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Källsner, Bo
Publications (10 of 70) Show all publications
Caprolu, G., Girhammar, U. A. & Källsner, B. (2017). Analytical models for splitting capacity of bottom rails in partially anchored timber frame shear walls based on fracture mechanics. Wood Material Science & Engineering, 12(3), 165-188
Open this publication in new window or tab >>Analytical models for splitting capacity of bottom rails in partially anchored timber frame shear walls based on fracture mechanics
2017 (English)In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 12, no 3, p. 165-188Article in journal (Refereed) Published
Abstract [en]

Plastic design methods can be used for determining the load-carrying capacity of partially anchored shear walls. For such walls, the leading stud is not fully anchored against uplift and tying down forces are developed in the sheathing-to-framing joints and the bottom rail will be subjected to crosswise bending, leading to possible splitting failure of the rail. In order to use these plastic design methods, a ductile behaviour of the sheathing-to-framing joints must be ensured. In two earlier experimental programmes, the splitting failure capacity of the bottom rail has been studied. Two brittle failure modes occurred during testing: (1) a crack opening from the bottom surface of the bottom rail and (2) a crack opening from the side surface of the bottom rail. In this article, a fracture mechanics approach for the two failure modes is used to evaluate the experimental results. The comparison shows a good agreement between the experimental and analytical results. The failure mode is largely dependent on the distance between the edge of the washer and the loaded edge of the bottom rail. The fracture mechanics models seem to capture the essential behaviour of the splitting modes and to include the decisive parameters.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
Keywords
Bottom rail, splitting of bottom rail, timber shear walls, partially anchored
National Category
Civil Engineering
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-64435 (URN)10.1080/17480272.2015.1075228 (DOI)000399667800006 ()
Available from: 2017-05-29 Created: 2017-05-29 Last updated: 2018-04-04Bibliographically approved
Girhammar, U. A., Gustafsson, P. J. & Källsner, B. (2017). Modeling of shear walls using finite shear connector elements based on continuum plasticity. Frontiers of Structural and Civil Engineering, 11(2), 143-157
Open this publication in new window or tab >>Modeling of shear walls using finite shear connector elements based on continuum plasticity
2017 (English)In: Frontiers of Structural and Civil Engineering, ISSN 2095-2430, E-ISSN 2095-2449, Vol. 11, no 2, p. 143-157Article, review/survey (Refereed) Published
Abstract [en]

Light-frame timber buildings are often stabilized against lateral loads by using diaphragm action of roofs, floors and walls. The mechanical behavior of the sheathing-to-framing joints has a significant impact on the structural performance of shear walls. Most sheathing-to-framing joints show nonlinear load-displacement characteristics with plastic behavior. This paper is focused on the finite element modeling of shear walls. The purpose is to present a new shear connector element based on the theory of continuum plasticity. The incremental load-displacement relationship is derived based on the elastic-plastic stiffness tensor including the elastic stiffness tensor, the plastic modulus, a function representing the yield criterion and a hardening rule, and function representing the plastic potential. The plastic properties are determined from experimental results obtained from testing actual connections. Load-displacement curves for shear walls are calculated using the shear connector model and they are compared with experimental and other computational results. Also, the ultimate horizontal load-carrying capacity is compared to results obtained by an analytical plastic design method. Good agreements are found.

Place, publisher, year, edition, pages
Higher Education Press, 2017
Keywords
shear walls, wall diaphragms, finite element modelling, plastic shear connector, analytical modelling, experimental comparison
National Category
Civil Engineering
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-79197 (URN)10.1007/s11709-016-0377-3 (DOI)000401744300002 ()
Available from: 2018-12-13 Created: 2018-12-13 Last updated: 2018-12-13Bibliographically approved
Girhammar, U. A., Jacquier, N. & Källsner, B. (2017). Stiffness model for inclined screws in shear-tension mode in timber-to-timber joints. Engineering structures, 136, 580-595
Open this publication in new window or tab >>Stiffness model for inclined screws in shear-tension mode in timber-to-timber joints
2017 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 136, p. 580-595Article in journal (Refereed) Published
Abstract [en]

A stiffness model for inclined screws in timber joints, or as shear connectors in composite timber-to timber members, is presented. Elastic conditions applicable to the initial or linearized part of the load deformation response in the serviceability limit state are assumed. The model for the stiffness or slip modulus is general in nature; it includes both the dowel (or shearing) action and withdrawal action of the screw, the friction between the members and it takes into account possible dissimilar properties and geometries of the different parts of the joint configuration. The model is simplified in the sense that the screw is assumed rigid and the withdrawal stresses along the length of the screw are assumed evenly distributed. However, the effects of flexibility and extensibility of the screw are taken into account by applying a theoretically derived correction factor for the embedment and withdrawal stiffness modulus, respectively. The proposed model is illustrated showing the total stiffness versus the inclination, as well as the relative contributing effect from the shearing and withdrawal stiffness, respectively, the influence of the friction coefficient. Also, the effect of dissimilar properties and geometries between the two parts of the joint is illustrated. Experimental verification of the proposed model is also given. Comparisons with other stiffness models are also made. (C) 2017 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Timber-to-timber connections, Stiffness, Slip modulus, Dowel action, Withdrawal action
National Category
Civil Engineering
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-64191 (URN)10.1016/j.engstruct.2017.01.022 (DOI)000395611400042 ()
Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2018-06-05Bibliographically approved
Girhammar, U. A. & Källsner, B. (2017). Tests and Analyses of Slotted-In Steel-Plate Connections in Composite Timber Shear Wall Panels. Advances in Civil Engineering / Hindawi, Article ID 7259014.
Open this publication in new window or tab >>Tests and Analyses of Slotted-In Steel-Plate Connections in Composite Timber Shear Wall Panels
2017 (English)In: Advances in Civil Engineering / Hindawi, ISSN 1687-8086, E-ISSN 1687-8094, article id 7259014Article in journal (Refereed) Published
Abstract [en]

Theauthors present an experimental and analytical study of slotted-in connections for joining walls in the Masonite flexible building (MFB) system. These connections are used for splicing wall elements and for tying down uplifting forces and resisting horizontal shear forces in stabilizing walls. The connection plates are inserted in a perimeter slot in the PlyBoard (TM) panel (a composite laminated wood panel) and fixed mechanically with screw fasteners. The load-bearing capacity of the slotted-in connection is determined experimentally and derived analytically for different failure modes. The test results show ductile postpeak load-slip characteristics, indicating that a plastic design method can be applied to calculate the horizontal load-bearing capacity of this type of shear walls.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2017
National Category
Civil Engineering
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-72188 (URN)10.1155/2017/7259014 (DOI)000397900900001 ()
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-04Bibliographically approved
Girhammar, U. A. & Källsner, B. (2016). Design against brittle failure of bottom rails in shear walls. Proceedings of the Institution of Civil Engineers: Structures and buildings, 169(10), 782-793
Open this publication in new window or tab >>Design against brittle failure of bottom rails in shear walls
2016 (English)In: Proceedings of the Institution of Civil Engineers: Structures and buildings, ISSN 0965-0911, E-ISSN 1751-7702, Vol. 169, no 10, p. 782-793Article in journal (Refereed) Published
Abstract [en]

The authors have developed a new plastic design method for light-framed timber shear walls, which is capable of analysing the load-bearing capacity of partially anchored shear walls. For proper application of the plastic method it is necessary to ensure ductile behaviour of the sheathing-to-framing joints and to avoid brittle failure of the bottom rail. In a partially anchored shear wall, the tying down forces are developed in the sheathing-to-framing joints along the bottom rail, which may introduce a brittle type of failure of the bottom rail that needs to be eliminated in order for the plastic method to be applicable. This paper deals with design of anchor bolts needed to tie down the bottom rail properly and it describes experimental results for proper design of washers for anchor bolts to avoid these splitting failures of the bottom rail. The effect of different washer sizes and location of the anchor bolts on the failure load when splitting of the bottom rail occurs is presented. The tests indicate that the failure load depends on the distance from the edge of the washer to the loaded edge of the bottom rail. An explicit design equation for the capacity of the bottom rail is presented.

Keywords
design methods & aids, timber structures
National Category
Civil Engineering
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-57609 (URN)10.1680/jstbu.15.00015 (DOI)000384059800006 ()2-s2.0-84986193703 (Scopus ID)
Available from: 2016-10-26 Created: 2016-10-25 Last updated: 2017-11-29Bibliographically approved
Girhammar, U. A. & Källsner, B. (2016). Horizontal Stabilisation of Sheathed Timber Frame Structures Using Plastic Design Methods - Introducing a Handbook Part 1: Design Principles for Horizontal Stabilisation. In: WORLD MULTIDISCIPLINARY CIVIL ENGINEERING-ARCHITECTURE-URBAN PLANNING SYMPOSIUM 2016, WMCAUS 2016: . Paper presented at World Multidisciplinary Civil Engineering-Architecture-Urban Planning Symposium (WMCAUS), JUN 13-17, 2016, Prague, CZECH REPUBLIC (pp. 618-627). Elsevier
Open this publication in new window or tab >>Horizontal Stabilisation of Sheathed Timber Frame Structures Using Plastic Design Methods - Introducing a Handbook Part 1: Design Principles for Horizontal Stabilisation
2016 (English)In: WORLD MULTIDISCIPLINARY CIVIL ENGINEERING-ARCHITECTURE-URBAN PLANNING SYMPOSIUM 2016, WMCAUS 2016, Elsevier, 2016, p. 618-627Conference paper