Partner und Internationale Organisationen
(Englisch)
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A, B, CZ, DK, FIN, F, D, GR, H, IRL, I, NL, N, P, RO, SI, E, S, CH, GB
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Abstract
(Englisch)
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The aim of this research project is to establish the basis for deriving a consistent set of probabilistic models for strength and stiffness related timber material properties and to calibrate corresponding partial safety factors such that the level of structural reliability for timber structures is equivalent to the safety of concrete and steel structures; this seen in the light of the ongoing revision of the national Swiss Codes for the design of structures. The probabilistic modelling of resistance related timber material properties, in a short term- and in a long term perspective, is of particular relevance for the past and ongoing research. In recent studies the probabilistic modeling of timber connections was considered: In the common design standards, as the Eurocode 5 (EN1995-1-1) and the SwissCode (SIA 265) the Johansen model is presented to predict the strength of connections with dowel-type fasteners. This model contains besides a number of geometrical parameters two material parameters; the embedment strength of the timber and the yield moment of the fastener. Our study focuses on the main influencing independent parameters of the embedment strength being; the timber density and diameter of the fastener. Embedment test results from the literature are considered to create a probabilistic framework for the prediction of the embedding strength. The presented framework is applied in a reliability analysis of a simple dowel connection. The lower 5%-Fractile of the embedding strength is introduced to characterize the evaluated probability distribution of the embedding strength. This information can be used to be incorporated in probabilistic design codes to feed design models of timber connections. The described study was performed during a so-called 'short term scientific mission' of Ad Leijten from Delft University at the Institute of Structural Engineering at ETH Zurich. The results of the study are published. An important issue of the COST action E24 is to draft a Probabilistic Model Code (PMC) for Timber Structures. In the last few month a proposal was prepared and frequently updated and refined. The present proposal of the PMC for timber structures mainly concerns modeling the material properties of solid structural timber. As a major output of the COST E24 action it is planned to finish the document within the this year 2005. Within the present project the following meetings were held in 2004: · Workshop COST Action E24, Florence, 27-28 May 2004. · 36th Meeting of the 'International Council for Research and Innovation in Building and Construction, CIB, Working Commission W18 - Timber Structures' Edinburgh, UK, 1.-03. September 2004. Presentation: J. Köhler, M.H. Faber 'Probabilistic Model Code for the Design of Timber Structures'; J. Köhler, A. Leijten, A. Jorissen 'Review of probability data for timber connections with dowel-type fasteners.' · Workshop COST Action E24, Zurich, 6-7 September 2004. · Workshop COST Action E24, Copenhagen, 29 November 2004. Within the present project the following meetings were held in 2004: Faber M.H., Köhler J. and Sorensen, J.D. 2004. Probabilistic Modeling of Graded Timber Material Properties. Journal of Structural Safety, Volume 26, Issue 3, Pages 241-366 (July 2004). Köhler J., Faber M.H. 2004. Proposal for a Probabilistic Model Code for the Design of Timber Structures. Proceedings International Council for Research and Innovation in Building and Construction, Working Commission W18 - Timber Structures, CIB-W18, 37th Meeting, Edinburgh, UK, Paper: 37-104-1. Leijten, A., Köhler J., Jorissen A. 2004. Review of Probability Data for Timber Connections with Dowel Type Fasteners. Proceedings International Council for Research and Innovation in Building and Construction, Working Commission W18 - Timber Structures, CIB-W18, 37th Meeting, Edinburgh, UK, Paper: 37-7-12.
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