ABSTRACT
At present, the inspection of the beam bottom apparent diseases mainly depends on the visual inspection and special inspection carried by the inspection vehicle. Such methods cannot form a standardized and digital data management of the apparent diseases, also it cannot guarantee the personal safety of the inspectors. The imaging principle of optical camera was introduced and a standardized imaging strategy for beam bottom scanning based on optical camera was proposed in this paper. The strategy has been verified on the bridge and can meet the requirements of concrete apparent disease detection in the specification. The results show that two standardized imaging modes, physical fixed focus and dynamic zoom, were proposed. According to the two imaging modes, the relationship between camera operating parameters was analyzed. The standardized imaging mode provides the calculation basis for the design and selection of the beam bottom apparent disease detection equipment. Based on the idea of grid division of beam bottom area, two basic scanning strategies in longitudinal and transverse directions were proposed. The transverse scanning method was recommended for the surface inspection of the bottom of the variable cross-section continuous box girder bridge. The apparent disease detection and imaging technology based on machine vision can facilitate the management of process parameters and the preservation of results, also it can provide reference for the rapid detection of apparent diseases at the bottom of other bridges of the same types.
