Non‐linear simulation of Cross‐Laminated Timber (CLT) delamination under fire conditions using FEM numerical model

Abstract

Cross-laminated timber (CLT) is an engineered timber product manufactured with an odd number of timber layers placed crosswise to each other. These structural elements are widely used in the construction field. Although the behaviour of CLT under fire conditions is known, there are challenges of knowledge that require more in-depth research, such as flame spread, thermal degradation, self-extinction, and delamination during heating. This work focuses its research on the simulation of delamination during heating. Numerical simulation using finite element methods (FEM) is widely used to predict and simulate the thermal behaviour of CLT elements under heating conditions. The objective of this study is to develop a numerical model using FEM to simulate the delamination of CLT under fire conditions using existing data from the literature. Delamination occurs when one layer falls off the main mass of timber. Under fire conditions this is due to an alteration of the cohesive properties of the adhesive between the layers. In order to simulate delamination, the Birth and Death element can be used to deactivate contact elements between layers in a thermal analysis, reducing the section and modifying the properties of the interface layer. The thermal properties of timber, such as thermal conductivity, density and specific heat are a function of temperature. The results of this work show that the developed model can predict temperature profiles and char formation, as well as delamination during the heating process. This work combines advanced numerical techniques to simulate delamination of CLT under fire conditions. As a future work, the FE model should be calibrated and validated by comparing the results with experimentally measured data.