Influence of insect damage to the fatigue life of an old larch wood.

• The influence of age of larch wood on its strength was determined. • The influence of worm damage on the fatigue life of the wood was estimated. • A model for wood density equivalent fatigue life was developed. • The dynamic properties of larch wood are more affected by the aging process than the static properties. In many cultural heritage buildings, structural members are made of wood. Over the years, wood is exposed to various biotic and abiotic degradation factors, including moisture oscillations, mechanical stress, and insect and fungal decay. In the present respective study, an experimental study on the fatigue life of 350 years old larch wood was carried out. The fatigue life of the old wood was compared to the fatigue life of the recent larch wood. A statistical model for the fatigue-life curves and their scatter was built for both kinds of wood. The model can consider different factors to the fatigue life, e.g. wood density, specimen orientation during loading, and extent of insect damage. An equivalent number of load cycles to failure was also defined, enabling a direct comparison of the fatigue life data for specimens with different wood densities or orientations during loading. From the results, it can be concluded that the proposed statistical model adequately describes the fatigue behaviour of both the old, insect-damaged wood and the recent larch wood. [ABSTRACT FROM AUTHOR]