Structural performance of rounded dovetail connections: experimental and numerical investigations

Abstract

Rounded Dovetail Connections (RDC) are a relatively new wood-to-wood connection concept that, despite the lack of design guidance in standards, has become popular in timber construction due to the widespread of modern milling machinery. Because of the anisotropic nature of wood and the complex stress-strain state in RDC, the question of their dimensioning is very complex. Experimental and numerical investigations were carried out on full scale RDC used to connect two timber members as joist to beam connections subjected to quasi-static shear loading. The influence of two geometric parameters was investigated: the dovetail height (varied between 109 and 189 mm) and the flange angle (varied between 5 and 20°). Both, serviceability and ultimate limit states were studied using analysis of variance. It was found that the joint capacity (i) depends on the dovetail height, with an optimum of approximately 2/3 of the beam height and (ii) can be considered almost independent of the flange angle. The development and implementation of a numerical model for the design process of RDC was examined and good agreement between experimental and numerical load deformation curves validated the model, thus making it suitable for developing a method to predict RDC capacity. The paper proposes a probabilistic method to predict the capacity of RDC taking into account the scale sensitivity of the material strength, which is modelled using Weibull statistics, and considers not only the magnitude of the stress fields, but also the volume over which these stress peaks act. The proposed method has immediate actionable application for the improvement of RDC design. Tragverhalten von

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“…Rounded Dovetail Joints (RDJs) are a versatile concept for connecting structural timber members, with the most common application being joist to beam connections. A number of experimental and analytical studies [12][13][14][15][16] provided valuable insight revealing that RDJ failure under shear loading is typically brittle, initiates at the bottom of the dovetail of the joist member, and occurs at load levels much below the member strength. Furthermore, the relative vertical deformation between members may reach considerably high values (approx.…”