CREEP MODELING OF WOOD USING TIME-TEMPERATURE SUPERPOSITION

The time-temperature superposition principle was used to develop long- term compression creep and recovery models for southern pine exposed t o constant environmental conditions using shortterm data. Creep (17-ho ur) and recovery (40-hour) data were obtained at constant temperature levels ranging from 70 F to 150 F and constant equilibrium moisture co ntent (EMC) of 9%. The data were plotted against log-time, and the res ultant curve segments were shifted along the log-time axis with respec t to the curve for ambient conditions to construct a master curve appl icable to ambient conditions (70 F, 9% EMC) and a longer time period. The master curves were represented by power functions, and they predic ted up to 6.4 years of creep and 5.8 years of recovery response. The v alidity of the master curves for predicting creep of wood exposed to t he normal interior environment in buildings was tested by conducting t en-month creep tests in the laboratory. The fluctuating environment ca used geometry changes in the surface of the specimens affecting the co llected long-term data. Therefore, a good comparison between the maste r curves and the long-term data was not possible.