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Based on the equilibrium method of plasticity, the theoretical explanation of the bearing strengths of locally loaded timber blocks is given in the Appendices. The result of the numerical construction of the slip-lines can precisely be represented by an analytical function of a logarithmic spiral that can be shown to be the exact solution. This function in one variable can be given in the power law form leading to a theoretical and experimental value of that power of 0.5.This power representation of the stress spreading model of the strength increase, by confined dilatation, provides simple rules for the code and a simple design method that precisely matches to the data in all circumstances and loading cases and explains the apparent contradictory test results of Suenson, the Eurocode, the French rules, Graf, Korin and Augustin et al. and, as shown before, explains other comparable loading cases as e.g. by pin dowel connections (see literature). Bestimmung der Querdruckfestigkeit von Holz bei SchwellendruckZusammenfassung In den Anhängen wird auf Grundlage des Traglastverfahrens die Erklärung für die Querdruckfestigkeit von Holz bei Schwellendruck theoretisch hergeleitet. Die numerisch hergeleiteten Gleitlinien können analytisch als Funktion einer logarithmischen Spirale beschrieben werden. Es lässt sich zeigen, dass dies eine exakte Lösung darstellt. Diese Funktion mit einer Variablen T. A. C. M. van der Put (u) Faculty of Civil Engineering and Geosciences, Timber structures and wood technology, TU Delft,

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a b s t r a c tBased on the deformation kinetics approach, the theoretical derivation is given of the empirical WLFequation of the time-temperature equivalence. The same is done for annealing at glass transition. The derivation provides a general theory for any loading history and replaces the inconsistent free volume model.