Behaviour of Cross-Laminated Timber Subjected to Blast Loading

Abstract

Heavy timber construction is emerging as a viable alternative to conventional building materials, such as steel and concrete, for mid- and high rise structures. With the increasing presence of timber structures at or near potential targets comes an increased risk for damage to the structure and more importantly human casualties. The current provisions related to wood in the blast code (CSA, 2012) are limited and based on general understanding of the material behaviour rather than thorough research studies. Also, the standard does not clearly distinguish between the various types of engineered wood products. A study was undertaken to assess the behaviour of cross-laminated timber panels subjected to simulated blast loading using a shock tube apparatus. More specifically, the aim of this study was to investigate the behaviour of CLT panels subjected to static and dynamic loads to determine a dynamic increase factor in order to quantify high strain rate effects on this material. Testing was completed on a total of 18 CLT panels, with panel thicknesses of 105 and 175 mm corresponding to a 3-ply and 5-ply panel, respectively. An average dynamic increase factor of 1.28 on the resistance and no apparent increase in stiffness from static to dynamic loading were observed. Two resistance material predictive models that account for high strain-rate effects and the experimentally observed post-peak residual behavior were developed. A single degree-of-freedom model was validated using full-scale simulated blast load tests, and the predictions were found to match well with the experimental displacement-time histories.