A multi-Fickian model to simulate the hygro-thermal behaviour of stress-laminated timber decks

The hygro-thermal behaviour of timber bridges exposed to continuously variable climates is a fundamental topic for their durability, serviceability and safety. High daily humidity variations and large moisture changes at high levels of relative humidity RH provide large moisture gradients. The use of computational hygro-thermal methods can be useful, alongside with sensor techniques, for monitoring relative humidity and temperatures in timber structures. A multi-Fickian model was previously implemented in Abaqus FEM code and verified for wooden members under Southern Europe climates. The model was able to simulate the moisture states in each point of a wooden member by using as external loads the relative humidity and temperature of the air provided by in-situ measurements or by close meteorological stations. In the present work a variant of the model is developed to take into account the higher RH variations as well as the negative temperatures in Northern Europe environments. The model is used to numerically simulate the hygro-thermal response of stress-laminated timber decks in Norwegian timber bridges.