Timber elements within historic structures are often susceptible to biological decay caused by insects. The areas affected by insect attacks are typically not considered in the structural analysis, although they may still provide some strength. Hence, accurately assessing the extent and intensity of insect damage is crucial for determining the actual strength of timber members. The present work presents the results obtained on insect-damaged timber members that were evaluated based on the proportion of the surface area occupied by bore holes, a method that is readily applicable by skilled operators during on-site inspections. Resistance to penetration (by drilling) and standard mechanical tests were then carried out to measure density in addition to strength (compression, shear, bending) and modulus of elasticity in bending. The results evidenced moderate yet highly significant inverse correlations between degree of degradation and mechanical properties. In contrast, density showed no discernible correlation with the degree of decay, nor did penetration resistance. However, drilling resistance showed a robust correlation with density and mechanical characteristics. The coupling between visual assessment of decay and evaluation of resistance to penetration allowed accurate prediction of mechanical properties similar to healthy wood.

Evaluation of Timber Degradation Caused by Insects to Quantify the Mechanical Strength of Load-Bearing Elements

Brunetti, Michele;Aminti, Giovanni;Pizzo, Benedetto;Vicario, Margherita;Nocetti, Michela
2023

Abstract

Timber elements within historic structures are often susceptible to biological decay caused by insects. The areas affected by insect attacks are typically not considered in the structural analysis, although they may still provide some strength. Hence, accurately assessing the extent and intensity of insect damage is crucial for determining the actual strength of timber members. The present work presents the results obtained on insect-damaged timber members that were evaluated based on the proportion of the surface area occupied by bore holes, a method that is readily applicable by skilled operators during on-site inspections. Resistance to penetration (by drilling) and standard mechanical tests were then carried out to measure density in addition to strength (compression, shear, bending) and modulus of elasticity in bending. The results evidenced moderate yet highly significant inverse correlations between degree of degradation and mechanical properties. In contrast, density showed no discernible correlation with the degree of decay, nor did penetration resistance. However, drilling resistance showed a robust correlation with density and mechanical characteristics. The coupling between visual assessment of decay and evaluation of resistance to penetration allowed accurate prediction of mechanical properties similar to healthy wood.
2023
Istituto per la BioEconomia - IBE
Biological damage; drilling resistance; historical timber structures; in-situ survey; mechanical properties; visual assessment
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.14243/509233
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