Service life design of timber structures

Abstract

[Excerpt] Wood has been widely used by humans as a construction material for millennia and can be easily found in everyday life, all around the world. Wood as a material can be defined as a natural, sustainable, and organic composite characterized by its hygro scopic behavior, orthotropic constitution, and variable natural durability. As with every organic material, wood can be affected by several types of deterio ration agents under suitable climate exposure conditions, which usually entails bio logic degradation and physical and chemical damage. Once it appears, wood deterioration can compromise at different levels the safety and long-term performance of timber structures, by reducing their service life. Therefore, it is crucial to spot and prevent the development of different wood deterioration agents likely to occur in tim ber structures in service per their climate exposure conditions. In that context, the present chapter aims at providing notions, guidelines, and cur rent research to help engineers and architects when designing the service life of timber structures. All wood-deteriorating agents must be clearly defined and evaluated when assessing the performance of timber structures, by determining their emergence and development conditions according to the climate factors (e.g., temperature, air relative humidity, wood moisture content, etc.). Since they condition the occurrence risk of biologic degradation, the natural durability of wood and use class must be determined through standard methodologies to correctly use the properties of every wood species as a construction material, with respect to climate factors, and especially to moisture exposure. In addition to these guidelines, durability models may be proposed to predict the risk of wood deterioration and the loss of performance of timber structures during their service life. [...]