A model is presented for predicting changes in the tensile, compressive, and shear strengths and moduli of timber exposed to high temperature. The strengths and moduli of southern pine exposed for predetermined lengths of time to either 100, 160, 245, 400, 600 or 800 °C were measured. The accuracy of the model was assessed by comparing the strengths and the moduli predicted by the model to the data.

A model is presented for predicting the failure time of loaded wooden beams of rectangular cross-section exposed to elevated temperatures or to fire. Failure times calculated by the model were compared to failure times measured in this study using 19.05 mm x 19.05 mm simply supported southern pine beams, and to failure times measured by the National Bureau of Standards during the fire of a full scale room. Reasonable agreements were found between the calculated failure times and the data.

Southern pine and Douglas fir test specimens were placed in an over kept at either 100, 160, 245, 400, 600, or 800 °C, and the center point temperatures and the mass losses of the specimens were measured as functions of exposure time. A model is described for calculating the temperature distribution in and the mass loss of wooden beams having rectangular cross sections. Comparisons were made between the data and the results of the model, and reasonable agreements were found between the measured and calculated temperatures and mass losses. Some tests were also performed to assess the effect of ambient oxygen concentration on the mass loss.