Comparative study on fire resistance and zero strength layer thickness of CLT floor under natural fire and standard fire

Abstract

A study of the fire resistance of cross-laminated timber (CLT) flooring material exposed to different fire conditions (ISO 834 standard fire and natural fire) is described, along with the value of the zero strength layer (ZSL) thickness. Experimental studies of the flexural performance of four groups of CLT floor at ambient temperature and the fire resistance of six groups of CLT floor under the action of fire were conducted. The influence of different laminate compositions (three-ply and five-ply) and different load ratios (10%, 20%, 30%) on the internal temperature field distribution, fire resistance and carbonization of the six groups of CLT floors were compared and analyzed. Subsequently, Abaqus software was used to establish a finite element temperature field heat transfer model of the shedding of the charred layer to analyze the fire resistance of the CLT floor, and to compare the key parameters in the test (charring rate, depth of charring, and shedding of the charred layer), to verify the validity of the model. Finally, the effective residual section method was used to develop a theoretical calculation model for determining the thickness of the ZSL of the CLT floor throughout the fire process. The theoretical calculated charred depth at different times during the fire resistance tests are compared and analyzed to verify the accuracy of the theoretical method.