International Nondestructive Testing and Evaluation of Wood Symposium
September 24-27, 2013, Madison, Wisconsin, USA
The purpose of this study was to explore the possibilities of using existing nondestructive evaluation (NDE) methods to assess delamination and decay of glulam structures. A glulam arch removed from a research building after more than 75-year service was used as a test specimen. The glulam arch section was tested using stress wave timing, ultrasonic wave propagation, and resistance microdrilling methods at a series of locations. The arch was subsequently cut open for visual inspection and small compression and shear samples were obtained for strength testing. It was found that wave propagation times or wave velocities measured across the laminations were good indicators of internal decay. Stress wave timing and ultrasonic propagation methods were able to detect moderate to large delamination, but not micro-delamination. Resistance micro-drilling was found not effective in detecting delamination. Further research is planned to evaluate the possibility of using pulse-echo method to detect internal delamination of glulam members. Key words: glued laminated timber (glulam), stress wave, ultrasonic wave, resistance micro-drilling, strength, modulus of elasticity.