Continuing Education

Using Photogrammetry-Based Imperfection Measurement Tools to Determine the Impact of Corner Radii Imperfection on Cold-Formed Steel Member Strength

Despite recent advances in imperfection measurement tools, accurate corner radius measurements have remained elusive. While imperfect corner radii can impact section properties. The objectives of this research project are to (i) quantify the impact of imperfect corner radii on cold- formed steel member strength, (ii) provide a tool to determine cross-section imperfections via photogrammetrybased image processing. Lipped channel sections with imperfect corner radii are analyzed using the finite strip method and their stability characteristics are compared to those of the corresponding perfect sections. Analyses presented herein demonstrate that any increase in corner radii can have an impact on the strength of the sections. Additionally, the work examines the role of section geometry and aspect ratio in the observed differences. Various sections are studied to examine the impacts of web-flange aspect ratio and proportion comprised of corner radius. The second component of the work introduces a low-cost, open access, and easily-distributed imperfection measurement tool utilizing photogrammetry. With this new tool, users are able to capture accurate cross-section measurements (including corner radius) with a standard cell phone camera and directly input the measurements into finite strip method analysis. Several examples are done in a lab by a cell phone camera and nominal dimension of sections are compared to their accurate one.
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  • Date: 4/10/2018 - 4/13/2018
  • PDH Credits: 0


Abbas Joorabchian and Kara D. Peterman; University of Massachusetts Amherst; Amherst, MA

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