Determining main mechanical properties of ancient architectural timber

During maintenance of ancient wood architectures, it is critical to non-destructively and effectively determine the residual mechanical properties of key wood structural members, so that degraded members may be replaced or repaired to avoid structural failure. Experimental materials used in this study were larch (Larix principis-rupprechtii) timber samples taken from the drum-tower of Zhengjue Temple of Yuanmingyuan (Old Summer Palace) in Beijing. The timber samples were cut into standard specimens first, and then stress wave measurements, micro-drilling tests and density tests were conducted. Product of resitograph and stress wave speed squared is defined as modulus of stress-resistograph in this study. We conducted static bending and compression parallel to grain tests on the standard specimens to determine the modulus of elasticity, bending strength and compression strength. Our analysis indicated that the modulus of stress-resistograph had good linear regression relationships with modulus of elasticity (MOE), modulus of rupture (MOR) as well as compression strength, and the coefficients of determination were 0.505 6, 0.260 9 and 0.477 3 respectively. In order to better evaluate the main residual mechanical properties with parameter of the modulus of stress-resistograph, 95% confidence regression equations are suggested to be used in real situation.