Fire-Induced Damage and Postfire Analysis of the Compression Properties of Cross-Laminated Timber

Abstract

When exposed to fire, load-bearing mass timber structures, such as cross-laminated timber (CLT), soften and decompose, which causes significant deformation and weakening, ultimately leading to failure. A combined experimental and modeling analysis is presented to predict the postfire residual compression properties of CLT. Multiple experimental fire exposure and postfire mechanical tests were performed under identical conditions to respectively characterize the internal and external thermal response of the CLT and assess the residual postfire compression properties. An analytical modeling strategy based on the measured through-the-thickness temperature profile during fire exposure is presented to predict the residual postfire compression properties of the CLT. X-ray computed tomography analysis revealed the charring rate to be nonconstant, which is in line with current research findings but not in line with Eurocode design suggestions. The analytical analysis revealed the transverse (cross) lamina to provide minor contribution to the axial compression properties but critically to the thermal protection and structural integrity of longitudinal (load-aligned) laminae during fire exposure.