Development of dynamic moisture content measurement system for wooden members exposed to fire heating

Abstract

In this study, a small sensor for the dynamic measurement of the local moisture content within a wooden member exposed to fire heating is developed. The measurement is based on the unique dependence of the electrical resistance of wood on moisture content and temperature. These relationships are observed experimentally at temperatures between 20°C and 90°C, and moisture content between 6.9% and 232.8%, for Cryptomeria japonica, Larix leptolepis, Pseudotsuga menziesii, and Zelkova serrata. The electrical resistance is represented with the temperature and moisture content for each tree species. The measurement is found to be the most effective within the moisture content of 10%-30%.

Calculation Method of Collapse Time of Wood Members Exposed to Fire Heating With Heat and Water Transfer Analysis: Influence of Initial Moisture Content on Charring Rate and Mechanical Properties of Remaining Section of Wood Members

“…Moisture content is significant because an increase in moisture content caused by vapourisation, transfer, and re-condensation of water in the remaining cross-sectional area required to bear load. The experiments in [1][2][3] showed that fire heating caused an increase in the moisture content of the specimens. Such an increase decreases the mechanical properties of wood members even at room temperature.…”

Resistividad eléctrica de la madera de Pinus pseudostrobus, Tabebuia rosea y Quercus scytophylla

“…En el mismo sentido, la resistencia eléctrica se aplica para evaluar el comportamiento de la transferencia de humedad en el rendimiento de elementos estructurales de madera expuestos al fuego (Suzuki, et al, 2021).…”