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Publications (10 of 17) Show all publications
Abrahamsen, R., Johansson, M. & Tulebekova, S. (2023). DYNAMIC RESPONSE OF TALL TIMBER BUILDINGS UNDER SERVICE LOAD – RESULTS FROM THE DYNATTB RESEARCH PROGRAM. In: : . Paper presented at World Conference of Timber Engineering. Oslo, Norway. 2023.
Open this publication in new window or tab >>DYNAMIC RESPONSE OF TALL TIMBER BUILDINGS UNDER SERVICE LOAD – RESULTS FROM THE DYNATTB RESEARCH PROGRAM
2023 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Wind-induced dynamic excitation is a governing design action determining size and shape of modern Tall Timber Buildings (TTBs). The wind actions generate dynamic loading, causing discomfort or annoyance for occupants due to the perceived horizontal sway, i.e. vibration serviceability problem. Although some TTBs have been instrumented and measured to estimate their key dynamic properties (eigenfrequencies, mode shapes and damping), no systematic evaluation of dynamic performance pertinent to wind loading had been performed for the new and evolving construction technologies used in TTBs. The DynaTTB project, funded by the ForestValue research program, mixed on site measurements on existing buildings excited by mass inertia shakers (forced vibration) and/or the wind loads (ambient vibration), for identification of the structural system, with laboratory identification of building elements mechanical features, coupled with numerical modelling of timber structures. The goal is to identify and quantify the causes of vibration energy dissipation in modern TTBs and provide key elements to finite element models. This paper presents an overview of the results of the project and the proposed Guidelines for design of TTBs in relation to their dynamic properties.

Keywords
Timber building, wind load, forced vibration, discomfort, modelling, damping, full scale
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-64170 (URN)
Conference
World Conference of Timber Engineering. Oslo, Norway. 2023
Available from: 2023-03-07 Created: 2023-03-07 Last updated: 2023-06-26Bibliographically approved
Blomqvist, L., Crocetti, R., Claesson, A., Ben Osmane, Z., Ziethén, R. & Johansson, M. (2023). EXPERIMENTAL AND NUMERICAL ANALYSES OF A CONNECTION FOR CLT STRUCTURES. In: Proceedings of the 2023 World Conference on Timber Engineering (WCTE): . Paper presented at World Conference on Timber Engineering (WCTE) (pp. 1154-1159). Oslo, Norway
Open this publication in new window or tab >>EXPERIMENTAL AND NUMERICAL ANALYSES OF A CONNECTION FOR CLT STRUCTURES
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2023 (English)In: Proceedings of the 2023 World Conference on Timber Engineering (WCTE), Oslo, Norway, 2023, p. 1154-1159Conference paper, Published paper (Refereed)
Abstract [en]

Although building systems made of cross-laminated timber (CLT) have become common in Sweden in the past 20 years and they have developed rapidly during the same period, steps remain to be taken to simplify the assembly of such systems, especially at construction sites. Current construction methods, however, remain labour-intensive and thus show room for improvement.

This paper describes a novel connection for the assembly of building elements made of CLT. Simple and inexpensive, the connection is fairly insensitive to manufacturing tolerances and enables rapid, more efficient construction than the connections for CLT structures currently used. Test results show the excellent strength and stiffness of the connection, which also allows the replacement of numerous fasteners, including nails and screws, with only a single steel rod. 

Place, publisher, year, edition, pages
Oslo, Norway: , 2023
Keywords
assembly, connections, cross-laminated timber
National Category
Building Technologies Wood Science
Identifiers
urn:nbn:se:ri:diva-65515 (URN)10.52202/069179-0158 (DOI)
Conference
World Conference on Timber Engineering (WCTE)
Funder
The Kamprad Family Foundation, 20200013
Note

Funding: Familjen Kamprads stiftelse 2020013

Available from: 2023-06-14 Created: 2023-06-14 Last updated: 2023-06-19Bibliographically approved
Linderholt, A., Landel, P. & Johansson, M. (2023). FORCED RESPONSE MEASUREMENTS ON A SEVEN STOREY TIMBER BUILDING IN SWEDEN. In: : . Paper presented at World Conference on Timber Engineering. 2023. Oslo, Norway..
Open this publication in new window or tab >>FORCED RESPONSE MEASUREMENTS ON A SEVEN STOREY TIMBER BUILDING IN SWEDEN
2023 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Forced vibration tests have been conducted on the seven-storey timber building Eken in Mariestad in Sweden. The main objective is to estimate the building’s dynamic properties from test data. The eigenfrequencies, mode shapes and their scaling are useful to calibrate numerical models. However, the most important outcomes are the estimates of the modal damping values. The reason is that the damping impacts the acceleration, and thus the serviceability of the building, and at the same time, it is very hard to model damping. So, during the design phase, one must rely on previous test data (of which very few exist for taller timber buildings) or rule of thumbs. It is therefore important to gain knowledge about the damping for timber buildings in order to enable good designs of future and taller timber buildings. The test data shows that the modal damping is roughly equal to 2% of the critical viscous ones for the eigenmodes extracted. The test campaign on Eken is made as a part of the project Dyna-TTB in which vibrational tests have been performed on eight high-rise timber buildings, in Europe, of which Eken is one.

Keywords
Forced vibration, timber building, damping, eigenmodes, experimental modal analysis, Dyna-TTB
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-64166 (URN)
Conference
World Conference on Timber Engineering. 2023. Oslo, Norway.
Available from: 2023-03-06 Created: 2023-03-06 Last updated: 2023-06-26Bibliographically approved
Vessby, J., Forsberg, T., Johansson, M. & Maharjan, R. (2023). LOAD LEVELS AND CRITICAL DESIGN ISSUES IN A MULTI-STOREY RESIDENTIAL TIMBER BUILDING BUILT UP BY PREFABRICATED VOLUMETRIC ELEMENTS. In: : . Paper presented at World Conference on Timber Engineering (WCTE 2023). 19-22 June 2023, Oslo, Norway. (pp. 4439-4446).
Open this publication in new window or tab >>LOAD LEVELS AND CRITICAL DESIGN ISSUES IN A MULTI-STOREY RESIDENTIAL TIMBER BUILDING BUILT UP BY PREFABRICATED VOLUMETRIC ELEMENTS
2023 (Swedish)Conference paper, Published paper (Refereed)
Abstract [en]

The use of structural timber in residential buildings has increased considerably in Sweden during the last decade. Concomitantly, there has been an emphasis on augmenting the level of prefabrication for such structures. A simultaneous need for education imparted in universities exists, and this paper contributes to this need by outlining a design example of a residential timber building with simple geometry using prefabricated volumetric elements. The serviceability limit state as well as the ultimate limit state have been defined and studied for some critical design situations. The results indicate, for example, that the degree of utilisation in the studied building system for compression perpendicular to the bottom rail in the first storey and buckling of the studs are in the same range - 91 % to 97 % - for the walls separating apartments.

Keywords
Design, Education, Prefabrication, Volumetric structure, Module
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-65552 (URN)10.52202/069179-0578 (DOI)
Conference
World Conference on Timber Engineering (WCTE 2023). 19-22 June 2023, Oslo, Norway.
Available from: 2023-06-27 Created: 2023-06-27 Last updated: 2023-06-27Bibliographically approved
Lemke, U., Johansson, M., Ziethén, R. & Briggert, A. (2023). NEW CRITERIA FOR VISUAL STRENGTH GRADING OF SAWN TIMBER FROM BIRCH GROWN IN SWEDEN. In: : . Paper presented at World Conference on Timber Engineering (WCTE 2023). 19-22 June 2023, Oslo, Norway. (pp. 740-749).
Open this publication in new window or tab >>NEW CRITERIA FOR VISUAL STRENGTH GRADING OF SAWN TIMBER FROM BIRCH GROWN IN SWEDEN
2023 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Today there is no standard for strength grading and CE-marking sawn timber of Birch grown in Sweden, which makes it impossible to use this material as structural timber. Internationally, there are standards for visual grading of hardwood in several European countries. However, these standards may not be used to classify Birch timber grown in Sweden without having been tested and verified to meet the standard's requirements. In a project (BizWOOD) run by RISE, 600 pieces of sawn birch wood from Sweden is visually graded and strength tested. The project aims to result in grading rules for birch, either by using international standards or where international standards will be used as references for the identification of defects that will be included in the grading model. This paper summarizes parts of the BizWOOD project and includes 1) description of sampling and timber origin, 2) visual grading according to international standards, 3) strength testing of the material, 4) evaluation of mechanical characteristics, 5) evaluation of grading techniques.

Keywords
Birch (Betula spp.), density, bending strength, modulus of elasticity, MOR, MOE, strength grading.
National Category
Wood Science
Identifiers
urn:nbn:se:ri:diva-65551 (URN)10.52202/069179-0102 (DOI)
Conference
World Conference on Timber Engineering (WCTE 2023). 19-22 June 2023, Oslo, Norway.
Available from: 2023-06-27 Created: 2023-06-27 Last updated: 2023-11-01Bibliographically approved
Johansson, M., Blomqvist, L., Norén, J. & Olsson, J. (2023). Prefabricerade ytterväggselement för KL-trästommar.
Open this publication in new window or tab >>Prefabricerade ytterväggselement för KL-trästommar
2023 (Swedish)Report (Other academic)
Abstract [en]

Prefabricated external wall elements for CLT systems

This is a first pre-study to how building with cross-laminated timber (CLT) as a frame system in buildings could be made more efficient using prefabricated exterior wall elements as frame completion for CLT buildings. In carrying out this study, CLT building in Sweden as a rule involves an efficient frame erection of the CLT elements, but with a relatively slow phase to assemble the exterior frame completion. External frame completion of CLT buildings is usually carried out on construction scaffolding, where the layers of insulation and surface layer are built up on site. Prefabrication of the outer layers of the CLT frame that is lifted into place has the potential to save a lot of labor time and thus costs. The report presents requirements and practical aspects that must be taken into account in order for prefabricated exterior wall elements to be feasible in terms of requirements and in practice. The purpose of the report has also been to give tips, inspiration and ideas to consider when producing prefabricated exterior wall elements. In the study, an example solution has been developed with the aim of being wood based to as high degree as possible. The result shows that with relatively simple means it is possible to build a prefabricated wall element that meets established requirements. It is desirable that the outer wall elements are hung in place with the minimum possible finishing work on the facade. When it comes to the division of external wall elements, it is practical to follow a similar division and measurements as for the CLT boards to facilitate handling, assembly and lifting. It should be avoided to have sockets (window panes, door holes and the like) that are broken in its interface between the external wall elements to facilitate uniformity in the dimensioning of the elements. The study shows that it is realistic to create prefabricated exterior wall elements for CLT frames.

Publisher
p. 40
Series
RISE Rapport ; 2023:77
Keywords
CLT, Construction, Prefabrication, Facade
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-65747 (URN)978-91-89821-47-7 (ISBN)
Note

Projektet har finansierats via Södra skogsägarnas Stiftelse för Forskning, Utveckling och Utbildning, Dnr 2020–161. 

Available from: 2023-08-07 Created: 2023-08-07 Last updated: 2023-08-07Bibliographically approved
Linderholt, A., Johansson, M. & Landel, P. (2023). Tall Timber Buildings Subjected to Wind Loads - Full Scale Experimental Dynamics. In: Wood Building Nordic: . Paper presented at Wood Building Nordic.
Open this publication in new window or tab >>Tall Timber Buildings Subjected to Wind Loads - Full Scale Experimental Dynamics
2023 (English)In: Wood Building Nordic, 2023Conference paper, Published paper (Other academic)
Abstract [en]

Wind-induced dynamic excitation is a governing design action determining size and shape of modern Tall Timber Buildings (TTBs). The wind actions generate dynamic loading, causing discomfort or annoyance for occupants due to the perceived horizontal sway, i.e. a vibration serviceability problem. The DynaTTB project, funded by the ForestValue research program, mixed on-site measurements on timber buildings, for identification of the structural system, with numerical modelling of timber structures. The goal was to identify and quantify the causes of vibration energy dissipation in modern TTBs and provide key elements to finite element models. This paper presents an overview of the project.    The paper also presents measurements using forced vibration conducted on the seven-storey timber building Eken in Mariestad in Sweden. The main objective is to estimate the building’s dynamic properties from test data. The eigenfrequencies, mode shapes and their scalings are useful to calibrate numerical models. However, the most important outcomes are the estimates of the modal damping values. The test data shows that the modal damping is roughly equal to 2% of the critical viscous ones for the eigenmodes extracted.

Keywords
Dynamics, wind load, forced response, Dyna-TTB
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-67494 (URN)
Conference
Wood Building Nordic
Funder
Vinnova
Available from: 2023-10-04 Created: 2023-10-04 Last updated: 2023-10-05Bibliographically approved
Landel, P., Johansson, M. & Linderholt, A. (2021). Comparative study of wind-induced accelerations in tall timber buildings according to four methods. In: World Conference on Timber Engineering 2021, WCTE 2021: . Paper presented at World Conference on Timber Engineering 2021, WCTE 2021, 9 August 2021 through 12 August 2021. 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: World Conference on Timber Engineering 2021, WCTE 2021, 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
Along-wind peak acceleration, Building code, Comfort, Dynamical response, Serviceability, Tall timber buildings, Wind loads, Wind-induced vibrations, Accident prevention, Codes (standards), Competition, Construction industry, Housing, Timber, Uncertainty analysis, Vibrations (mechanical), Comparatives studies, Eurocodes, Peak acceleration, Wind induced vibrations, Wind load, Wind-induced acceleration, Acceleration
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-57965 (URN)2-s2.0-85120725506 (Scopus ID)
Conference
World Conference on Timber Engineering 2021, WCTE 2021, 9 August 2021 through 12 August 2021
Note

Funding text 1: The research leading to these results has received funding from the ForestValue Research Programme which is a transnational research, development and innovation programme jointly funded by national funding organisations within the framework of the ERA-NET Cofund ‘ForestValue – Innovating forest-based bioeconomy.

Available from: 2022-01-12 Created: 2022-01-12 Last updated: 2023-06-07Bibliographically approved
Ormarsson, S., Vessby, J. & Johansson, M. (2021). Design of innovative modular-based timber structure based on advanced modeling and full-scale tests. In: World Conference on Timber Engineering 2021, WCTE 2021: . Paper presented at World Conference on Timber Engineering 2021, WCTE 2021, 9 August 2021 through 12 August 2021. World Conference on Timber Engineering (WCTE)
Open this publication in new window or tab >>Design of innovative modular-based timber structure based on advanced modeling and full-scale tests
2021 (English)In: World Conference on Timber Engineering 2021, WCTE 2021, World Conference on Timber Engineering (WCTE) , 2021Conference paper, Published paper (Refereed)
Abstract [en]

The building of low and mid-rise modular-based timber buildings is a growing industry sector worldwide. Today, the use of prefabricated light-frame volume modules (sometimes with CLT walls) is a prevalent and innovative construction method. This building method has many advantages, though some of the technical solutions and design methods are quite challenging and should be optimised without risking structural safety. The paper presents results from an ongoing research project that deals with testing and numerical analysis of light-frame timber test modules. It focuses on the testing and simulation of global racking stiffness of different types of test modules and the testing of a friction-based joint between two test modules. The modules showed larger shear load carrying capacity than expected. They also showed a ductile failure behaviour and large variation in racking stiffness between different types of test modules. 

Place, publisher, year, edition, pages
World Conference on Timber Engineering (WCTE), 2021
Keywords
FE-simulations, Light-frame timber modules, Modular-based timber buildings, Racking tests of modules, Architectural design, Stiffness, Testing, Wooden buildings, Fe simulation, Light frames, Light-frame timber module, Modular-based timber building, Modulars, Racking test of module, Racking tests, Test modules, Timber buildings, Timber structures, Timber
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-57961 (URN)2-s2.0-85120751254 (Scopus ID)
Conference
World Conference on Timber Engineering 2021, WCTE 2021, 9 August 2021 through 12 August 2021
Available from: 2022-01-10 Created: 2022-01-10 Last updated: 2023-05-25Bibliographically approved
Blomqvist, L., Honfi, D., Johansson, M., Ziethén, R., Crocetti, R. & Norén, J. (2021). DEVELOPMENT OF NOVEL STRUCTURAL CONNECTIONS –INSPIRATION FROM FURNITURE INDUSTRY. In: World Conference onTimber Engineering (WCTE) 2021: . Paper presented at World Conference onTimber Engineering (WCTE) 2021. Santiago, Chile
Open this publication in new window or tab >>DEVELOPMENT OF NOVEL STRUCTURAL CONNECTIONS –INSPIRATION FROM FURNITURE INDUSTRY
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2021 (English)In: World Conference onTimber Engineering (WCTE) 2021, Santiago, Chile, 2021Conference paper, Published paper (Refereed)
Abstract [en]

The presented project aims to develop prototypes for building connections inspired by the furniture and interior industry and explore them with representatives from the timber construction industry. The long-term vision is that actors from furniture and building industry together develop a smart system for assembly of building elements, which provide higher precision, faster and more efficient assembly than what is available today. The prototype connectiondeveloped in this project shows that the idea is ripe for full-scale investigation. Laboratory tests showed promising results due to the high failure loads obtained with very high stiffness.

Place, publisher, year, edition, pages
Santiago, Chile: , 2021
Keywords
assembly, connections, CLT
National Category
Wood Science Building Technologies
Identifiers
urn:nbn:se:ri:diva-55834 (URN)
Conference
World Conference onTimber Engineering (WCTE) 2021
Projects
Montageförband på byggarbetsplatsen (Assembly connections on the construction site)
Funder
Vinnova, 2018-04332The Kamprad Family Foundation, 20200013
Available from: 2021-08-12 Created: 2021-08-12 Last updated: 2023-05-25Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5319-4855

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