Interpretation of Results of Penetration Tests Performed on Timber Structures in Bending

Abstract

The paper concentrates on the determination of local elastic moduli of timber in the fiber direction. To that end a single commercially produced glued timber beam was subjected to 3600 penetration measurements. The beam was first covered by a regular grid of monitoring points at which the depth of indentation was measured. The pin was shot into the wood with a given energy (Pilodin 6J). At the same time the moisture content at 80 selected points was determined. A specific measurement order was assumed to exclude principal measurement errors on the one hand and to minimize systematic measurement errors on the other. We expect the measured elastic moduli to serve as an input for advanced finite element simulations on the bases of stochastic analysis. In such a case the local measured moduli represent in a given segment of each lamella an ensemble of data characterized by a selected probability distribution. These distributions are then employed in the LHS based stochastic simulation to provide probability distribution of the maximum deflection for a given load level. Apart from that it appears meaningful to compare independently the probability distributions of the elastic moduli for segments of the lamella (these may considerably differ owing to the specifics of the production of structures made from glued lamella timber) with statistical data from the whole beam. Based on the measured data the correlation matrix relating statistical dependence of individual segments can be estimated thus improving the quality of the stochastic model.