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Creep deformation influences the serviceability limit state as well as the ultimate limit state of timber structures. In order to consider this time-dependent behavior, creep coefficients and rheological models have been developed by various researchers. Comparing the rheological models, quite different temporal deformations are evaluated for a duration of load of 50 years. In order to find the model, which is most suitable to the situation in the region of Tübingen, South-West Germany, the existing deformations of several beams in roof structures in opened, protected but not heated buildings are measured. By loading the structure the elastic global stiffness of the particular element is determined. So creep coefficients can be evaluated, which should have been used by the engineer in order to get the existing deflection after 50 years. Within the region of Tübingen, on average a creep coefficient of 2.23 was found based on these measurements. However, the standard deviation of 0.97 is quite large. For the numerical evaluation of the time-dependent behavior Toratti´s model is modified, so that it matches the measured deformations.

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Jörg Schänzlin was working at the Institute of Structural Design at the University of Stuttgart until 2009. During this time he focused on the determination of the long term behavior of structural timber, summarizing these studies in his habilitation in 2010. Since 2009 he is working at the Konstruktionsgruppe Bauen AG, Kempten.

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