Tornado Hazard Assessment of Residential Structures Built Using Cross-Laminated Timber and Light-Frame Wood Construction in the US

Research has continued to broaden understanding of tornadoes and their effect on civil infrastructure. Because a significant portion of the losses associated with tornado events impact residential structures, it is appropriate to conduct a risk-based hazard assessment of these structures, particularly those constructed using wood because more than 90% of residential buildings are constructed of wood. In addition, alternatives to light-frame construction, including cross-laminated timber (CLT), provide stronger and more resilient structures. CLT is an engineered wood product made of gluing orthogonal layers of dimensioned lumber to produce panels. In this study, the performance of traditional light-frame construction and CLT archetypes was used to calculate the risk associated with tornadoes. In addition, a tornado hazard database was used to determine the geographic variation in risk associated with residential structures built using CLT and light-frame construction. This risk was quantified in terms of the annual probability of failure, reliability index, and the expected average annual loss. Comparisons of annual probability of failure and reliability index show that, for large portions of the United States, light-frame construction following the current practice exhibits a relatively low reliability. In those same areas, CLT structures designed in accordance with the current code standards and engineering principles exhibited a significantly smaller annual probabilities of failure and larger reliability index. A comparison of cost (direct building and content losses) showed that tornado hazards alone do not make it economically advantageous to build using CLT; however, consideration of additional hazards (e.g., nontornadic wind and earthquake) and other indirect losses (e.g., interruption cost and loss of lives) could make it an alternative worth considering.