Moisture induced stresses: numerical approaches and results

Wood as a hygroscopic material adapts to variations of relative humidity and temperature of its surrounding environment: it either releases moisture in a drying process or adsorbs during a wetting process. The distribution of the moisture content across load bearing elements is normally non-uniform (Dietsch et al. 2015, Fortino et al. 2019, Franke et al. (2019)). The subsequent hygro-expansion and (constrained) swelling and shrinkage generates moisture induced stresses (MIS). These stresses can exceed the allowable strength perpendicular to the grain and generate cracks. The load-carrying capacity are reduced, and visible appeal of timber structures are affected. Structures are built throughout the year and building processes span multiple months until a building envelope is closed. Damage can be already initiated before the building is opened for its intended use.