Uncertainty of visual inspection on the reliability analysis of timber elements


Sousa, Hélder S.; Ribeiro, Sérgio; Matos, José C.; Branco, Jorge M.; Lourenço, Paulo B.

Visual inspection; Timber; Uncertainty; Reliability

In this work, the uncertainty related to the process of visual inspection of timber elements as a method to define different strength classes is quantified. For that aim, visual inspection was made to different chestnut timber elements at local and global scales. The inspection was made by sixteen different inspectors, with low experience, and by an expert for benchmark analysis. The uncertainty of the visual inspection process was measured by the analysis of these independent observations obtained under the same conditions of measurement, resulting in the quantification of the experimental standard deviation to characterize the variability of the observed values and of the experimental standard deviation of the mean to characterize the uncertainty of the process. A reliability analysis was also made using random samples including the uncertainty from the visual inspection process, obtaining reduction factors for a specific case study.