School of Civil and Environmental Engineering
Ph.D. Thesis Defense Announcement
Investigating the ballistic performance of cross-laminated timber (CLT) and enhanced timber composites for military construction
By Juliet Swinea
Advisor:
Dr. Lauren Stewart (CEE)
Committee Members:  Dr. Russell Gentry (CEE), Dr. Peter Stynoski (US Army ERDC), Dr. Naresh Thadhani (MSE), Dr. Iris Tien (CEE)
Date and Time:  April, 8, 2025.  2:00pm-3:00pm
Location: 1116 East Seminar Room Klaus
Teams link
Complete announcement, with abstract, is attached.

Permanent and temporary military structures must meet force protection design requirements, namely resistance to blast explosion, ballistic impact, and forced entry. Historically, the United States’ Military has used carbon intensive and single use building materials (e.g. concrete and steel) to resist operational threats because current, lightweight, modular light frame wood or metal gauge structures, although advantageous from a deployability standpoint, do not meet protective requirements. To satisfy both protective and constructability needs, a new sustainable, renewable, and domestic alternative building material, cross-laminated timber (CLT) has gained popularity due to its ease of assembly, aesthetic appeal, and strength-to-weight ratio. CLT is advantageous in a deployed environment due to quick construction modularity, but also, as a layered composite material, allows other non-wood ballistic resistant materials to be introduced into the layup and drive down thickness requirements to resist threats. The overarching theme of this work is to aid the safe and informed integration of CLT and multi-material layered timber composites into protective design through ballistic experimentation of different wood species, layup processes, and treatment mechanisms. With experimental results and post-testing nondestructive imaging, we were able to evaluate multi-material interface mechanics, and with the past and current CLT ballistic database, predict ballistic performance of CLT and layered multi-material timber composites with an additive predictive framework using a combination of physics based and probabilistic reliability methods. The work presented in this dissertation furthers the broad use of CLT structural systems in protective structural design, both domestically and internationally.