Noel R. Flores
(Advisor: Dr. Lauren K. Stewart)
will defend a doctoral thesis entitled,
Experimental Methods for Understanding the Performance of Impulsively
Loaded Cross‐Laminated Timber Panels
On
Friday, August 12 at 2:00 p.m.
SEB Room 122
Abstract
Cross‐laminated timber (CLT) is an innovative multi‐layered engineered wood product with
proven performance as a structural material in extreme events, including earthquake, wind,
and fire. Although research is limited, CLT has shown great potential for application in the force
protection of structures. This research bridges the gap between the quasi‐static and high strain
rate loading regimes by investigating two areas that have remained unstudied or elusive, i.e.,
rolling shear failure of CLT under impulsive, blast‐like loading and intermediate strain rates in
CLT. A novel center‐point testing system and methodology was developed that permits the
application of impulsive loading in a highly controlled and repeatable manner. The testing
system is highly adaptable and is capable of testing a variety of materials of variable widths,
lengths, and thicknesses. The impactor is interchangeable to permit changes to the load
condition. Realistic boundary conditions can be simulated empirically via changes to the
boundary condition rotational rigidity. The testing system was validated and calibrated through
a series of validation tests, finite element simulations, and via the development of a new
experimental method. The Direct Force Method (DFM) is a new experimental method for
empirically determining the force history applied to a specimen that controls for inertial effects
that arise during testing. Experiments featured multiple test phases: quasi‐static testing of
undamaged CLT specimens, impulsive testing of undamaged CLT specimens, and residual
capacity testing of damaged CLT specimens. Short span‐to‐depth ratio CLT specimens are used
throughout testing to encourage the development of shear modes of failure. As verified by the
test results, the testing system consistently produced shear modes of failure and facilitated the
observation of CLT panel behavior under impulsive loading. The testing programs validated
several hypotheses including the conditions that elicit shear modes of failure, strain‐rate
enhancement of CLT mechanical properties in the impulsive loading regime, and boundary
condition rigidity’s role in affecting change in CLT panel behavior. The conclusions made on CLT
panel behavior under impulsive loading and CLT panel residual capacity and survivability
provide validation for its implementation as a structural material in force protection
applications.
Committee
• Dr. Lauren K. Stewart – School of Civil and Environmental Engineering (Advisor)
• Dr. T. Russell Gentry – School of Architecture (Co‐Advisor)
• Dr. Laurence J. Jacobs – College of Engineering
• Dr. Lawrence F. Kahn – School of Civil and Environmental Engineering
• Dr. Karl F. Meyer – School of Civil and Environmental Engineering