Abstract:

The displaced and partially-decayed larch and pine timber frames from the Hall of Military Prowess, the Palace Museum, were collected and visually classified into five categories of decaying. After measuring the radial and tangential penetrations with Pilodyn, the classified wood samples were determined for wood densities and the relationships between Pilodyn values and wood densities were analyzed from measurements of 125 larch samples and 60 pine samples. The regression models of wood density as function of Pilodyn values were used for assessing the feasibility of quantitative analysis of wood quality in ancient architectures. The results showed that wood density decreased and the Pilodyn values increased with degree of decaying and there existed significant differences in wood density and the Pilodyn values among the decay classes. The wood density variation and the Pilodyn values variation of radial and tangential penetrations with decaying were highly consistent between the two wood types. For the wood samples of decaying category 4, their densities decreased 20%, and radial and tangential penetrations increased 110%～136%, compared with non-decayed wood samples. There were significant linear correlations between the tangential and radial penetrations of Pilodyn, and significant power function relationship between wood density and tangential penetration, and between wood density and radial penetration for both wood types (P<0.01), the values of correlation coefficient, r, were -0.67 for larch and -0.76 for pine for the relationship between wood density and Pilodyn values of tangential penetration, and -0.55 and -0.69 for the relationship between wood density and Pilodyn values of radial penetration.

Key words: ancient architecture, larch, pine, wood decay, Pilodyn, quantitative analysis