Structural Fire Modeling Strategies for Exposed Mass Timber Compartments and Experimental Gaps for Model Validation

Exposed mass timber is being increasingly used for tall hybrid structures due to its sustainability features, rapid construction time, and the aesthetic desire to see exposed timber. However, there are currently many knowledge gaps in timber's performance in fire. Current prescriptive methods can be limiting, and designers are therefore required to develop alternative solutions to design tall and/or exposed timber structures. One approach that can be used to better evaluate timber's performance in fire is numerical modeling, which is often used in synergy with some form of fire testing. The authors have reviewed literature primarily published over the last 5 years to determine the state of the art of modeling timber at elevated temperatures. Following this review, an a priori model of a cross-laminated timber (CLT) ceiling subjected to a localized fire was developed in LS-DYNA to determine what data sets are currently required to better calibrate a thermal model of timber at elevated temperatures. Data sets include the flame spread rate of CLT, the heat flux produced by CLT, charring rates at high heat fluxes, and criteria for the extinction of timber.