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Keywords: shear walls, wall diaphragms, finite element modelling, plastic shear connector.

Summary

Light-frame timber buildings are often stabilised against lateral loads by using the diaphragm action of roofs, floors and walls. The mechanical behaviour of the sheathing-to-timber joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints demonstrate non-linear load-displacement characteristics with plastic behaviour. Brittle characteristics may occur in some cases, e.g. when edge distances in the sheathing and framing materials are small and the forces act perpendicular to the edges. However, if only a few of the sheathing-to-timber joints show brittle failure modes, the overall behaviour of the shear wall is anyhow fairly plastic.

For the design of shear walls, analytical methods based on elastic or plastic characteristics of the sheathing-to-timber joints are often used. In order to carry out more accurate calculations, linear or non-linear finite element analyses need to be conducted. This paper is focused on the finite element modelling of shear walls.

The paper presents a new connector shear element based on the general theory of plasticity. The derivation of the relationship between incremental force and incremental deformation is illustrated. The actual connector behaviour and the pertaining different plastic properties are determined from the test results.

The model for the incremental stress versus strain relationship is based on a tangential elastic-plastic stiffness tensor, which includes the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion, and another function representing the plastic potential. The two functions mentioned are usually assumed to be equal giving an associated flow rule for a given yield criterion.

The shear element under consideration has only two shear stress components or the two corresponding connector forces in the plane. A scalar effective connector force and a yield function including a yield force according to a hardening rule are defined.

The new plastic connector shear model is evaluated with respect to the horizontal load-displacement behaviour of a single segment shear wall and compared with corresponding test results and with other computer results presented in the literature (using non-linear spring models). Also, the ultimate horizontal load-carrying capacity of the shear wall is compared with the new analytical plastic design method developed by the authors [1].

The calculated curves are on the safe side with respect to the test results and there is a very good agreement between the load-carrying capacity between that obtained by the connector shear model and that by the analytical plastic design method.

References

1: B. Källsner, U.A. Girhammar, "Plastic design of partially anchored wood-framed wall diaphragms with and without openings", Proceedings CIB-W18 Meeting, Karlsruhe, Germany, 2005.

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 93 PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: Paper 246 Finite Element Modelling of Shear Walls using Connector Shear Elements based on Continuum Plasticity U.A. Girhammar^1,2, P.J. Gustafsson³ and B. Källsner^4,5 ¹Division of Structural Engineering - Timber Structures, Luleå University of Technology, Sweden ²Division of Building Engineering, Department of Applied Physics and Electronics, Faculty of Science and Technology, Umeå University, Sweden ³Division of Structural Mechanics, Department of Building Sciences, Lund Institute of Technology, Lund University, Sweden ⁴School of Engineering, Linnæus University, Växjö, Sweden ⁵SP Technical Research Institute of Sweden, Stockholm, Sweden doi:10.4203/ccp.93.246 purchase the full-text of this paper Full Bibliographic Reference for this paper , "Finite Element Modelling of Shear Walls using Connector Shear Elements based on Continuum Plasticity", in , (Editors), "Proceedings of the Tenth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 246, 2010. doi:10.4203/ccp.93.246 Keywords: shear walls, wall diaphragms, finite element modelling, plastic shear connector. Summary Light-frame timber buildings are often stabilised against lateral loads by using the diaphragm action of roofs, floors and walls. The mechanical behaviour of the sheathing-to-timber joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints demonstrate non-linear load-displacement characteristics with plastic behaviour. Brittle characteristics may occur in some cases, e.g. when edge distances in the sheathing and framing materials are small and the forces act perpendicular to the edges. However, if only a few of the sheathing-to-timber joints show brittle failure modes, the overall behaviour of the shear wall is anyhow fairly plastic. For the design of shear walls, analytical methods based on elastic or plastic characteristics of the sheathing-to-timber joints are often used. In order to carry out more accurate calculations, linear or non-linear finite element analyses need to be conducted. This paper is focused on the finite element modelling of shear walls. The paper presents a new connector shear element based on the general theory of plasticity. The derivation of the relationship between incremental force and incremental deformation is illustrated. The actual connector behaviour and the pertaining different plastic properties are determined from the test results. The model for the incremental stress versus strain relationship is based on a tangential elastic-plastic stiffness tensor, which includes the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion, and another function representing the plastic potential. The two functions mentioned are usually assumed to be equal giving an associated flow rule for a given yield criterion. The shear element under consideration has only two shear stress components or the two corresponding connector forces in the plane. A scalar effective connector force and a yield function including a yield force according to a hardening rule are defined. The new plastic connector shear model is evaluated with respect to the horizontal load-displacement behaviour of a single segment shear wall and compared with corresponding test results and with other computer results presented in the literature (using non-linear spring models). Also, the ultimate horizontal load-carrying capacity of the shear wall is compared with the new analytical plastic design method developed by the authors [1]. The calculated curves are on the safe side with respect to the test results and there is a very good agreement between the load-carrying capacity between that obtained by the connector shear model and that by the analytical plastic design method. References 1 B. Källsner, U.A. Girhammar, "Plastic design of partially anchored wood-framed wall diaphragms with and without openings", Proceedings CIB-W18 Meeting, Karlsruhe, Germany, 2005. purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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