| 1. |
- Abrahamsen, Rune, et al.
(författare)
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Dynamic response of tall timber buildings under service load : results from the dynattb research program
- 2023
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Ingår i: World Conference on Timber Engineering 2023 (WCTE 2023). - : Curran Associates, Inc.. - 9781713873297 ; , s. 2907-2914
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 2. |
- Ahn, Namhyuck, et al.
(författare)
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Envisioning mass timber buildings for circularity : life cycle assessment of a mass timber building with different end-of-life (EoL) and post-EoL options
- 2023
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Ingår i: WCTE 2023-World Conference on Timber Engineering. - : Curran Associates, Inc.. - 9781713873297 ; , s. 3581-3587
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Konferensbidrag (refereegranskat)abstract
- The foundation of the circular economy in the construction sector is based on implementing the deconstruction and reuse of buildings, providing the potential for a closed loop of building materials within the supply chain. Mass timber buildings using large, prefabricated elements and certain types of reversible mechanical connections are deemed to have great potential for post end-of-life (EoL) options, including recycling and reuse. To fully characterize the benefits of reusing post-use mass timber in new construction projects, it is crucial to conceptualize a ‘grave-to-gate’ approach, including the complete analysis of post-EoL activities and impacts on the material’s second life. In this study, a comparative life cycle assessment (LCA) including different EoL and post-EoL options for a virtual reference mid-rise mass timber building in the Pacific Northwest (PNW) of the United States was conducted. Among four different deconstruction and reuse scenarios examined in this study, a case of nearly complete reconstruction of a mass timber building for the second service life used as an idealized reference established an optimistic limit for reduction of global warming potential (GWP) by 13-41% compared to the ‘demolish and landfill’ decision, depending on the scenario. The demolition and landfill scenario had the lowest net impact since the GWMP calculations accounted for the carbon storage benefits in the landfill in addition to the carbon stored in the building.
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| 3. |
- Alen, Malagic, et al.
(författare)
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Reinforced notched cross-laminated timber plates : Load-bearing capacity and methodology for predicting the force in reinforcement
- 2023
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Ingår i: Proceedings from the 13th World Conference on Timber Engineering (2023). - 9781713873273 - 9781713873297 ; , s. 2442-2453
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the estimation of the design force in self-tapping screws used as a reinforcement ofnotched cross laminated timber plates (CLT). With the reinforcement, apart from an increased load-carrying capacity, amore ductile behaviour of this detail can be achieved. An analytical model based on the Timoshenko Beam Theory wasdeveloped, enabling the estimation of the axial force in the reinforcement. A parametric numerical analysis was conductedto verify the model and to provide possible ways for the calibration. The results show a good matching of the model withthe numerical results. The load-bearing capacity is analysed using a simple fracture mechanics model taking intoconsideration the effect of the reinforcement to correctly depict the increase in performance. Theoretical and numericalresults are compared with experimental findings and show acceptable correlations encouraging a further development anda subsequent implementation in EN 1995-1-1.
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| 4. |
- Aquino, Caroline, et al.
(författare)
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Influence of Test Methods on the Parallel to Grain Embedment Strength and Foundation Modulus Characterization
- 2023
-
Ingår i: Proceedings from the 13th World Conference on Timber Engineering 2023. - Oslo, Norway : World Conference on Timber Engineering (WCTE). - 9781713873297 - 9781713873273 ; , s. 3667-3674
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Konferensbidrag (refereegranskat)abstract
- Different test setups have been reported in the literature for the determination of the embedment strengthin timber elements. These variances hinder a straightforward comparison between available test data. It is difficult todetermine if the source of variability lies in intrinsic timber properties or is related to the test protocol used. This paperaims to provide a better insight into the influence of embedment strength test methods, comparing experimental resultsfrom different test setups within the guidelines of EN 383 and ASTM D 5764-97a for Scots pine wood (Pinus sylvestris)and Spruce (Picea Abies). A robust statistical analysis was performed to identify statistically significant differencesbetween the groups evaluated. The analysis of the parallel to grain embedment strength showed that the results differedbetween standards, pointing out the potential bias inserted in the embedment properties given their evaluation method.Moreover, the thickness of the specimen tests also proved to influence the yield and ultimate embedment strength for thewood species tested.
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| 5. |
- Azinović, Boris, et al.
(författare)
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INNOCROSSLAM : Adding knowledge towards increased use of cross laminated timber (CLT)
- 2023
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Ingår i: Proceedings from the 13th World Conference on Timber Engineering (2023). - 9781713873273 - 9781713873297 ; , s. 2432-2441
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Konferensbidrag (refereegranskat)abstract
- The research project Innovative Solutions for Cross Laminated Timber Structures (InnoCrossLam) wasrecently finished. The project aimed at increasing the competitiveness of CLT as a versatile engineered product, byincreasing its predictability in demanding design situations not covered by the guidelines of today, or standards and codesforeseeable in the near future (e.g., second generation of European design standards). This paper summarises the mainproject findings in the context of innovative CLT structures, such as: i. contemporary design approaches ii. the use of(non)linear FE modelling iii. experimental investigation of complex details for CLT structures, iv. investigation ofmultifunctional CLT. In this paper, the motivation behind the research topics within the project InnoCrossLam isexplained and backed-up by exemplary results and discussion on future work.
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| 6. |
- Dagenais, Christian, et al.
(författare)
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Fire Safe Use of Wood in Buildings : Global Design Guide
- 2023
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Ingår i: World Conference on Timber Engineering. - : World Conference on Timber Engineering (WCTE). - 9781713873297 ; , s. 4627-4635
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Konferensbidrag (refereegranskat)abstract
- Building codes around the globe dictate the design and construction of buildings. For most buildings, designers will follow prescriptive code provisions to demonstrate code compliance. However, some buidling codes allow the use of performance-based design to demonstrate code compliance. Performance-based design is usually more complex but allows for greater flexibility in the use of materials and systems. Regardless of the code compliance methods, the combustibility of timber structures and wood products needs to be well understood and properly accounted for in building designs. This paper describes the develpment of a new international guidance document on fire safety in timber building within the Fire Safe Use of Wood (FSUW) network, written by 13 lead authors assisted by more than 20 experts in over a dozen different countries.
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| 7. |
- Gikonyo, Joan, et al.
(författare)
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Numerical Modelling of a Cross-Laminated Timber-to-Concrete Dowel-Type Connection Using the Beam-on-Foundation Model
- 2023
-
Ingår i: Proceedings from the 13th World Conference on Timber Engineering 2023. - Oslo, Norway : World Conference on Timber Engineering (WCTE). - 9781713873297 - 9781713873273 ; , s. 3101-3110
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Konferensbidrag (refereegranskat)abstract
- The aim of the research presented herein is to investigate the mechanical behaviour of cross-laminated timber (CLT)-to-concrete dowel-type connections. For reliable timber-concrete-composite structures, mechanical connections between the two construction materials are of great importance. This paper investigates the nonlinear load-displacement behaviour, giving access to the stiffness and strength, as well as ductile connection failure modes, of a CLT-to-concrete composite connection using a Beam-on-Foundation (BoF) model. The latter is a numerical model that utilizes non-linear springs for the interaction between the fastener and the surrounding CLT and concrete materials. The influence of: (i) fastener diameter, (ii) initial slip, (iii) concrete embedment properties, and (iv) axial fastener resistance due to friction, on the connection shear capacity and slip modulus, was investigated in a parameter study. The nonlinear load-displacement response, connection stiffness and strength predicted by the BoF model were moreover compared to laboratory tests and the European Yield Model (EYM), which supported the validity of the BoF model. In addition, it was shown that the BoF model could enhance the prediction of the slip modulus compared to the current design regulations in Eurocode 5.
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| 8. |
- Huber, Johannes Albert Josef, 1989-, et al.
(författare)
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Evaluation of Models Of Fibre Orientation in Sawn Timber Using Synchronised Computed Tomography and Optical Scanning Data
- 2023
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Ingår i: World Conference on Timber Engineering (WCTE 2023). - : World Conference on Timber Engineering 2023 (WCTE 2023). ; , s. 421-427, s. 421-427
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Konferensbidrag (refereegranskat)abstract
- Optical scanning and X-ray computed tomography (CT) scanning of sawn timber provide a large number of data points, on which data-driven numerical models can be based for simulations. These models require information about the deviations of the fibre orientations in the vicinity of knots. Optical scanning can be used to measure the in-plane fibre orientation on wood surfaces. In CT scans of sawn timber, the fibre orientation around knots can be estimated using a new fibre reconstruction algorithm based on the density gradient. The goal of this paper is to compare and synchronise optical and CT scanning data of sawn timber and then use the combined data set to evaluate fibre orientations derived from both representations. The material comprised sawn timber of Norway spruce, in which alignment holes were drilled. The timber was scanned in an industrial CT scanner and subsequently in an industrial optical scanner where scanning was repeated after successive planing of the sawn timber surface. The results show that a projective mapping in combination with a spline interpolation are required for synchronisation, and that the in-plane fibre orientations calculated from the density gradients are qualitatively similar to the orientations derived from the optical data.
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| 9. |
- Kržan, Meta, et al.
(författare)
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Protocols and Results Analysis Methods for Cyclic Tests of Timber Joints : A Discussion
- 2023
-
Ingår i: Proceedings from the 13th World Conference on Timber Engineering 2023. - Oslo, Norway : World Conference on Timber Engineering (WCTE). - 9781713873297 - 9781713873273 ; , s. 3685-3693
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Konferensbidrag (refereegranskat)abstract
- Current testing procedures for cyclic loading are quite flexible and the influence of fundamental testing parameters on the obtained load-deformation behaviour is often questioned (number and amplitude of the loading cycles, loading rate, number of specimens, etc.). On the other hand, different methods for data assessment have been used for the definition of stiffness, ductility, strength and stiffness degradation, as well as parameters for analytical and numerical models. However, reliable and well-established assessment methods are required, to support the safe and economic design of timber joints. Fundamental parameters for seismic design, such as ductility or strength degradation, cannot depend on the testing protocol and method for assessment of the data results. In this context, it is important to compare the most representative loading protocols, and assessment methods of the test results, through detailed analysis and discussion. Different types of timber connections, made of distinct materials and tested in different laboratories, must be evaluated. This work will be developed within the RILEM TC TPT, and this paper represents a first contribution to a needed discussion about the testing protocols to evaluate timber connections. In the end, it is expected to present proposals on how to characterize better the properties and behaviour of timber connections under cyclic loading and how to fully utilize their potential in design.
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| 10. |
- Larsson, Carl, et al.
(författare)
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A Survey of the design of timber-concrete hybrid buildings in Sweden
- 2023
-
Ingår i: World Conference on Timber Engineering (WCTE 2023), 19-22 June, Oslo. - Oslo : World Conference on Timber Engineering (WCTE). - 9781713873297 ; , s. 4338-4344
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Konferensbidrag (refereegranskat)abstract
- There is a growing interest in timber buildings in Sweden and increased availability of Glulam (GLT) andparticularly Cross Laminated Timber (CLT) products. Timber buildings, though, often have difficulties in fulfilling theperformance requirements of a building project. The use of concrete elements in addition to timber elements in the load-bearing structure is a widespread solution, introducing timber-concrete hybrid buildings. The study presents responsesfrom interviews regarding ten different timber-concrete hybrid building projects in Sweden with a load-bearing structureabove the foundation level in both timber and concrete. Four main types of timber-concrete hybrids were found: a CLTstructure on top of a concrete structure, a post-beam system in GLT with CLT slabs and concrete walls, a post-beamsystem in GLT with concrete hollow core slabs, and a timber structure with some slabs in concrete. The results show thattimber-concrete hybrid buildings are flexible and suitable for various construction types. The reasons for using concretein timber construction were primarily to increase self-weight, obtain longer span lengths, and overcome shear wallcapacity issues. There is still a lack of competence in the design of structural timber projects, and at most, five differentstructural designers were involved in the load-bearing design of a single building. This highlights issues regarding projectmanagement of the design process within timber-concrete hybrid buildings
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| 11. |
- Linderholt, Andreas, 1968-, et al.
(författare)
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Forced response measurements on a seven storey timberbuilding in Sweden
- 2023
-
Ingår i: World Conferenceon TimberEngineering WCTE 2023. - : Curran Associates, Inc.. - 9781713873297 - 9781713873273 ; , s. 2877-2884
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Konferensbidrag (refereegranskat)abstract
- Forced vibration tests have been conducted on the seven-storey timber building Eken in Mariestad inSweden. The main objective is to estimate the building’s dynamic properties from test data. The eigenfrequencies, modeshapes and their scaling are useful to calibrate numerical models. However, the most important outcomes are the estimatesof the modal damping values. The reason is that the damping impacts the acceleration, and thus the serviceability of thebuilding, and at the same time, it is very hard to model damping. So, during the design phase, one must rely on previoustest data (of which very few exist for taller timber buildings) or rule of thumbs. It is therefore important to gain knowledgeabout the damping for timber buildings in order to enable good designs of future and taller timber buildings. The test datashows that the modal damping is roughly equal to 2% of the critical viscous ones for the eigenmodes extracted. The testcampaign on Eken is made as a part of the project Dyna-TTB in which vibrational tests have been performed on eighthigh-rise timber buildings, in Europe, of which Eken is one.
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| 12. |
- Maharjan, Rajan, 1985-, et al.
(författare)
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Evaluation of hardening models to simulate joints in timber shear walls
- 2023
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Ingår i: World Conference on Timber Engineering WCTE 2023. - : World Conference on Timber Engineering 2023 (WCTE 2023). - 9781713873297 - 9781713873273 ; , s. 2709-2716
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Konferensbidrag (refereegranskat)abstract
- The properties of sheathing-to-framing joints considerably affect the load carrying capacity of a light-frame timber shear wall. A fastener with isotropic or kinematic hardening properties is modelled for the sheathing-to-framing joints with a zero-length element, with coupled properties in two perpendicular (orthogonal translational) directions to avoid the overestimation achieved with an uncoupled alternative. A single fastener experiment is performed to determine the elastic and plastic properties. For both fastener level and wall level modelling, monotonic as well as cyclic loading scheme is analysed. A concept of modelling the elasto-plastic coupled behaviour with hardening of the connector model for the fasteners is suggested. A damage response of the fastener is also studied to estimate the failure in load capacity of the connector model and decrease in the wall capacity after the maximum loading.
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| 13. |
- Mohaine, Siyimane, et al.
(författare)
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PERFORMANCE OF PASSIVE PROTECTION OF CROSS LAMINATED TIMBER DURING STANDARD FURNACE TESTS AND NATURAL FIRES
- 2023
-
Ingår i: 13th World Conference on Timber Engineering, WCTE 2023. - 9781713873297 ; 3, s. 1839-1847
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an experimental campaign designed to compare and understand the performance of passive protection under exposure to standard furnace tests and natural fires. As part of this campaign, five natural fire experiments were performed with partially protected cross-laminated timber (CLT) compartments under a range of ventilation conditions. In all the tests, only one side wall was left completely unprotected, and all other timber surfaces were protected with either two layers of 18 mm standard gypsum boards (GB) or two layers of 25 mm standard GBs. The structural CLT ceilings were subjected to a superimposed dead load of 1.35 kN/m² during the natural fire tests, and the fire load was (on average) 950 MJ/m²; chosen to represent the Eurocode 1991-1-2 characteristic value for dwellings. The performance of the passive protection was mainly evaluated with regards to the time to reach a protected timber surface temperature of 250°C. The testing confirms that the resulting fire protection performance of a given gypsum board layout depends on the ventilation conditions of the fire compartment, with more severe (and closest to ISO testing) outcomes when testing under ventilation-controlled scenarios. This paper provides data that sheds light on the co-dependency of the passive protection design and compartment fire dynamics and underlines the importance of considering the safety objectives of a building when defining the performance criteria of its structural elements.
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| 14. |
- Niklewski, Jonas, et al.
(författare)
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Simplified environmental analysis of the long-term performance of wood cladding and decking
- 2023
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Ingår i: 13th World Conference on Timber Engineering, WCTE 2023. - 9781713873273 - 9781713873297 ; 1, s. 549-557
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Konferensbidrag (refereegranskat)abstract
- The performance of timber in exposed environments is affected by several biotic and abiotic factors. For timber cladding and decking, two important aspects include reduced structural performance due to fungal decay and aesthetical changes resulting from superficial effects such as photodegradation and moulds. Predicting the long-term performance of timber is important because it enables rational material (species and treatment) and design (detailing) choices and reduce the risks of unexpected repairs and premature replacement of timber products. In this paper, we use available data on material performance in conjunction with environmental analysis to model, in a simplified way, (1) the time until onset of fungal decay and (2) the long-term aesthetical appearance of timber facades and decking. The results demonstrate how the analysis canbe used on a detailed geometry where wooden boards were modelled as separate objects and the choice of material affects the outcome. Several steps needing further development were identified, including a dose model linking microclimate to colour change and a better model for predicting moisture content. The study is part of a long-term effort to make holistic performance-based assessment of wood available for public use through easy-to-use procedures and accessible open-source software.
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| 15. |
- Ormarsson, Sigurdur, 1963-, et al.
(författare)
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Numerical and experimental study of glulam beams jointed with slotted-in steel plate connection
- 2023
-
Ingår i: 13th World Conference on Timber Engineering, WCTE 2023, Vol 2. - : World Conference on Timber Engineering (WCTE). - 9781713873297 ; , s. 1261-1268
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Konferensbidrag (refereegranskat)abstract
- The present work focuses on analysis of deformation and strength behaviour of slotted-in steel plateconnections in glued laminated timber (GLT). In Eurocode 5 (EC5), the design of metal dowel-type timber joints is basedon the yield theory presented by Johansen [1]. It consists of analytical expressions to calculate the lateral load-carryingcapacity of single fastener joints that exhibit different (plastic) failure modes. When designing optimised multiple fastenerconnections that are exposed to dominating moment action, the calculation of fastener forces and their directions duringprogressive plasticization of the dowel group is difficult to perform manually. Therefore, a simple numerical model tosimulate progressive elasto-plastic force development for every individual dowel is needed. This study presents new andsimple models to analyse the bending deformations of glulam beams jointed with mechanical slotted-in steel plateconnections. The proposed models were experimentally verified using results obtained from a joint project with theMaterial Testing Institute (MPA) at University of Stuttgart.
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| 16. |
- Pantak, Marek, et al.
(författare)
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Dynamic characteristics and dynamic response of timber footbridges to dynamic human activities
- 2023
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Ingår i: World Conference on Timber Engineering (WCTE 2023), 19-22 June, Oslo. - : World Conference on Timber Engineering 2023 (WCTE 2023). - 9781713873297 ; , s. 1930-1935
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Konferensbidrag (refereegranskat)abstract
- The dynamic action of footbridge users in different forms of activity (especially during walking andrunning) may cause an excessive vibration of the footbridge deck and may disturb the comfort of use of the structure. Thedynamic susceptibility of the footbridges varies depending on the construction material used to build the footbridge andthe typical construction solutions (construction details) resulting from the construction material used. The paper presentsthe basic dynamic characteristics of timber footbridges of various structural solutions, collected during dynamic field testsof these structures. The obtained results indicate relatively high dynamic resistance of timber footbridges to the dynamicloads generated by users under normal conditions of use. In addition, the results show that in the case of timberfootbridges, it is possible to consider changing the requirements of international standards defining the range of naturalfrequencies sensitive to the dynamic impact of users. In the case of timber footbridges, characterized by a relatively highself-weight (compared to steel footbridges), high stiffness and high damping, it is possible to consider changing therequirements for performing forced vibration analyses only for structures with fundamental vertical vibration frequency fv <= 3.0 Hz instead of the currently defined fv <= 5.0 Hz.
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| 17. |
- Perstorper, Mikael, et al.
(författare)
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Bending properties of 100 narrow clt-based boards – static and dynamic tests and DIC analysis
- 2023
-
Ingår i: World Conference on Timber Engineering WCTE 2023. - : World Conference on Timber Engineering 2023 (WCTE 2023). - 9781713873297 - 9781713873273 ; , s. 657-665
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Konferensbidrag (refereegranskat)abstract
- Production of CLT-panels typically results in 5-10% cut-offs due to window and door openings. CLT-boards can be made by slicing these cut-offs and finger-jointing them. This paper presents bending properties of 100 narrow CLT-boards (45x95x1800) made from 5-ply CLT panels made of Norway spruce. Alimited variation in E-modulus (CV=9%) and bending strength (CV=20%) was found with gross section values not far from typical structural C24-timber. The tests indicate that narrow CLT-boards have sufficient bending properties for being used as structural components, also where the bending capacity is formally utilized. However, the variation was slightly higher than for typical tests on larger CLT-elements (CV=8-16%), probably due to the smaller homogenization effect when fewer subparts carry the load. The rolling shear modulus was estimated to be Gr= 65MPa, which is to be expected due to the distance from the pith of the cross layerboards. The surprisingly high net flatwise bending strength (fm,05=49 MPa) can likely be attributed, for the most part, to the reinforcing effect from the cross layers that limit the slope of grain cracking near knots in the longitudinal layers. DIC-tests revealed an indication of a non-plane normal strain distribution over the beam depth in the shear-free zone between the inner loading points. This might lead to an under estimation of the shearfree local E-modulus according to EN408.
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| 18. |
- Poupet, Boris, 1995-, et al.
(författare)
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Estimation of moisture distribution in sawn timber using computed tomography
- 2023
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Ingår i: World Conference on Timber Engineering 2023 (WCTE 2023). - : Curran Associates, Inc.. - 9781713873273 - 9781713873297 ; , s. 759-765
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Konferensbidrag (refereegranskat)abstract
- Most of the physical, mechanical, and esthetic properties of wood products are affected by the drying of sawn timber. A better understanding of moisture transport in wood during kiln drying is necessary to obtain better quality products, shorter drying schedules, lower energy consumption, and a more sustainable process. Four-dimensional X-ray computed tomography (4DCT) (three-dimensional in space and one in time) with image processing techniques can be used to study the moisture content (MC) of sawn timber during kiln drying. The development of the technique is however made difficult by computational complexity and a lack of accurate experimental validation. In this study, a method relying on 4DCT has been developed using state-of-the-art image processing techniques. The method was validated by a regression analysis of the predicted MC against gravimetric measurements for different timber cross sections and different initial MC distributions on a significantly smaller scale than has previously been investigated. It is concluded that the MC can be estimated with an average uncertainty of ±4.8 percentage points on a 10 mm scale. Sawmills could ultimately benefit from a better understanding of wood-water interactions and dry sawn timber more efficiently.
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| 19. |
- Robert, Fabienne, et al.
(författare)
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NATURAL FIRE TESTS ON GLT COLUMNS INCLUDING THE COOLING DOWN PHASE
- 2023
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Ingår i: 13th World Conference on Timber Engineering, WCTE 2023. - : World Conference on Timber Engineering (WCTE). - 9781713873297 ; 3, s. 1848-1854, s. 1848-1854
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Konferensbidrag (refereegranskat)abstract
- This paper presents the data and the results of seven fire tests performed on glue laminated timber columns in a compartment built especially for the tests and in which timber wood cribs created a so-called natural fire. These tests are part of a research programme titled "burnout resistance" to establish a new methodology to better describe performance of structural elements during the whole duration of a fire. Comparisons with similar tests made in a fire resistance furnace allow comparing charring rates observed in standard conditions and in natural fires.
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| 20. |
- Schweigler, Michael, et al.
(författare)
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Moisture and Assembly History Effects on Embedment Properties of Steel Dowels in Spruce and Birch Loaded in Grain Direction
- 2023
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Ingår i: Proceedings from the 13th World Conference on Timber Engineering 2023. - : World Conference on Timber Engineering (WCTE). - 9781713873297 - 9781713873273 ; , s. 1146-1153
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Konferensbidrag (refereegranskat)abstract
- Embedment strength and stiffness of steel dowels in spruce and birch solid wood were investigated in an experimental study, taking into account the moisture and connection assembly history. Thus, in addition to the effect of different mechanical properties of wood at different moisture contents, the effect of changes in the moisture content between the steps of: drilling the dowel hole, assembly of the dowel, and testing of the specimen on the embedment strength and stiffness was studied. Full-hole embedment tests with 12 mm steel dowels showed a decrease in embedment strength with increasing wood moisture content, while the elastic embedment stiffness was not influenced. Drying the wood specimens after the dowel was inserted yielded up to 50% higher elastic embedment stiffness compared with connections drilled and assembled when the equilibrium moisture content was reached. Application of an artificial crack showed only a moderate effect on embedment strength and stiffness, while the ductile embedment behavior was maintained.
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| 21. |
- Sundqvist, Bror, et al.
(författare)
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Cross-laminated wood panels in a patient room and studies of interior environment
- 2023
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Ingår i: World conference on timber engineering 2023 (WCTE 2023). - : World Conference on Timber Engineering (WCTE). - 9781713873273 - 9781713873297 ; , s. 1062-1066
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Konferensbidrag (refereegranskat)abstract
- Studies on the effect from biobased materials and products on humans have indicated positive effects. This has earlier been shown in studies for e.g. hospitals, where indications of lower stress and pain in patients with wood as part ofinterior solutions. This paper describes the first step of a larger study that investigates the interior environment and the response of patients. The study presented here measured RH, temperature, emissions of volatile organic compounds (VOC) and microbial activities in two rooms at a hospital in Skellefteá, Orthopaedic ward. One room had a cross-laminated wood panel covering 42% ofwalls, window reveal and doors, and the other a control room with standard coverings. Results indicated only a small difference between the rooms in terms of temperature and RH. VOC emissions varied in both rooms but all concentrations were lower or much lower than threshold values for interior air quality standard limits. Biological contamination ofthe surfaces and from air sampling was also performed. Conclusions of this experimental study shows that from a regulatory perspective it is possible and safe to use wood as interior product.
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| 22. |
- Vessby, Johan, 1976-, et al.
(författare)
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Load levels and critical design issues in a multi-storey residential timber building built up by prefabricated volumetric elements
- 2023
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Ingår i: World Conference on Timber Engineering WCTE 2023. - : World Conference on Timber Engineering 2023 (WCTE 2023). - 9781713873297 - 9781713873273 ; , s. 4439-4446
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 23. |
- Vessby, Johan, 1976-, et al.
(författare)
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Structural use of cut-offs from clt-production – three examples that utilize the unique properties
- 2023
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Ingår i: World Conference on Timber Engineering WCTE 2023. - : World Conference on Timber Engineering 2023 (WCTE 2023). - 9781713873297 - 9781713873273 ; , s. 139-146
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Konferensbidrag (refereegranskat)abstract
- Production of CLT-panels typically results in 5-10% cut-offs due to window and door openings. CLT-boards can be made by slicing these cut-offs and finger-jointing them. It is worth while from economic and climatic aspects to find applications for such boards as building products with long service life. It is preferred to find uses where the premium transverse properties are utilized. This paper present three novel ideas for re-use of cut-offs from CLT. (a) The re-use as REX laminations in CLT production is a smart concept that minimize waste in an economical way. (b) By using finger-jointed CLT-boards as horizontal rails in timber frame buildings, the problems with over-load and deformations in multi-storey houses are minimized. (c) The capacity of glulam beams to carry concentrated loads is greatly enhanced by integrating CLT-boards as laminations.
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