Timber connections with steel dowel-type fasteners may fail in ductile or brittle ways. The design of this joints was traditionally focused on ductile failure, assuming that brittle failure could be avoided by means of geometrical limitations. However, recent studies demonstrated that these assumptions do not always guarantee ductile failure. A new design model for timber connections with small diameter dowel-type fasteners is provided in this paper. Its improved accuracy is demonstrated by analysing an extensive database of experimental tests and comparing its prediction accuracy to that of existing models.

Timber connections with small diameter fasteners that do not go through the whole timber member (such as screws or nails). may fail in brittle or ductile ways. In order to better understand their behaviour, an experimental campaign of tests of connections with small diameter fasteners loaded parallel-to-grain has been performed. The results and analysis of this work provide further information on the role of different parameters in the brittle failure. Existing models are benchmarked against these tests.

Timber connections can fail in a ductile or in a brittle way. A structural design that guarantees a ductile behaviour in case of failure is desirable, especially when facing extreme situations such as earthquakes. This work discusses how the European Yield Model (based on a ductile failure mechanism), included in many standards, combined with a reduction of the effective number of fasteners may provide too conservative results, which may inadvertently lead to risky situations in which a connection assumed to fail under a ductile mechanism would actually fail in a brittle manner. Within this paper, a proposal to improve the discrimination ability to correctly predict the failure mode is proposed.

The consideration of brittle failure of timber connections requires an adequate evaluation of the capacity of the involved failure planes. Their correct geometrical definition is therefore of utmost importance to obtain an accurate assessment of their capacity. This article presents a new approach to account for the effective thickness of the lateral planes of timber members in connections with large diameter fasteners loaded parallel-to-grain when the fasteners remain in its elastic range, which allows to consider the uneven load distribution along the fastener in a simple way. The proposal is based on a fitting of a beam on elastic foundation model and only requires the slenderness of the fastener as a parameter. It provides a both simple and accurate way to calculate the effective thickness of timber elements.

Timber connections may collapse in a brittle or in a ductile mode. The calculation models of timber joints are mainly focused on ductile failure mode, since it has been traditionally assumed that brittle failure was avoided by respecting a minimum spacing between fasteners. However, this assumption alone does not guarantee a ductile failure. This paper proposes a new design model dealing with brittle failure modes of timber connections with large diameter fasteners (those protruding the whole thickness of the timber member such as dowels or bolts). A comparison between the proposal and the existing models, using an extensive database of tests, is used to demonstrate the improved accuracy of the proposed design method.