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Landel, P., Johansson, M. & Linderholt, A. (2021). Comparative study of wind-induced accelerations in tall timber buildings according to four methods. In: WCTE 2021, World Conference on Timber Engineering, Santiago, Chile, 9 - 12 August: . Paper presented at WCTE 2021, World Conference on Timber Engineering, Santiago, Chile, 9 - 12 August. World Conference on Timber Engineering, WCTE
Open this publication in new window or tab >>Comparative study of wind-induced accelerations in tall timber buildings according to four methods
2021 (English)In: WCTE 2021, World Conference on Timber Engineering, Santiago, Chile, 9 - 12 August, World Conference on Timber Engineering, WCTE , 2021Conference paper, Published paper (Refereed)
Abstract [en]

The height and the market share of multi-story timber buildings are both rising. During the last two decades, the Architectural and Engineering Construction industry has developed new reliable solutions to provide strength, structural integrity, fire safety and robustness for timber structures used in the mid- and high-rise sectors.According to long-time survey and lab experiments, motion sickness and sopite syndrome are the main adverse effects on the occupants of a wind sensitive building. For tall timber buildings, wind-induced vibrations seem to be a new critical design aspect at much lower heights than for traditional steel-concrete buildings. To guarantee good comfort, the horizontal accelerations at the top of tall timber buildings must be limited. Two methods in the Eurocode for wind actions (EN1991-1-4), procedure 1 in Annex B (EC-B) and procedure 2 in Annex C (EC-C), provide formulas to estimate the along-wind accelerations. The Swedish code advises to follow a method specified in the National Annex to the Eurocode (EKS) and the American ASCE 7-2016 recommend another method.

This study gives an overview on the background of the different methods for the evaluation of along-wind accelerations for buildings. Estimated accelerations of several tall timber buildings evaluated according to the different methods are compared and discussed. The scatter of the accelerations estimated with different codes is big and increases the design uncertainty of wind induced response at the top of tall timber buildings.

Place, publisher, year, edition, pages
World Conference on Timber Engineering, WCTE, 2021
Keywords
Tall timber buildings, serviceability, wind loads, dynamical response, along-wind peak acceleration, wind-induced vibrations, comfort, building code
National Category
Building Technologies Architectural Engineering
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-106188 (URN)2-s2.0-85120725506 (Scopus ID)
Conference
WCTE 2021, World Conference on Timber Engineering, Santiago, Chile, 9 - 12 August
Funder
Vinnova, 2018-04976Swedish Research Council Formas, 2018-04976Swedish Energy Agency, 2018-04976
Available from: 2021-08-19 Created: 2021-08-19 Last updated: 2023-06-21Bibliographically approved
Landel, P., Linderholt, A. & Johansson, M. (2019). Test-analyses comparisons of a stabilizing glulam truss for a tall building. In: Book of abstracts: CompWood June 17-19, 2019, Växjö, Sweden: International Conference on Computational Methods in Wood Machanics - from Material Properties to Timber Structure. Paper presented at CompWood 2019, June 17-19, Växjö. Linnaeus University
Open this publication in new window or tab >>Test-analyses comparisons of a stabilizing glulam truss for a tall building
2019 (English)In: Book of abstracts: CompWood June 17-19, 2019, Växjö, Sweden: International Conference on Computational Methods in Wood Machanics - from Material Properties to Timber Structure, Linnaeus University , 2019Conference paper, Oral presentation with published abstract (Refereed)
Place, publisher, year, edition, pages
Linnaeus University, 2019
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-85543 (URN)978-91-88898-64-7 (ISBN)
Conference
CompWood 2019, June 17-19, Växjö
Funder
Swedish Research Council Formas, 942-2015-115
Available from: 2019-06-18 Created: 2019-06-18 Last updated: 2023-01-11Bibliographically approved
Landel, P., Linderholt, A. & Johansson, M. (2018). Dynamical properties of a large glulam truss for a tall timber building. In: Presented at the 2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23, 2018: . Paper presented at 2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23, 2018. , Article ID S747.
Open this publication in new window or tab >>Dynamical properties of a large glulam truss for a tall timber building
2018 (English)In: Presented at the 2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23, 2018, 2018, article id S747Conference paper, Published paper (Refereed)
Abstract [en]

When designing a tall timber building, the accelerations due to wind loads are in many cases decisive. The parameters governing the dynamic behaviour of the building are the structure’s stiffness, damping and mass together with the loads. The first two parameters are not well-known during the serviceability limit state of timber structures generally and of timber connections specifically.

In this study, dynamical properties of a large glulam truss, a part of the vertical and horizontal structural system in a residential six-storey timber building, are estimated from measurements made in the manufacturing plant. The timber members of the truss are joined with slotted-in steel plates and dowels. Forced vibrational test data are used to extract the dynamical properties. Finite element (FE) models, supported by the experimental results, were developed and simulations, to study the influence of the connection stiffnesses on the total behaviour, were performed. The vibration test results of measurements made on separate structural parts give valuable input to model timber structures and better possibilities to simulate the dynamic behaviour of tall timber buildings as well as the load distribution in wooden structures in the serviceability limit state.

Keywords
Vibrational testing, experimental modal analysis, stiffness and damping, timber joints, slotted-in steel plates with dowels connection
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering; Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-76789 (URN)2-s2.0-85058173513 (Scopus ID)
Conference
2018 World Conference on Timber Engineering, Seoul, Republic of Korea, August 20-23, 2018
Projects
Tall Timber Buildings – concept studies
Funder
Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, 942-2015-115
Available from: 2018-07-11 Created: 2018-07-11 Last updated: 2022-05-19Bibliographically approved
Ormarsson, S. & Johansson, M. (2018). Finite element simulation of global structural behaviour of multifamily timber buildings using prefabricated volume modules. In: WCTE 2018 - World Conference on Timber Engineering: . Paper presented at WCTE 2018, World Conference on Timber Engineering, August 20-23, 2018, Seoul, South Korea. World Conference on Timber Engineering (WCTE)
Open this publication in new window or tab >>Finite element simulation of global structural behaviour of multifamily timber buildings using prefabricated volume modules
2018 (English)In: WCTE 2018 - World Conference on Timber Engineering, World Conference on Timber Engineering (WCTE) , 2018Conference paper, Published paper (Refereed)
Abstract [en]

The potential of building multi-storey timber buildings has changed in recent decades. The building of apartment houses with fully prefabricated volume modules in wood is an industry sector that is rapidly increasing its capacity. A number of house manufacturers that have delivered volume modules, primarily for single family homes, are now expanding their production to multi-storey buildings up to 6-8 floors. This is a challenging task for producers, since the available design procedures for timber buildings have not yet been fully implemented for these types of buildings.The aim of the work is to develop an efficient and flexible finite element model to analyse the three-dimensional structural behaviour of multi-storey buildings using prefabricated volume modules made by wooden stud-and-rail structure. The model will be used to study the global structural behaviour of various timber walls, volume modulus and modular-based multi-storey buildings when subjected to different types of loading. The model will also be used for detailed analysis and design (using so-called adaptive modelling) of the most critical (weak) parts of the structure.

Place, publisher, year, edition, pages
World Conference on Timber Engineering (WCTE), 2018
Keywords
Wood, multi-storey timber buildings, volume modules, finite element modelling
National Category
Construction Management Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-82135 (URN)2-s2.0-85058174258 (Scopus ID)
Conference
WCTE 2018, World Conference on Timber Engineering, August 20-23, 2018, Seoul, South Korea
Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2020-05-08Bibliographically approved
Hu, M., Briggert, A., Olsson, A., Johansson, M., Oscarsson, J. & Säll, H. (2018). Growth layer and fibre orientation around knots in Norway spruce: a laboratory investigation. Wood Science and Technology, 52(1), 7-27
Open this publication in new window or tab >>Growth layer and fibre orientation around knots in Norway spruce: a laboratory investigation
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2018 (English)In: Wood Science and Technology, ISSN 0043-7719, E-ISSN 1432-5225, Vol. 52, no 1, p. 7-27Article in journal (Refereed) Published
Abstract [en]

The strength of structural timber largely depends on the occurrence of knots and on the local material directions in the surroundings of such knots. There is, however, a lack of methods for establishing a full dataset of the local material directions. The present research aims at the development and application of a laboratory method to assess the geometry of growth layers and the orientation of fibres in a high-resolution 3D grid within wood specimens containing knots. The laboratory method was based on optical flatbed scanning and laser scanning, the former resulting in surface images and the latter, utilizing the tracheid effect, resulting in in-plane fibre angles determined in high-resolution grids on scanned surfaces. A rectangular solid wood specimen containing a single knot was cut from a tree in such a way that it could be assumed that a plane of symmetry existed in the specimen. By splitting the specimen through this plane through the centre line of the knot, two new specimens with assumed identical but mirrored properties were achieved. On one of the new specimens, the longitudinal-radial plane was subsequently scanned, and the longitudinal–tangential plane was scanned on the other. Then, by repeatedly planing off material on both specimens followed by scanning of the new surfaces that gradually appeared, 3D coordinate positions along different growth layers and 3D orientation of fibres in a 3D grid were obtained. Comparisons between detected fibre orientation and growth layer geometry were used for the assessment of the accuracy obtained regarding 3D fibre orientation. It was shown that the suggested method is well suited to capture growth layer surfaces and that it provides reliable information on 3D fibre orientation close to knots. Such knowledge is of great importance for understanding the properties of timber including knots. The quantitative data obtained are also useful for calibration of model parameters of general models on fibre orientation close to knots.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Wood Science
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-69631 (URN)10.1007/s00226-017-0952-3 (DOI)000419587400001 ()2-s2.0-85028777374 (Scopus ID)
Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2020-05-04Bibliographically approved
Hu, M., Olsson, A., Johansson, M. & Oscarsson, J. (2018). Modelling local bending stiffness based on fibre orientation in sawn timber. European Journal of Wood and Wood Products, 76(6), 1605-1621
Open this publication in new window or tab >>Modelling local bending stiffness based on fibre orientation in sawn timber
2018 (English)In: European Journal of Wood and Wood Products, ISSN 0018-3768, E-ISSN 1436-736X, Vol. 76, no 6, p. 1605-1621Article in journal (Refereed) Published
Abstract [en]

Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, has been utilized in a previously developed machine strength grading method, but rather crude assumptions regarding the fibre orientation in the interior of boards and a mechanical model that does not capture the full compliance of knotty sections were adopted. The purpose of the present study was to suggest and verify a model with which local bending stiffness can be predicted with high accuracy. This study included development of a model of fibre orientation in the interior of boards, and application of a three-dimensional finite element model that is able to capture the compliance of the board. Verification included bending of boards in the laboratory and application of digital image correlation to obtain strain fields comparable to those obtained by finite element simulation. Results presented comprise strain fields of boards subjected to bending and calculated bending stiffness profiles along boards. Comparisons of results indicated that the model suggested here was sufficient to capture the variation of local bending stiffness along boards with very high accuracy.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Wood Science
Research subject
Technology (byts ev till Engineering), Civil engineering; Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-69634 (URN)10.1007/s00107-018-1348-2 (DOI)000447204700004 ()2-s2.0-85053440591 (Scopus ID)
Available from: 2018-01-09 Created: 2018-01-09 Last updated: 2019-10-24Bibliographically approved
Hu, M., Olsson, A., Johansson, M. & Oscarsson, J. (2018). Modelling local bending stiffness of Norway spruce sawn timber using scanned fibre orientation. In: Proceedings, 2018, ICEM 2018: The 18th International Conference on Experimental Mechanics (ICEM 2018); Brussels, Belgium 1–5 July 2018. Paper presented at ICEM18, the eighteenth International Conference of experimental Mechanics, Brussels, Belgium, 1–5 July 2018. MDPI
Open this publication in new window or tab >>Modelling local bending stiffness of Norway spruce sawn timber using scanned fibre orientation
2018 (English)In: Proceedings, 2018, ICEM 2018: The 18th International Conference on Experimental Mechanics (ICEM 2018); Brussels, Belgium 1–5 July 2018, MDPI, 2018Conference paper, Published paper (Refereed)
Abstract [en]

Strength of structural timber depends to a high degree on the occurrence of knots and on the local fibre deviation around such defects. Knowledge of local fibre orientation, obtained by laser scanning, have been utilized in a previously developed machine strength grading method. However, that method was based on rather crude assumptions regarding the fibre orientation in the interior of boards and a mechanical model that does not capture the full compliance of knotty sections. The purpose of the present study was to suggest and verify a model by which local bending stiffness can be predicted with high accuracy. This study included development of a model of fibre orientation in the interior of boards, and application of a three-dimensional finite element model that is able to capture the compliance of the board. Verification included bending of boards in laboratory and application of digital image correlation to obtain strain fields comparable to those obtained by finite element simulation. Results presented comprise strain fields of boards subjected to bending and calculated bending stiffness variation along boards. Comparisons of results indicated that models suggested herein were sufficient to capture the variation of local bending stiffness along boards with very high accuracy.

Place, publisher, year, edition, pages
MDPI, 2018
Series
Proceedings, E-ISSN 2504-3900 ; 2018:2(8)
National Category
Wood Science
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-113194 (URN)10.3390/ICEM18-05426 (DOI)
Conference
ICEM18, the eighteenth International Conference of experimental Mechanics, Brussels, Belgium, 1–5 July 2018
Available from: 2022-06-01 Created: 2022-06-01 Last updated: 2023-10-10Bibliographically approved
Hallingbäck, H. R., Högberg, K.-A., Säll, H., Lindeberg, J., Johansson, M. & Jansson, G. (2018). Optimal timing of early genetic selection for sawn timber traits in Picea abies. European Journal of Forest Research, 137(4), 553-564
Open this publication in new window or tab >>Optimal timing of early genetic selection for sawn timber traits in Picea abies
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2018 (English)In: European Journal of Forest Research, ISSN 1612-4669, E-ISSN 1612-4677, Vol. 137, no 4, p. 553-564Article in journal (Refereed) Published
Abstract [en]

In breeding Norway spruce, selection for improved growth and survival is performed at age 10-15 years in order to optimize genetic gain per year. We investigated whether a selection based on wood traits such as density and grain angle, measured under bark in the field at the same age would be informative enough with respect to structural quality traits of sawn boards. To achieve this objective, a sawing study was conducted on the butt logs of 401 trees from a 34-year-old Norway spruce progeny trial situated in southern Sweden. Stem discs were excised from the top of the logs and radial profile data of grain angle, and wood density was recorded for specific annual rings. The sawn and dried boards were assessed for structural traits such as twist, board density, bending stiffness (static modulus of elasticity, sMoE) and bending strength (modulus of rupture, MoR). Additive genetic correlations (r (a)) between single annual ring density measurements and board density, sMoE and MoR were consistently strong (r (a)> 0.7) for annual rings 5-13. Genetic correlations of similar magnitude between grain angle and board twist were estimated for all investigated annual rings (from 2 to around 26 under bark). Consequently, it was found that indirect selection for wood density and grain angle at the tree age 10-16 years would result in more genetic gain per year than selection at later ages. This makes it feasible to perform simultaneous selection of progeny in the field for both growth and wood traits at similar ages.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Early selection, Grain angle, Wood density, Sawmill study, Structural quality traits, Quantitative genetics
National Category
Wood Science
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-77386 (URN)10.1007/s10342-018-1123-2 (DOI)000439337000012 ()2-s2.0-85048553040 (Scopus ID)
Available from: 2018-08-30 Created: 2018-08-30 Last updated: 2020-10-26Bibliographically approved
Hu, M., Olsson, A., Johansson, M., Oscarsson, J. & Serrano, E. (2016). Assessment of a Three-Dimensional Fiber Orientation Model for Timber. Wood and Fiber Science, 48(4), 271-290
Open this publication in new window or tab >>Assessment of a Three-Dimensional Fiber Orientation Model for Timber
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2016 (English)In: Wood and Fiber Science, ISSN 0735-6161, Vol. 48, no 4, p. 271-290Article in journal (Refereed) Published
Abstract [en]

Wood is an orthotropic material with very different properties along and across fibers, and every board has its own pattern of knots and fiber deviations. Therefore, detailed knowledge of the three-dimensional (3D) fiber orientation of individual boards would enable more accurate assessment of properties such as stiffness, strength, and shape stability. This paper presents a method for modeling 3D fiber orientation of side boards of Norway spruce. The method is based on dot laser scanning and utilization of the tracheid effect, and it is verified by a comparison between strain fields calculated on the basis of the fiber orientation model and corresponding strains determined using digital image correlation (DIC) technique. By means of the method, it is possible to identify knots and to reproduce the fiber orientation in clear wood in the vicinity of knots. Fiber orientation models of side boards including traversing edge knots were established and integrated in finite element models of boards used for simulation of four-point bending tests. The same boards were also tested in laboratory and displacement fields of the wide faces were recorded at different load levels using DIC technique. Comparisons of strain fields from measurements and simulations showed close agreement, regarding both strain patterns and strain levels. Local strain concentrations caused by very small defects were detected using the models and also found from the laboratory test results. The modeling approach may be used both to achieve improved accuracy of existing machine strength grading methods and, after further development, also for more advanced analysis of eg crack propagation and strength of timber.

National Category
Wood Science
Research subject
Technology (byts ev till Engineering), Forestry and Wood Technology
Identifiers
urn:nbn:se:lnu:diva-57467 (URN)000388430500006 ()2-s2.0-85053473315 (Scopus ID)
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2023-09-22Bibliographically approved
Serrano, E. & Johansson, M. (2016). Förband och anslutningsdetaljer (1ed.). In: Limträhandbok: Del 2. Projektering av limträkonstruktioner (pp. 198-227). Stockholm: Svenskt Trä
Open this publication in new window or tab >>Förband och anslutningsdetaljer
2016 (Swedish)In: Limträhandbok: Del 2. Projektering av limträkonstruktioner, Stockholm: Svenskt Trä , 2016, 1, p. 198-227Chapter in book (Other academic)
Place, publisher, year, edition, pages
Stockholm: Svenskt Trä, 2016 Edition: 1
National Category
Building Technologies
Research subject
Technology (byts ev till Engineering), Civil engineering
Identifiers
urn:nbn:se:lnu:diva-60994 (URN)978-91-980304-6-4 (ISBN)
Available from: 2017-02-27 Created: 2017-02-27 Last updated: 2018-05-17Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5319-4855

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