Quantitative Radiographic Investigation of Mechanical Fasteners in Wood Connections

Open Access
Author:
Adams, Andrew Ryan
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
April 10, 2009
Committee Members:
  • Bohumil Kasal, Thesis Advisor
Keywords:
  • radiography
  • beam theory
  • strain
  • dowel type fastener
  • wood connection
  • digital image processing
  • x-ray
  • edge extraction
  • differentiation of discrete data
Abstract:
This project deals with the use of digital x-ray imaging and image processing to quantitatively determine information about the strain behavior of dowels in wood connections. The developed method uses image processing techniques to extract the edge/boundary of the deflected dowel from an x-ray image, and then calculates the bending strain from the edge data using beam theory principles. This newly developed method has applications both in laboratory settings and also when investigating structures in situ after severe loading events. Feasibility and effectiveness of the method were evaluated using simplified tests consisting of dowel specimens instrumented with strain gages, so that the accuracy of the calculated strain values from digital x-ray images could be checked. The experiments provided valuable data for the development of suitable strain extraction procedures, which have been found to provide inexact but nonetheless useful information about the behavior of dowels in wood connections. Overall, the method presented here forms a useful tool which can be used by researchers and engineers, and also establishes a solid, verified starting point for the development of more sophisticated and accurate methodologies to calculate strains from deflected edge data found by digital image processing.