A numerical method to integrate duration-of-load and bacterial deterioration for long-standing timber piles

Abstract

The strength degradation resulting from duration-of-load (DOL) effect and bacterial decay poses significant challenges to historical timber piles. Many historical European cities still heavily rely on the infrastructure supported by their original timber foundations. A reliable modelling approach on the structural performance of timber piles is needed to avoid the economic loss caused by closing down infrastructure. In this work, we consider a simplified bacterial decay model and develop a numerical framework to integrate the decay model into a standard DOL model. Two approaches are proposed and compared: one considering the homogenised effect of bacterial decay over the entire cross section, and the other taking into account the localised failure accelerated by bacterial decay and applying stiffness reduction to allow stress redistribution. Although the homogenised failure criterion is found to potentially underestimate the effect of bacterial decay, both approaches are able to capture the designated decay pattern. Ultimately, there is a potential for future extension to more intricate loading conditions and decay patterns.