Wooden pile foundations are present in many historic towns in Europe and beyond. The technology for making such foundations was developed primarily in southern Europe but spread rapidly to other locations, with ever-better-performing technologies for creating them. In the area of Venice, Italy, the piles are relatively short, whereas in many cities around the Netherlands, the wooden piles can be up to around 15 m. Oftentimes, horizontal wood members are placed on top of the piles, acting as the structural interface between the upper structure and the piles. Many of the current foundations in Amsterdam and other medieval cities in the Netherlands were built from 1600 onwards. As there are indications that their end-of-service life is nearing, assessing the state of the wood, its mechanical properties, and the remaining load-carrying capacity is fundamental, as the economic consequences of failure of foundations below bridges, quay walls, and buildings can be colossal. Consequently, a fundamental analysis is required, addressing the type and extent of mechanical degradation resulting from long-term loading (duration of load effect), in combination with an assessment of the size and severity of biological or physical decay. The combined effect is responsible for the remaining load-carrying capacity and, consequently, for the remaining service life or for the assessment of possible reuse of the foundation. The assessment of this remaining load-carrying capacity is performed using an integral damage accumulation model, which takes into account the severity of time-dependent biological degradation and the wood quality, as measured by underwater micro-drilling, combined with the mechanical load components (dead load, traffic loads), and the duration of the load effect. As such, the structural analysis approach differs from current design standards for new timber structures and aligns with the principles outlined in ISO Standard 13822 for the assessment of existing structures.
KUILEN et al. (Wed,) studied this question.