.ca Commission I, WG I/3 KEY WORDS: close range, digital, photogrammetry, camera, image, acquisition, three-dimensional, precision, reconstruction ABSTRACT:Structural health monitoring of civil infrastructure systems is an important procedure in terms of both safety and serviceability. Traditionally, large structures have been monitored using surveying techniques, while fine-scale monitoring of structural components has been done with instrumentation for civil engineering purposes. As a remote sensing technique, photogrammetry does not need any contact with the object being monitored, and this can be a great advantage when it comes to the deformation monitoring of inaccessible structures. The paper shows a low-cost setup of multiple off-the-shelf digital cameras and projectors used for threedimensional photogrammetric reconstruction for the purpose of deformation monitoring of structural elements. This photogrammetric system setup was used in an experiment, where a concrete beam was being deformed by a hydraulic actuator. Both static and dynamic loading conditions were tested. The system did not require any physical targets other than to establish the relative orientation between the involved cameras. The experiment proved that it was possible to detect sub-millimetre level deflections given the used equipment and the geometry of the setup.

Structural Dynamic Deflection Measurement With Range Cameras

“…Four measurement systems were used: a range camera system comprising three SR4000 devices; an eight‐camera and a two‐projector digital photogrammetric system (Detchev et al., , ); a single Microsoft (MS) Kinect sensor; and five Keyence LK‐G407 CCD LDSs (Keyence, ). The three optical sensor systems were rigidly mounted to a rigid steel scaffold frame approximately 1·9 m above the top of the concrete beam with a nadir‐looking orientation.…”

“…Over 36 000 load cycles were applied from 24 to 96 kN causing 4 mm displacement amplitude QI et al Structural dynamic deflection measurement with range cameras (8 mm peak-to-peak displacement) at the beam's mid-span in Experiment I, and from 24 to 72 kN producing 2Á6 mm displacement amplitude at the mid-span in Experiment II. In both experiments the fatigue loading cycles were applied at two different frequencies: 1 Hz to match the sampling frequency capability of the low-cost digital camera system (Detchev et al, 2012; and 3 Hz, which simulates the common traffic load frequency on bridges (Papakonstantinou et al, 2001;Heffernan and Erki, 2004).…”

“…Detchev et al. (; ) report a photogrammetric system comprising multiple off‐the‐shelf digital cameras and projectors for both static and dynamic load test measurement. However, the cameras' low frame acquisition rate limits the loading frequency that can be measured to 1 Hz, whereas 3 Hz is normally required (Papakonstantinou et al., ; Heffernan and Erki, ).…”

“…Optical techniques based on digital photogrammetry (Fraser and Riedel, 2000;Whiteman et al, 2002;Maas and Hampel, 2006;Barazzetti and Scaioni, 2010;Ye et al, 2011;Kwak et al, 2013) and terrestrial laser scanning (Gordon and Lichti, 2007;Park et al, 2007;R€ onnholm et al, 2009) have been shown to be very effective and accurate (millimetre level or better) for static load test measurements. Detchev et al (2012;2013) report a photogrammetric system comprising multiple off-the-shelf digital cameras and projectors for both static and dynamic load test measurement. However, the cameras' low frame acquisition rate limits the loading frequency that can be measured to 1 Hz, whereas 3 Hz is normally required (Papakonstantinou et al, 2001;Heffernan and Erki, 2004).…”

Developing an Optical Image-Based Method for Bridge Deformation Measurement Considering Camera Motion

“…Non-contact-based measurement approaches use high technology instruments in order to overcome the drawbacks of the conventional deformation sensors. Laser Doppler Vibrometer (LDV) [ 5 , 6 ], Global Positioning System (GPS) [ 7 , 8 , 9 , 10 , 11 , 12 ], laser scanning [ 13 , 14 , 15 ], and image-based measurement methods [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ] are among the most popular non-contact devices. However, all of these methods suffer from drawbacks that limit their application for deformation measurement of bridges.…”