Dowel-type connections are commonly used in timber engineering for a large range of structural applications. The current generation of design rules is largely based on empiricism and testing and lacks in many parts a stringent mechanical foundation. This often blocks an optimized use of the connections, which is essential for the design of economically efficient structures. Moreover, it severely limits the applicability of the design rule, such as restrictions regarding splitting behavior or maximum ductility (e.g. maximum allowable deformations) are missing. Therefore, the demands due to a large and quickly evolving variety of structural designs in timber engineering are not reflected.The aim of this work is to study the load-carrying behavior of the connection in detail, including all loading stages, from the initial contact between dowel and wood up to the ultimate load and failure. Distinct features during first loading as well as during unloading and reloading cycles are identified and discussed. The knowledge of the detailed load-carrying behavior is essential to understanding the effects of individual parameters varied in relation to the material and the connections design. The suitability of the current design rules laid down in Eurocode 5 (EC5) is assessed and deficiencies revealed.Tests on 64 steel-to-timber dowel-type connections loaded parallel to the fiber direction were performed. The connections were single-dowel connec- tions with dowels of twelve millimeter diameter. The test specimens varied in wood density and geometric properties. Additionally, the effects of dowel roughness and lateral reinforcement were assessed. The experiments confirmed that connections of higher density show significantly higher ultimate loads and clearly evidenced that they are more prone to brittle failure than connections using light wood. The latter usually exhibit a ductile behavior with an extensive yield plateau until final failure occurs. With increased dowel roughness, both, ultimate load and ductility are increased.The test results are compared with corresponding design values given by EC5 for the strength and the stiffness of the respective single-dowel connections. For connections of intermediate slenderness, EC5 provided conservative design values for strength. Nevertheless, in some of the experiments the design values overestimated the actual strengths considerably in connections of low as well as high slenderness. As for the stiffness, a differentiation according to the connection width is missing, which gives useful results only for intermediate widths.Furthermore, the test results constitute valuable reference data for validating numerical simulation tools, which are currently a broad field of intensive interest.Keywords: dowel-type timber connections, Johansen theory, uniaxial tension tests on connections, ductile and brittle failure modes, influence of density, connection design and dowel roughness, comparison with design rules in Eurocode 5
The increased prevalence of autism spectrum disorders (ASD), with associated societal and clinical impacts, calls for a broad community-based dialogue on treatment related ethical and social issues. The Stony Brook Guidelines, based on a community dialogue process with affected individuals, families and professionals, identify and discuss the following topics: treatment goals and happiness, distributive justice, managing the hopes for a cure, sibling responsibilities, intimacy and sex, diagnostic ethics, and research ethics. Our guidelines, based not on "top-down" imposition of professional expertise but rather on "bottom-up" grass roots attention to the voices of affected individuals and families speaking from experience, can inform clinical practice and are also meaningful for the wider social conversation emerging over the treatment of individuals with ASD.
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