Simulation of moisture diffusion in timber bridges exposed to rain

The paper presents a modified single-phase numerical model of timber exposed to the external climate. The previous studies by some of the authors showed that finite element method (FEM) with the single-Fickian theory of moisture diffusion is an efficient tool to simulate the moisture gradients in timber structures sheltered from rain. An extension of this approach that takes into account the effect of water due to rain or water traps is proposed in this paper and the numerical model is verified by comparisons with laboratory tests of Norway spruce joints exposed to artificial rain in the laboratory of Lund University. The model is then used to simulate moisture diffusion in selected details of timber bridge elements monitored within the DuraTB project.