Abstract:

The local damages such as knots, decay, and cracks can be translated into a reduction of service life due to mechanical and environmental loadings. In wood construction, it is very important to evaluate the weakest location and detect damage at the earliest possible stage to avoid the future catastrophic failure. In this study, the modal testing was operated on wood beams to generate the first two mode shapes. A novel statistical algorithm was proposed to extract the damage indicator by computing the modal flexibility curvature before and after damage in timbers. The different damage severities, damage locations, and damage counts were simulated by removing mass from intact beams to verify the algorithm. The results showed that the proposed statistical algorithm was effective and suitable to the designed damage scenarios. It was reliable to detect and locate local damages under different severities, locations, and counts. The peak values of the damage indicators computed from the first two mode shapes were sensitive to different damage severities and locations. They were also reliable to detect the multiple damages.

Key words: damage detection, sawn timber, modal flexibility