Fiona O’Donnell is a PhD candidate in the Structural Engineering and Mechanics program at the University of Massachusetts Amherst. She is currently spending the summer as a visiting PhD student at the Institute for Sustainable Construction at Napier University.
Fiona’s research investigates the influence of knots on the structural properties of cross laminated timber comprised of traditionally underutilized species through computational modeling and experimental testing. Cross Laminated Timber (CLT) is a massive wood composite panel employed in large scale construction floor, wall, and roof assemblies as a cost effective and environmentally friendly alternative to traditional building materials. Currently, CLT is fabricated from high quality species which is defined, in part, by limitations on the knot size since knot defects have a significant influence on structural performance and effective material properties. However, CLT has a composite nature that is inherently forgiving of defects. Investigating the feasibility and potential of using traditionally low-value woods in CLT will give rise to more sustainable building practices and increased job opportunities in rural areas. A series of analysis methods have been created and are employed to determine the structural viability of low-value species in CLT panels: stochastic geometric characterization of knot defects, a finite element multi-scale analysis of knots, experimental evaluation of low-value species material properties, and an investigation into other strength reducing naturally occurring defects.