An experimental and numerical study of the effect of friction in single dowel joints

Sjödin, Johan; Serrano, Erik; Enquist, Bertil

doi:10.1007/s00107-008-0267-z

Cited by 71 publications

(41 citation statements)

References 5 publications

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“…Only a limited number of numerical models is applied to wide connections, in which dowel bending is crucial [15,16]. The influence of friction on the mechanical behavior of the connection has been studied in experiments as well as in simulations [17]. Typically, static friction coefficients between 0.1 to 0.7 are assumed in the simulations, which is a parameter heavily influencing load capacity and the occurrence of brittle failure, but not thoroughly verified experimentally.…”

Section: State Of the Artmentioning

confidence: 99%

Experiments on dowel-type timber connections

Dorn

Borst

Eberhardsteiner

2013

Engineering Structures

102

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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

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Section: State Of the Artmentioning

confidence: 99%

Experiments on dowel-type timber connections

Dorn

Borst

Eberhardsteiner

2013

Engineering Structures

102

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“…Additionally, Sandhaas et al (2013) revealed an influence of the steel quality, which was most probably related to the surface roughness. The strong effect of the steel dowel surface roughness was also shown by Sjödin et al (2008). Another effect that might contribute to a higher risk for splitting is the rather large width of the test specimen.…”

Section: Unreinforced Reference Specimensmentioning

confidence: 61%

Influence of different types of reinforcements on the embedment behavior of steel dowels in wood

et al. 2016

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In this study, dowel displacement-embedment stress relationships for different types, numbers and positions of reinforcements were experimentally investigated using a half-hole embedment test setup. Tests were performed parallel to the grain and in compression. Screws with a full or partial thread at different positions below the dowel and oriented strand board, plywood and nail plates on the loaded surfaces of the specimens, served as reinforcements. Test results underline their potential for an increased ductility of dowel-type connections. Comparison of reinforced and unreinforced specimens suggests premature failure of the unreinforced wood and consequently, an underestimation of the embedment strength as it is subsequently used in the design of dowel connections using the European yield model. This was supported by the investigation of cracks on the surface of the specimens visualized by means of a full-field deformation measurement system. It could be demonstrated that the strength in the embedment test even further increases if the reinforcement elements actively contribute to the load transfer. This property however cannot be considered as embedment strength, but represents the strength of a connection system. Test data is compared to the design equation in Eurocode 5.

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“…When a bolt with a rough surface was used in bolted joints, the experimental results showed that the friction between the bolt and wood was increased [21,22]. The maximum load of a bolted joint with a rough surface and an l/d ratio of approximately one was 1.2-1.4 times as large as that with a smooth surface.…”

Section: Factors Governing Materials Characteristicsmentioning

confidence: 98%

Strength of bolted timber joints subjected to lateral force

Sawata

2015

J Wood Sci

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The safety and serviceability of timber structures are frequently governed by the performance of joints. Bolted joints are a very commonly used form of joints and are effective from the viewpoint of the load-slip characteristics when subjected to a lateral force. The shear strength of a bolted joint is affected by various factors. Some of the factors affecting the shear strength of a bolted joint are classified into four categories in this paper: the material characteristics, geometrical factors, assembly conditions for the bolted joint, and factors that act during its service. This paper reviews the effects of these factors on the shear strength of a bolted joint. Numerous experimental studies were performed on the shear strength of a bolted joint. The effects of these factors on the shear strength varied according to the kind of shear strength and loading direction to the grain. In addition to the experimental investigations, analytical investigations to estimate the shear strength of a bolted joint are also discussed in this paper. Estimations of the yield strengths of bolted joints have been performed by numerous researchers; and in recent years, there has been an increase in studies to predict the load at failure.

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An experimental and numerical study of the effect of friction in single dowel joints

Cited by 71 publications

References 5 publications

Experiments on dowel-type timber connections

Experiments on dowel-type timber connections

Influence of different types of reinforcements on the embedment behavior of steel dowels in wood

Strength of bolted timber joints subjected to lateral force

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