Use of Photogrammetry to Assess the Condition of Structural Concrete

Sabrina Ballard

Abstract


According to the American Society of Civil Engineers (ASCE) 2013 report card, the Nation has a grade of a D+ in infrastructure. This is because civil infrastructure in the United States is reaching the end of its expected service life. Demolishing and replacing infrastructure is unsustainable both from an economic and environmental standpoint. There is a need for new methods in verifying the remaining life of the engineered environment, and photogrammetry (the science of making measurements from photographs) will satisfy this need. The purpose of this study is to validate the use of photogrammetry for determining strains and crack widths. This will be accomplished by loading a 150 mm x 150 mm x 460 mm concrete block and comparing strain measurements calculated from photogrammetry to those of strain gauges or extensometers. This project also compares crack width measurements from high-resolution orthorectified photographs to those obtained using a crack comparator card or microscope. This research is unique due to the scale of the project, and because strain measurements rather than deflections are being analyzed. Upon conclusion, it is anticipated that traditional measurement techniques (strain gauges, extensometers, crack comparator card, and microscope) will yield similar results to those obtained from photogrammetry. The implication of these results is that professional engineers can adopt photogrammetry methods to assess the condition of existing structures. With a large amount of infrastructure failing and in need of repairs, this research will benefit the engineering community because it is a robust and quantitative means of assessing the condition of the Nation’s infrastructure.


Keywords


Photogrammetry; Concrete; Strain Measurement; Crack Width

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