Transient Moisture Gradient in Fire-Exposed Wood Slab

Improved fire endurance design procedures for heavy timber members may require the input of moisture content-dependent allowable stresses. Therefore, experiments were conducted to characterize the transient moisture gradient in a wood slab subjected to fire on one face. Electrodes and thermocouples embedded within the wood sections monitored moisture and temperature levels at selected locations. Time-moisture content curves indicated an increase in moisture content that appeared to be associated with the vaporization of the bound water in the wood. For the eight slabs tested, the average peak moisture content was 1.26 to 2.00 times greater than the initial moisture content.