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At present, the mechanical properties of laterally loaded threaded fasteners with large diameters embedded in timber elements remain unknown. An experimental study of laterally loaded threaded rods with wood screw threads embedded perpendicular to grain in softwood elements (spruce and pine glulam and spruce LVL) is presented in this paper. Embedment tests with the load acting parallel and perpendicular to grain were carried out and the embedment strength and stiffness were quantified. For some test series, the experimental embedment strengths were lower compared to the predictions according to Eurocode 5 in terms of both mean and characteristic values. This finding indicates that the predictions by Eurocode 5 are not always conservative. To investigate the effect of the thread, additional series of embedment tests were carried out with smooth dowels featuring a diameter approximately equal to the core diameter of the threaded rods. Finally, the yielding moment of threaded rods was quantified based on a series of three-point bending tests of threaded rods. The experimentally determined yielding moment was significantly higher than the prediction of Eurocode 5.

The mechanical behaviour of timber loaded in compression perpendicular to grain is essential for a rational design of many timber structures. Structural components frequently exposed to such loading include studs on bottom rails, stress-laminated timber decks, timber elements lying in between vertical load-bearing columns as well as traditional timber joints mating surfaces in compression. Compression perpendicular to grain has been a repeated topic for discussion both in the current European regulations for timber structures, as well as in the ongoing work with the next generation of Eurocode 5 -timber structures. However, the long-term behaviour is quite complex, taking both time and moisture variation into consideration, and to improve the understanding and the ability to consider the long-term effects in practical design, a simplified one-dimensional model is given herein. The paper presents novel results from long-term compression orthogonal to grain tests performed with load and moisture control. The purpose of the testing was to evaluate the effect of transversal creep on the long-term behaviour of timber elements including the effect of the mechanosorptive deformation. The test results were in turn used to calibrate a one-dimensional model for the prediction of the long-term response of timber. The model takes into account the combined effects of loading and moisture variations. The effective material properties are defined by use of effective pith locations together with the orthotropic material parameters. Finally, a comparison between the model results and experimental observations is given, showing an overall good prediction of the response.

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The effects of variation in humidity coupled with long-term loading give rise to dimensional changes and creep effects in wooden elements. Many wooden products such as cross-laminated timber (CLT) plates as well as many common structural details used in timber engineering are vulnerable to variations in moisture content (MC) as well as to creep effects. This paper addresses the long-term effects in the material modelling of timber by the finite element method (FEM), also considering the viscoelastic and mechanosorptive effects in wood. The model was calibrated using both relaxation tests and creep tests. The results from both long-term compression perpendicular- to-grain tests (relaxation and creep) performed on glulam (GL30c) from Norway spruce (Picea abies) with moisture control are presented in this paper. The material model considers the effect of loading and moisture changes. For realistic comparison, the pith location of each lamella was specified in the numerical analyses. Ultimately, a comparison between the numerical results and the experimental results has been provided, exhibiting an overall good estimation of timber response.