This report deals with the fire resistance of cross-laminated timber (CLT). The main purpose is to verify a new model on CLT and its ability to sustain its bearing capacity when exposed to fire.
To establish this, a series of bending tests has been conducted in combination with fire exposure of the CLT. Two different series, with different dimensions, of beams were tested (series 1 and series 2).
Four basic set-ups: CLT in tension or compression, either equipped with fire protective covering or not. Results from the tests has been gathered and evaluated to verify the theoretical model of the fire resistance. Evaluation was made through analysis of the residual cross-sections of the beams regarding charring depth and rate and moment of inertia (I).
Results of the tests verify to a large extent the Design model. External problems and variations in the beams themselves caused some deviations.Analysis confirmed the CLT as being more similar to other laminated products such as Laminated Veneer Lumber (LVL) then homogenous solid beams.
BothCLT and LVL experience delamination when exposed to fire resulting in an increased charring rate. The difference in rate when using Gypsum plaster as a protective barrier against the fire exposure is also equal to LVL.The results of the report will be used in the new version of the European Standard, Euro Code 5 and in the third edition of Fire Safe Timber Buildings.Charring rates proved to be less than expected but the CLTs ability to with standfire while keeping its bearing capacity
Source: Jönköping University
Author: Wilinder, Per