Experimental study of the charring rate of tropical hardwoods

摘要

This paper describes an experimental investigation of the charring rates of timber. An experimental procedure was designed for assessing the charring rate of 20 specimens exposed to fire in a single test, with one-dimensional heat transfer conditions. Each test specimen was manufactured by gluing seven laminates together. Four thermocouples were inserted at different depths in four different laminates located in the middle of the test specimen. The test was conducted using a gas-fired furnace and specimens were exposed to the standard ISO 834 fire. In order to evaluate the fire performance of tropical hardwoods, seven different species with densities ranging from 500 to 1000 kg/m~3 were used. For the purpose of verifying the experimental procedure against existing data, two softwood species (spruce and fir) and one European hardwood species (oak) were also examined. Experimental results indicate that the test method and procedure can be used for assessing the charring rate of timber both for softwood and for hardwood species. They also show that the density of wood significantly affects the charring rate and that the values recommended in Eurocode 5 for high densities are somewhat too conservative.