Detection and assessment of wood decay in glulam beams using a through-transmission ultrasonic approach

A glulam beam retired from the field and without visible indications of wood decay was used. Towards detection and assessing wood decay, X-ray computer tomography and ultrasonic measurements were carried out. It was observed that decrease in mass density with increasing levels of wood decay affects x-rays attenuation and allows radioscopy to detect and assess wood decay. Furthermore, it was also observed that the decrease in mass density and stiffness caused by wood decay affects ultrasonics measurements. It was observed that ultrasonic velocity and stress wave features such as time of arrival, area under the power spectral density curve, energy, and frequency of maximum amplitude allows detection and assessment of wood decay. Results show that results from both X-ray computer tomography and ultrasonic measurements are consistent with each other and can be used to detect and assess wood decay in structural lumber.