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Behavior of Self-Tapping Screws Used in Hybrid Light Wood Frame Structures Connected to a CLT Core

https://research.thinkwood.com/en/permalink/catalogue3153
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Author
Eini, Ariya
Zhou, Lina
Ni, Chun
Organization
University of Victoria
FPInnovations
Editor
Branco, Jorge Manuel
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Keywords
Monotonic Test
Reversed-Cyclic Test
Connection Capacity
Ductility
Research Status
Complete
Series
Buildings
Summary
Light-frame wood structures are the most common type of construction for residential and low-rise buildings in North America. The 2015 edition of the National Building Code of Canada has increased the height limit for light-frame wood construction from 4 to 6 stories. With the increase in building height, it was noticed that light-frame wood structures may be governed by inter-story drift under wind and seismic loads. To reduce the inter-story drift, a hybrid system, consisting of CLT cores and light-frame structures, is proposed. The efficiency of this hybrid system is dependent on the performance of the connections between the two sub-systems. In this project, self-tapping screws (STSs) were used to connect the CLT core and light-frame wood structures on the floor level. Monotonic and reversed-cyclic tests were carried out on CLT-wood frame connections connected with STSs inserted at 45°, 90°, and mixed angles (45° and 90°). The connection performance was evaluated in terms of strength, stiffness, ultimate displacement, ductility, and energy dissipation capacity. Results show that a joint with STSs inserted at 45° had high stiffness and ductility but low energy dissipation, while connections with STSs installed at 90° had high ductility and energy dissipation but low stiffness. Connections with STSs inserted at mixed angles (45° and 90°) achieved the advantages of both configurations when the STSs were inserted at 45° or 90° individually, i.e., high stiffness, ductility, and energy dissipation. The ductility and energy dissipation were significantly improved compared with connections with STSs only inserted at 45° or 90°. This mixed angle connection can be an ideal design for connecting light-frame wood structures to a CLT core to resist wind and seismic load.
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Influence of inter-panel connections on vibration response of CLT floors due to pedestrian-induced loading

https://research.thinkwood.com/en/permalink/catalogue3340
Year of Publication
2023
Topic
Connections
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Milojevic, Marija
Racic, Vitomir
Marjanovic, Miroslav
Nefovska-Danilovic, Marija
Organization
University of Belgrade
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Connections
Acoustics and Vibration
Keywords
Walking Forces
Human-induced Vibrations
Single Surface Spline
Half-lapped Joint
Research Status
Complete
Series
Engineering Structures
Summary
Long-span cross-laminated timber (CLT) floors are typically an assembly of prefabricated CLT panels connected together on the site. The actual connections are commonly neglected in design calculations. Hence, a CLT floor is modelled either as a monolith slab or more frequently as a set of CLT panels with no connections at all. This paper presents a numerical study designed to examine the influence of two most common inter-panel connections, i.e. single surface spline and half-lapped joint, on vibration modes and vibration responses of a range of different CLT floors due to pedestrian-induced loading. Although the inter-panel connections are relatively complex in reality, they are modelled here as an equivalent 2D elastic strip between the CLT panels. This relatively simple yet robust model can be used with ease in design practice, regardless finite element (FE) software used to extract vibration modes of a CLT floor. The corresponding monolith floors and floors without inter-panel connections are studied for the comparison of the results. Vertical vibration responses are simulated for low-frequency and high-frequency floors using the corresponding walking force models given in a popular design guideline for footfall induced vibrations of civil engineering structures. Vibration responses were calculated for single pedestrian occupants and their walking paths parallel and perpendicular to the line of connection. The results showed that including the inter-panel connections in a FE model resulted in up to 2.5 higher RMS acceleration levels. Hence, the common practice of modelling CLT floors as monolith slabs or as a set of panels without connections should be left behind.
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Birch plywood as gusset plates in glulam frame via mechanical connectors: A combined experimental and numerical study

https://research.thinkwood.com/en/permalink/catalogue3348
Year of Publication
2023
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Wang, Yue
Wang, Tianxiang
Persson, Pontus
Hedlund, Patrik
Crocetti, Roberto
Wålinder, Magnus
Organization
KTH royal institute of technology
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Birch Plywood
Gusset Plate
Finite Element Method
Research Status
Complete
Series
Journal of Building Engineering
Summary
Birch is a short-lived hardwood species widespread in the Northern Hemisphere. Plywood made from birch has superior mechanical properties compared with that made from most softwoods, which makes it suitable for structural application. In this study, the feasibility of using birch plywood as gusset plates in timber-timber connections is presented. Test frames consisting of birch plywood gussets and glulam beams connected by nails were built and tested. A 2D analytical model based on truss theory and a 3D finite element model were proposed and constructed. Both models showed satisfactory agreements with the test results in terms of stiffness and strength. Tensile failure on the birch plywood gussets along the outermost row of nail holes was observed in the experiment. The observed failure modes and the stress distributions in the 3D numerical model suggest that the spreading angle (Whitmore effective width) theory should be considered in the design phase of birch plywood gusset plates. Besides, a modified spreading angle theory is proposed to both approximate the stress distribution and predict the load-bearing capacity.
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Influence of glue-free zones on the withdrawal capacity of glued-in steel threaded rods

https://research.thinkwood.com/en/permalink/catalogue3376
Year of Publication
2023
Topic
Mechanical Properties
Connections
Author
Pugovics, Karlis
Spulle, Uldis
Arhipova, Irina
Grants, Edvins
Klancbergs, Kristians
Organization
Latvia University of Life Sciences and Technologies
Year of Publication
2023
Format
Journal Article
Topic
Mechanical Properties
Connections
Keywords
Glued-in Steel Treaded Rod
Glue-free Zone
Withdrawal Capacity
Destructive Testing
Research Status
Complete
Series
BioResources
Summary
The hidden nature of a glued-in rod joint presents considerable challenges with regards to quality control, and there has been minimal research on the subject to fully understand the influence of defects on the joint performance. In this study, voids in adhesive line or glue-free zones were simulated in various depths of the embedded rod, and the results were compared to a reference sample population without defects. Withdrawal capacity of glued-in steel threaded rods were lower compared to reference group samples without gluing defects, when glue simulated voids or glue-free zones were positioned in the middle part and upper (closer to sample crosscut surface) part of the glued-in rods. And no difference was observed of simulated glue-free zones in the lower (the deepest) part, closer to the end of the glued-in rod, compared to reference group samples without gluing defects.
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Design Approach for CLT Connections

https://research.thinkwood.com/en/permalink/catalogue3333
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Author
Mohammad, Mohammad
Blass, Hans
Salenikovich, Alexander
Ringhofer, Andreas
Line, Philip
Rammer, Douglas
Smith, Tobias
Li, Minghao
Organization
Natural Resources Canada
Karlsruhe Institute of Technology
Laval University
Graz University of Technology
American Wood Council
USDA Forest
PTL Structural Consultants
Publisher
PKP Publishing Services Network
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Keywords
Eurocode 5
CSA O86
NDS
NZ 3603
Embedment
Withdrawal
Research Status
Complete
Series
Wood and Fiber Science
Summary
Various design approaches for establishing the resistance of connections in cross-laminated timber (CLT) structures have been developed and adopted in timber design standards worldwide. Although the fundamental principles are similar, the new design provisions for CLT connections have been aligned in some standards with the existing design philosophy and format adopted for sawn timber and glulam using traditional fasteners such as dowels, nails, and wood screws for consistency and simplicity, in the other standards, alternate approaches have been developed. This article presents a snap shot of the various design approaches for connections in CLT adopted in Europe, Canada, the United States, and New Zealand. The intent is for the reader to have a better knowledge of the underpinning assumptions, principles, and the adopted design rules in each of these standards.
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Investigations of connection detailing and steel properties for high ductility doweled timber connections

https://research.thinkwood.com/en/permalink/catalogue3110
Year of Publication
2022
Topic
Connections
Material
LVL (Laminated Veneer Lumber)
Author
Geiser, M.
Furrer, L.
Kramer, L.
Blumer, S.
Follesa, M.
Organization
Bern University of Applied Sciences
sblumer ZT Gmbh
dedaLEGNO
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Topic
Connections
Keywords
Doweled Connections
Capacity Design
Displacement Ductility
Fully Confined Timber Member
Notch Effect Restraining Measures
Post-elastic Steel Properties
Constriction of Dowels
Research Status
Complete
Series
Construction and Building Materials
Summary
According to Eurocode 8 moderate to high dissipative behaviour of timber structures requires sufficient ductility of the critical regions. Earlier experiments on timber connections with slotted-in steel plates and laterally loaded common steel dowels rarely achieved high ductility values. Connections consisting of LVL-C members, dowel-type fasteners with different post-elastic steel properties, full confinement of the timber member and measures to restrain the notch effect were investigated by means of monotonic and cyclic tests with regards to the displacement ductility. The measures taken proved to be effective in enhancing the plastic deformation capacity of the steel dowels to a large extent. However, a new aspect was observed: the constriction of the dowels in the contact area with the plate. The research results provided a better understanding of the factors influencing the behaviour of slotted-in steel plate connection.
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Mechanical Behavior of GFRP Dowel Connections to Cross Laminated Timber-CLT Panels

https://research.thinkwood.com/en/permalink/catalogue2957
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Almeida, Amanda
Moura, Jorge
Organization
Maringá State University
Londrina State University
Editor
Knapic, Sofia
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Connections
Keywords
GFRP
Dowel-Type Connections
Panel-to-Panel
Design Methodology
Push-Out Tests
Research Status
Complete
Series
Forests
Summary
Sustainability issues are driving the civil construction industry to adopt and study more environmentally friendly technologies as an alternative to traditional masonry/concrete construction. In this context, plantation wood especially stands out as a constituent of the cross-laminated timber (CLT) system, laminated wood glued in perpendicular layers forming a solid-wood structural panel. CLT panels are commonly connected by screws or nails, and several authors have investigated the behavior of these connections. Glass-fiber-reinforced polymer (GFRP) dowels have been used to connect wooden structures, and have presented excellent performance results; however, they have not yet been tested in CLT. Therefore, the objective of this study is to analyze the glass-fiber-reinforced polymer (GFRP)-doweled connections between CLT panels. The specimens were submitted to monotonic shear loading, following the test protocol described in EN 26891-1991. Two configurations of adjacent five-layer panels were tested: flat-butt connections with 45° dowels (x, y, and z axes), and half-lap connections with 90° dowels. The results were evaluated according to the mechanical connection properties of strength, stiffness, and ductility ratio. The results showed higher stiffness for butt-end connections. In terms of strength, the half-lap connections were stronger than the butt-end connections.
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Brittle failure of laterally loaded self-tapping screw connections for cross-laminated timber structures

https://research.thinkwood.com/en/permalink/catalogue3120
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Author
Azinovic, Boris
Cabrero, José Manuel
Danielsson, Henrik
Pazlar, Tomaž
Organization
Slovenian National Building and Civil Engineering Institute
University of Navarra
Lund University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Keywords
Brittle Failure
Analytical Model
Overstrength
Research Status
Complete
Series
Engineering Structures
Summary
The performance of structural timber connections is of utmost importance since they control the global response of the building. A ductile failure mechanism on the global scale is desirable, especially in the design of structures in seismic areas, where dissipative components in which ductile failure modes need to be ensured are considered. Therefore, the knowledge of possible brittle failure modes of connections is crucial. The paper investigates the brittle failures of laterally loaded dowel-type connections in cross-laminated timber subjected to tensile load in a lap joint configuration through experimental investigations and analytical estimations. A set of 13 different test series has been performed with fully threaded self-tapping screws of 8 mm diameter and different lengths (40 to 100 mm) in cross-laminated timber composed of 3 or 5 layers (layer thickness range from 20 to 40 mm), giving rise to the activation of different brittle failure modes at different depths. Plug shear was among the most typically observed failure modes. A previously proposed model for the brittle capacity was applied to the tested connections at the characteristic level. As shown by the performed statistical analysis, the existing model is not reliable and mainly unconservative. A very low performance is observed (CCC = 0.299), but with a good correlation (c = 0.750) for the tests in the parallel direction. Further research work is required to improve the current model predictions and to gain a better understanding of the underlying resisting mechanisms.
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A study on beam-to-column moment-resisting timber connections under service load, comparing full-scale connection testing and mock-up frame assembly

https://research.thinkwood.com/en/permalink/catalogue3116
Year of Publication
2022
Topic
Connections
Application
Frames
Author
Vilguts, Aivars
Nesheim, Sveinung Ørjan
Stamatopoulos, Haris
Malo, Kjell Arne
Organization
Norwegian University of Science and Technology
Publisher
Springer
Year of Publication
2022
Format
Journal Article
Application
Frames
Topic
Connections
Keywords
Moment-resisting Connection
Semi-rigid Connection
Screwed-in Threaded Rods
Experimental Modal Analysis
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
A new timber frame structural system consisting of continuous columns, prefabricated hollow box timber decks and beam-to-column moment-resisting connections is investigated. The hollow box timber decks allow long spans with competitive floor height and efficient material consumption. To achieve long spans, semi-rigid connections at the corners of deck elements are used to join the columns to the deck elements. In the present paper, experimental investigations of a semi-rigid moment-resisting connection and a mock-up frame assembly are presented. The semi-rigid connection consists of inclined screwed-in threaded rods and steel coupling parts, connected with friction bolts. Full-scale moment-resisting timber connections were tested under monotonic and cyclic loading to quantify rotational stiffness, energy dissipation and moment resistance. The mock-up frame assembly was tested under cyclic lateral loading and with experimental modal analysis. The lateral stiffness, energy dissipation, rotational stiffness of the connections and the eigen frequencies of the mock-up frame assembly were quantified based on the experimental tests in combination with a Finite Element model, i.e., the model was validated with experimental results from the rotational stiffness tests of the beam-to-column connections. Finally, the structural damping measured with experimental modal analysis was evaluated and compared with FE model using the material damping of timber parts and equivalent viscous damping of the moment-resisting connections.
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An experimental study of the stiffness and strength of cross-laminated timber wall-to-floor connections under compression perpendicular to the grain

https://research.thinkwood.com/en/permalink/catalogue3197
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Schweigler, Michael
Akter, Shaheda T.
Sabaa, Stephen
Bader, Thomas K.
Organization
Linnaeus University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Connections
Keywords
Compression Perpendicular To Grain
Stress Dispersion
Nominal Stiffness
Nominal Strength
Digital Image Correlation
Research Status
Complete
Series
Engineering Structures
Summary
In platform-type multi-story cross-laminated timber (CLT) buildings, gravity loads from upper floors, and vertical reaction forces from horizontal actions, like wind loads, cause substantial compressive forces in the CLT-floor elements. The combination of these high forces with a comparable low compression stiffness and strength perpendicular to the grain of timber, makes the compression perpendicular to the grain (CPG) verification of CLT an important design criterion. In this experimental study, CPG of CLT was investigated by means of typical wall-to-floor connections in CLT platform-type structures. CLT-wall elements were used for load application to transmit forces through the CLT-floor element by CPG. Compared to load application by steel elements, as it commonly is done in experiments, lower stiffness but similar strength were found for CLT walls. The study of different connection types showed the highest stiffness and strength for connections assembled with screws, followed by pure wood-to-wood contact, while connections with acoustic layers between the floor and wall elements showed the lowest stiffness and strength. In addition, these connections were tested for center and edge load position on the CLT-floor element. The strength for center and edge position compared to full surface loaded specimens increased linearly with the activated material volume, as determined by earlier proposed stress dispersion models. The stress dispersion effect was visualized by surface strain measurements using digital image correlation technique. Also, the stiffness increased with the activated material volume. Stress dispersion in the CLT-floor allowed to explain the increase in stiffness and strength with decreasing CLT-wall thickness. Strength values at different strain levels, and stiffness and strength increase factors suitable for the engineering design of CLT structures are provided.
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Moment-resisting beam-to-column timber connections with inclined threaded rods: Structural concept and analysis by use of the component method

https://research.thinkwood.com/en/permalink/catalogue3132
Year of Publication
2022
Topic
Connections
Author
Stamatopoulos, Haris
Malo, Kjell Arne
Vilguts, Aivars
Organization
Norwegian University of Science and Technology
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Topic
Connections
Keywords
Moment-resisting Connection
Threaded Rod
Rotational Stiffness
Research Status
Complete
Series
Construction and Building Materials
Summary
The use of moment-resisting frames with semi-rigid connections as a lateral load-carrying system in timber buildings can reduce the need for bracing with diagonal members or walls and allow for more open and flexible architecture. The overall performance of moment-resisting frames depends largely on the properties of their connections. Screwed-in threaded rods with wood screw thread feature high axial stiffness and capacity and they may be used as fasteners in beam-to-column, moment-resisting timber connections. In the present paper, a structural concept for a beam–to-column, moment-resisting timber connection based on threaded rods is presented and explained. Analytical expressions for the estimation of the rotational stiffness and the forces in the rods were derived based on a component-method approach. The analytical predictions for stiffness were compared to experimental results from full scale tests and the agreement was good.
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Theoretical and experimental study on laterally loaded nailed bamboo connection

https://research.thinkwood.com/en/permalink/catalogue3121
Year of Publication
2022
Topic
Connections
Material
Other Materials
Author
Malkowska, Dominika
Norman, James
Trujillo, David
Organization
University of Bristol
Coventry University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Other Materials
Topic
Connections
Keywords
Bamboo Connection
Nailed Bamboo Connection
Dowelled Bamboo Connection
Research Status
Complete
Series
Construction and Building Materials
Summary
The aim of the study was to create and verify a theoretical model for single-shear steel to bamboo nailed connections in natural bamboo. To this end, existing timber strength and fracture theories were used to model the brittle and ductile failure strength of the studied bamboo connection. Experimental tests of steel to bamboo nailed connection subjected to short-term loading in single shear parallel to fibre direction in Moso bamboo confirmed the suitability of the timber models to predict the connection behaviour. The findings constitute a basis for development of theory for screws, which is the advocated connector type by the authors. It is anticipated that the predictability of bamboo dowelled connection behaviour, along with the latest developments in bamboo design standardization, will enhance the designers confidence to implement dowelled bamboo connections in practice.
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Limited-damage 3D-printed interlocking connection for timber volumetric structures: Experimental validation and computational modelling

https://research.thinkwood.com/en/permalink/catalogue3196
Year of Publication
2022
Topic
Connections
Author
Li, Zhengyao
Tsavdaridis, Konstantinos Daniel
Organization
University of Leeds
University of London
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Topic
Connections
Keywords
Volumetric Construction
Interlocking Connection
Connection Test
3D Print
Research Status
Complete
Series
Journal of Building Engineering
Summary
Cross laminated timber volumetric construction (CLTVC) is an innovative construction technology that combines the sustainability of timber and the efficiency of modular construction, as opposed to conventional construction. However, the connection installing methods of CLTVC, such as fastening, are laborious with limited accessibility for connection installations, thus hindering the application of CLTVC in mid- and high-rise structures. Therefore, a new way of connecting CLT modules by sliding and stacking is explored herein with a proposed damage-control interlocking connection system, aiming to provide a more efficient assembly solution to CLTVC that does not require onsite screwing. Quasi-static monotonic and cyclic test, and numerical analyses were conducted to assess the mechanical performance of the proposed connections, which possessed adequate translational stiffness and strength of the proposed connections. The connections' ability to control deformation – damage is moved away from timber and the embedded fasteners, was also well demonstrated in the test, as both screws and timber remained mostly intact after testing. The proposed connection design showcases a new concept of modules’ assembly in volumetric construction with higher efficiency and flexibility; meanwhile demonstrates the potential in reducing the permanent damage to structural materials during service life and enabling reuse.
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Statistical correlation investigation of a single-doweled timber-to-timber joint

https://research.thinkwood.com/en/permalink/catalogue3193
Year of Publication
2022
Topic
Connections
Author
Aquino, Caroline D.
Rodrigues, Leonardo G.
Branco, Jorge M.
Gomes, Wellison J.S.
Organization
University of Minho
Federal University of Santa Catarina
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Topic
Connections
Keywords
Timber Joints
Uncertainty Quantification
Joint Behavior
Copula Theory
Reliability Analysis
Research Status
Complete
Series
Engineering Structures
Summary
Dowel-type joints are widely used in timber structures given their ease of construction, strength, and capacity to deform before failure. The embedment strength of timber and the bending moment capacity of dowels are considered key properties in the design. On the other hand, these properties have an inherent variability that increases the uncertainties related to the connection’s strength and associated failure modes. This study proposes to quantify the uncertainty related to the statistical correlation behavior between the timber embedment strength and dowel bending moment capacity while comparing analytical solutions to the results of double shear single doweled timber joints. Traditional distribution fitting procedures, as well as copula functions, are implemented to capture their marginal and dependence behavior. Since their source of mutual correlation is known, the effectiveness of the different approaches in describing the statistical dependence structure can be assessed. This is done by investigating how equivalent are the descriptions of dependence by copula functions and directly from the correlation origin. Results obtained here indicate that, for single dowel-type connections in double shear, the impact of the copulas on the results is small, which means that improving their joint characterization represents a minor improvement in the reliability results. Besides the minor differences, the results show that copula functions are a viable tool capable of capturing the nuances of the joint behavior between random variables.
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The influence of inaccuracies in the production process on the load-bearing behaviour of timber step joints

https://research.thinkwood.com/en/permalink/catalogue3115
Year of Publication
2022
Topic
Connections
Application
Trusses
Author
Braun, Matthias
Kromoser, Benjamin
Organization
University of Natural Resources and Life Sciences Vienna
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Application
Trusses
Topic
Connections
Keywords
Timber Joints
Timber Truss
Step-joint
Carpentry Joints
Resource Efficiency
Research Status
Complete
Series
Construction and Building Materials
Summary
Inaccuracies within timber step joints are a perennial problem of the wood construction industry. Even perfectly constructed carpentry step joints can become imperfect due to a change in moisture content. The predominant question when looking at step joints with gaps is to what extent the load-bearing behaviour is influenced by these inaccuracies. The authors look beyond this question and investigate if intentionally manufactured gaps could have a positive influence on the load-bearing behaviour and the failure mode of regular and newly designed carpentry joints.
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The Effect of GFRP Wrapping on Lateral Performance of Double Shear Lap Joints in Cross-Laminated Timber as a Part of Timber Bridges

https://research.thinkwood.com/en/permalink/catalogue3211
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Bridges and Spans
Author
Haftkhani, Akbar Rostampour
Rashidi, Maria
Abdoli, Farshid
Gerami, Masood
Organization
University of Mohaghegh Ardabili
Western Sydney University
University of Tehran
Editor
Sadowski, Thmasz
Branco, Jorge Manuel
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Bridges and Spans
Topic
Connections
Keywords
GFRP
Lag Screw
Lateral Resistance
Timber Bridges
Research Status
Complete
Series
Buildings
Summary
Timber elements, such as timber bridges, are exposed to heavy loads. Therefore, reinforcement might be useful. Due to a lack of wood supplies, poplar, a fast-growing tree, could be used to construct CLT (cross-laminated timber). The low density of fast-growing wood species directly impacts the mechanical properties of CLT. Therefore, in this study, a CLT panel was reinforced with GFRP (glass-fiber-reinforced polymer), and the lateral resistance of double shear lap joints in reinforced CLTs with 0-90-0° arrangements in two strength directions was investigated. Lag screws (Ø = 8 mm) at the end distances of 1 and 3 cm were employed for making the lateral test specimens. First, the effect of the number of GFRP layers on lateral resistance of the joints was investigated. The results revealed that, as the number of GFRP layers changed from one to three, the lateral resistance increased by 45.47%, and then, by four layers, it decreased by 1.3%. Since the joints with three layers of FRP had the highest strength, the effects of the end distance and the CLT panel strength directions on the lateral performance of the reinforced and non-reinforced specimens were investigated. The results indicated that the lateral resistance of reinforced CLTs with GFRP was about 26.5% more than the unreinforced ones. Moreover, CLTs in the major strength direction showed 4.2% more lateral resistance than those in the minor strength direction. Moreover, lag screws at the end distance of 3 cm had 60% more lateral resistance than those at the end distance of 1 cm. In terms of failure modes, bearing, shear, and net-tension modes were observed in the CLTs, while Is, IIIs, and IV modes were observed in the lag screws.
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Structural Behaviour of Aluminium–Timber Composite Beams with Partial Shear Connections

https://research.thinkwood.com/en/permalink/catalogue3388
Year of Publication
2023
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Chybinski, Marcin
Polus, Lukasz
Organization
Poznan University of Technology
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Mechanical Properties
Keywords
Aluminium-Timber Composite Beams
Partial Shear Connection
Screws
Bending Test
Finite Element Method
Research Status
Complete
Series
Applied Sciences
Summary
In this paper, the short-term behaviour of innovative aluminium–timber composite beams was investigated. Laminated veneer lumber panels were attached to aluminium beams with screws. Recently conducted theoretical, experimental, and numerical investigations have focused on aluminium–timber composite beams with almost full shear connections. However, no experiments on aluminium–timber composite beams with partial shear connections have yet been conducted. For this reason, composite action in composite beams with different screw spacing was studied in this paper. Four-point bending tests were performed on aluminium–timber composite beams with different screw spacing to study their structural behaviour (ultimate load, mode of failure, load versus deflection response, load versus slip response, and short-term stiffness). The method used for steel–concrete composite beams with partial shear connection was adopted to estimate the load bearing capacity of the investigated aluminium–timber composite beams. The resistance to sagging bending of the aluminium–timber composite beams with partial shear connections from the theoretical analyses differed by 6–16% from the resistance in the laboratory tests. In addition, four 2D numerical models of the composite beams were developed. One model reflected the behaviour of the composite beam with full shear connection. The remaining models represented the composite beams with partial shear connections and were verified against the laboratory test results. Laminated veneer lumber was modelled as an orthotropic material and its failure was captured using the Hashin damage model. The resistance to sagging bending of the aluminium–timber composite beams with partial shear connections from the numerical analyses were only 3–6% lower than the one from the experiments.
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Experimental investigation of the moment-rotation behaviour of beam-column connections produced using compressed wood connectors

https://research.thinkwood.com/en/permalink/catalogue3104
Year of Publication
2022
Topic
Mechanical Properties
Connections
Material
DLT (Dowel Laminated Timber)
Author
Mehra, Sameer
O'Ceallaigh, Conan
Sotayo, Adeayo
Guan, Zhongwei
Harte M. Annette
Organization
National University of Ireland
University of Liverpool
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
DLT (Dowel Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
Compressed Wood
Moment-Rotation Behaviour
Dowel Type Connections
Research Status
Complete
Series
Construction and Building Materials
Summary
The use of timber in construction in medium–high rise construction has increased in recent years largely due to the significant innovation in engineered wood products and connection technology coupled with a desire to utilise more environmentally sustainable construction materials. While engineered wood products offer a low-carbon solution to the construction industry, the widespread use of adhesive and metallic fasteners often limits the recyclability of the structural components at the end of life of the structure and it may be beneficial to reduce this where possible. To establish the possibility of an all-wood connection solution, this preliminary study examines a series of beam-column connections designs to evaluate the relative performance of the different designs, which are connected with modified or compressed wood (CW) connectors. The connection designs are formed between glued-laminated beam and column members in the first instance and later examined when connecting dowel-laminated timber (DLT) members. The results show that significant moment capacity and rotational stiffness can be achieved for connections solely connected using CW fasteners. Furthermore, the all-wood solution utilising CW fasteners to connect DLT members has also demonstrated significant moment capacity and rotational stiffness capacity without the use of adhesive and metallic components.
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Analysis and Tests of Lateral Resistance of Bolted and Screwed Connections of CLT

https://research.thinkwood.com/en/permalink/catalogue2956
Year of Publication
2022
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Huo, Liangliang
Zhu, Enchun
Niu, Shuang
Wu, Guofang
Organization
Harbin Institute of Technology
China Academy of Forestry
Editor
Ozarska, Barbara
Monaco, Angela
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Connections
Keywords
Lateral Resistance
European Yield Model
Bolt Connection
Screw Connectors
Emdedment Stress
Research Status
Complete
Series
Forests
Summary
The lateral resistance of dowel-type connections with CLT is related to its lay-up, species of the laminations and even the manufacture method. Treating the CLT as homogeneous material, current methods develop new equations through test results or make use of the existing equations for the embedment strength already used in design codes; thus, the lateral resistance of dowel-type connections of CLT can be calculated. This kind of approach does not take the embedment stress distribution into account, which may lead to inaccuracy in predicting the lateral resistance and yield mode of the dowel-type connections in CLT. In this study, tests of the bolted connections and the screwed connections of CLT were conducted by considering the effects of the orientation of the laminations, the thickness of the connected members, the fastener diameter and strength of the materials. The material properties including yield strength of the fasteners and embedment strength of the CLT laminations were also tested. Using analysis of the dowel-type connections of CLT by introducing the equivalent embedment stress distribution, equations for the lateral resistance of the connections based on the European Yield Model were developed. The predicted lateral resistance and yield modes were in good agreement with the test results; the correctness and the feasibility of the equations were thus validated.
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Mechanical Behaviour of Aluminium-Timber Composite Connections with Screws and Toothed Plates

https://research.thinkwood.com/en/permalink/catalogue3061
Year of Publication
2022
Topic
Connections
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Author
Chybinski, Marcin
Polus, Lukasz
Organization
Poznan University of Technology
Editor
Sorrentino, Andrea
Chen, Daolun
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Topic
Connections
Mechanical Properties
Keywords
Aluminium-Timber Structures
Toothed Plate
Screwed Connection
Shear Connection
Push-out Test
Research Status
Complete
Series
Materials
Summary
This paper presents an investigation of the load-slip behaviour of aluminium-timber composite connections. Toothed plates with bolts are often used for connecting timber structural members with steel structural members. In this paper, toothed plates (C2-50/M10G, C2-50/M12G or C11-50/M12) have been used as reinforcement in aluminium-timber screwed connections for the first time. The push-out test specimens consisted of laminated veneer lumber slabs, aluminium alloy beams, and hexagon head wood screws (10 mm × 80 mm and 12 mm × 80 mm). Of the specimens, 12 additionally had toothed plates as reinforcement, while 8 had no reinforcement. The load carrying-capacity, the mode of failure and the load-slip response of the strengthened and non-strengthened screwed connections were investigated. The use of toothed plate connectors was found to be effective in increasing the strength of aluminium-timber composite connections and ineffective in improving their stiffness. The examined stiffness and strength of the connections can be used in the design and numerical modelling of aluminium-timber composite beams with reinforced screwed connections.
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