Reduction of the dynamic modulus of wood due to exposure to the fire. Evaluation by stress waves

Abstract

Wood is a combustible material. Therefore, architectural design and engineering calculation require experimental information on parameters for the manufacture of products and/or wood structures. The objective of the research was to measure the decrease of the dynamic modulus of the wood, caused by the exposure to the fire of pieces with small dimensions. Wood specimens of Tabebuia rosea, Andira inermis, Juglans pyriformis, Quercus spp. and Cordia elaeagnoides were studied. The apparent density, the wave velocity, the dynamic modulus and the mass decrease were determined. After the fire reaction tests, in the five species it is observed that the loss of mass is inverse to the apparent density of the wood. The wave velocity does not vary significantly before and after the treatment. However, the dynamic modulus decreases proportionally to the loss of mass. The results show general trends for the set of all the specimens of the five species studied. However, the magnitudes resulting from the measurements are particular for each species.