This paper focuses on evaluating the effectiveness of an unmanned aerial vehicle (UAV) as a supplementary bridge damage quantification tool. For this study, a glued-laminated timber arch bridge in South Dakota was selected, and an UAV was utilized for the bridge damage quantification. A recommended four-stage UAV-enabled bridge damage quantification protocol involving image quality assessment and image-based damage quantification was developed. A field application using the UAV to measure crack lengths, thicknesses, and rust stain areas of the selected bridge was conducted following the recommended protocol. The image quality parameters, including sharpness and entropy, were used to determine the quality of the UAV-captured images. Pixel- and photogrammetry-based measurements using the high-quality images were obtained to quantify the bridge damage, and the damage was compared to that from actual field measurements. Once the damage information was gathered, the UAV image–based damage level classification was established based on the damage levels defined by current standards. The findings confirmed the accuracy of the recommended protocol, with results within 3.5, 7.9, and 14.9% difference for crack length, thickness, and rust stain area, respectively, when compared with the field measurements.
The development of wide-span structures occurs high reaction forces at the bearings. The load-bearing capacity is strongly limited, because of the low compression strength and stiffness of wood perpendicular to the grain. One common possibility of strengthening the support is the application of self-tapping screws ,. Subject of the presented research project is the study of a new, practicable and quite easy to manage type of reinforcement for load transfer areas. To increase the load carrying capacity drill holes and block shaped areas filled with polymer concrete are inserted into the timber. Due to the rigid bond between wood and polymer concrete as well as a geometrical adaption to the stress distribution, it is possible to increase the load carrying capacity and the compressive stiffness significantly compared to conventional reinforcement by self-tapping screws.
First inchoate versions of bearing reinforcement have been designed and used very successfully as part of another research project to increase the bending capacity of glulam beams by hybrid material composites ,. Figure 1 shows one example of the tested designs. The diagram in Figure 2 illustrates the increase of the transversal load bearing capacity compared to FE-simulation of the same member without reinforcement.