Influence of moisture content on the structural properties of wood under high temperature: - Exposure moisture content dependence of Young's modulus and bending strength under heating of Cryptomeria Japonica and Zelkova serrata

The structural properties of Cryptomeria Japonica, a softwood commonly used in timber engineering, and Zelkova serrata, a hardwood normally used in traditional large buildings, heated up to 95°C were measured at the elevated moisture content and temperatures as an engineering basis for the structural fire safety design of large-scale timber buildings. The results show that the Young's modulus of two species at the elevated moisture content and temperatures was largely affected by the moisture content over 10% and the heating temperatures 80°C or higher. The bending strength at normal temperature or higher was highly dependent on the moisture content, however two species showed different declining trends with the rise of moisture content and temperatures. The correlation between Young's modulus and bending strength of Cryptomeria Japonica keep to the same with the rise of the moisture content and temperatures. On the other hand, the correlation of Zelkova serrate became weaker with the rise of temperatures.