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Analysis of Shear Transfer and Gap Opening in Timber–Concrete Composite Members with Notched Connections

https://research.thinkwood.com/en/permalink/catalogue1399
Year of Publication
2017
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
Author
Boccadoro, Lorenzo
Steiger, René
Zweidler, Simon
Frangi, Andrea
Publisher
Springer Netherlands
Year of Publication
2017
Format
Journal Article
Material
Timber-Concrete Composite
Topic
Connections
Mechanical Properties
Keywords
Notched Connections
Analytical Model
Shear Stress
Failure
Research Status
Complete
Series
Materials and Structures
Summary
In timber–concrete composite members with notched connections, the notches act as the shear connections between the timber and the concrete part, and have to carry the shear flow necessary for composite action. The shear transfer through the notches generates shear and tensile stresses in both parts of the composite member, which may lead to brittle failure and to an abrupt collapse of the structure. Although simplified design formulas already exist, some structural aspects are still not clear, and a reliable design model is missing. This paper summarizes current design approaches and presents analytical models to understand the shear-carrying mechanism, to estimate the shear stresses acting in the timber and concrete, and to predict failure. The analysis concentrates on three problems: the shearing-off failure of the timber close to the notch, the shear failure of the concrete, and the influence of the shear flow on the gap opening between the timber and concrete. Parts of the model calculations could be compared to experimental observations. The conclusions of this paper contribute to improving current design approaches.
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Behaviour of Mechanically Laminated CLT Members

https://research.thinkwood.com/en/permalink/catalogue291
Year of Publication
2015
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Kuklík, Petr
Velebil, Lukáš
Publisher
IOP Publishing Ltd
Year of Publication
2015
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Connections
Mechanical Properties
Keywords
Shear Stress
Torsional Stiffness
Slip Modulus
Lamination
Conference
International Conference on Innovative Materials, Structures and Technologies
Research Status
Complete
Notes
September 30-October 2 2015, Riga, Latvia
Summary
Cross laminated timber (CLT) is one of the structural building systems based on the lamination of multiple layers, where each layer is oriented perpendicularly to each other. Recent requirements are placed to develop an alternative process based on the mechanical lamination of the layers, which is of particular interest to our research group at the University Centre for Energy Efficient Buildings. The goal is to develop and verify the behaviour of mechanically laminated CLT wall panels exposed to shear stresses in the plane. The shear resistance of mechanically jointed CLT is ensured by connecting the layers by screws. The paper deals with the experimental analysis focused on the determination of the torsional stiffness and the slip modulus of crossing areas for different numbers of orthogonally connected layers. The results of the experiments were compared with the current analytical model.
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Cross Laminated Timber at In-Plane Beam Loading – Prediction of Shear Stresses in Crossing Areas

https://research.thinkwood.com/en/permalink/catalogue1305
Year of Publication
2018
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams
Author
Danielsson, Henrik
Serrano, Erik
Publisher
ScienceDirect
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
In-Plane Loading
Eurocode 5
Strength
Shear Stress
Crossing Areas
Research Status
Complete
Series
Engineering Structures
Summary
Cross Laminated Timber (CLT) at in-plane beam loading conditions present a very complex stress state and many failure modes need to be considered in design. The work presented here aims at finding improvements of a specific analytical model for stress analysis and strength verification that has been suggested in literature and which is also suggested as a basis for design equations for the next version of Eurocode 5. Although the model has appealing properties it suffers from some drawbacks related to the assumed distributions of internal forces which, based on comparison to finite element analysis, appear to be inaccurate. The main focus in this paper is on model predictions regarding the distribution and magnitude of internal forces acting in the crossing areas between longitudinal and transversal laminations. The proposed modified model assumptions regarding the distribution of lamination shear forces, which in turn influence the forces acting in the crossing areas, are suggested to be taken into account in design of CLT beams.
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Cross Laminated Timber (CLT) – Reinforcements with Self-Tapping Screws

https://research.thinkwood.com/en/permalink/catalogue1487
Year of Publication
2010
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Mestek, Peter
Winter, Stefan
Year of Publication
2010
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Concentrated Loads
Self-Tapping Screws
FEM
Rolling Shear Stress
Compression
Strengthening
Load Bearing
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
June 20-24, 2010, Riva del Garda, Italy
Summary
This paper illustrates a research project about the calculation and design of Cross Laminated Timber (CLT) elements stressed by concentrated loads. Its focus lies on the shear design of CLT-elements next to punctual supports including reinforcements with self-tapping screws with continuous threads in areas of high shear stresses. Different influencing parameters on the distribution of shear forces next to a punctual support were evaluated by using comparative FEM-analyses. In the course of laboratory tests material-mechanical principles were determined to consider the interaction of rolling shear stresses and compression perpendicular to the grain. In addition to FEM simulations several experimental tests were carried out to describe the load bearing behaviour and the strengthening effect of CLT-elements reinforced by self-tapping screws. The investigations aim at developing a design concept including the effects mentioned above.
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Design Concept for CLT - Reinforced with Self-Tapping Screws

https://research.thinkwood.com/en/permalink/catalogue1486
Year of Publication
2014
Topic
Mechanical Properties
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Mestek, Peter
Dietsch, Philipp
Organization
Technical University of Munich
Year of Publication
2014
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Design and Systems
Keywords
Self-Tapping Screws
Shear Stress
Rolling Shear Stress
Research Status
Complete
Summary
Concentrated loads on Cross Laminated Timber elements (CLT) in areas of point supports or load applications cause high local shear stresses. Inclined self-tapping screws with continuous threads have turned out to be an effective reinforcement. As neither the German design standard DIN 1052 nor technical approvals cover this construction method a research project funded by the AiF was conducted to gather basic information for its application. These basics include the determination of shear stresses next to concentrated loads, the interaction of compression perpendicular to the grain and rolling shear stresses as well as theoretical and experimental examinations of the load bearing behaviour of reinforced CLT-elements. This paper presents the main research results. A design concept validated by means of the test results is proposed.
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Low Cycle Fatigue Tests and Damage Accumulation Models on the Rolling Shear Strength of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1448
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Li, Yuan
Lam, Frank
Publisher
Springer Japan
Year of Publication
2016
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Rolling Shear Strength
Rolling Shear Stress
Duration of Load
Fatigue Tests
Damage
Research Status
Complete
Series
Journal of Wood Science
Summary
This paper presents a study on rolling shear damage accumulation and duration of load of cross-laminated timber (CLT) with low cycle fatigue tests. The study of the duration-of-load (DOL) effect on strength properties of wood products is typically challenging; it may be more challenging for non-edge-glued CLT considering crosswise layups of wood boards, existing gaps, and non-uniform stress distributions in cross layers. In experimental studies, short-term ramp loading tests and low cycle trapezoidal fatigue loading tests were used to study the DOL behaviour of the CLT rolling shear. The ramp tests were performed to establish the short-term CLT rolling shear strength properties. The low cycle trapezoidal fatigue tests were performed to evaluate the damage accumulation process for the matched specimens under controlled rolling shear stress levels. A stress-based damage accumulation model was further used to investigate the rolling shear DOL effect with model parameters treated as random variables calibrated against one set of the test data. The calibrated model predicted well comparing with the other set of the test data. This verified model provides a robust tool to quantify the DOL effect on rolling shear strength in the core layers of CLT that can be used in future studies of DOL behaviour in CLT under arbitrary loading histories.
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Self-Tapping Screws and Threaded Rods as Reinforcement for Structural Timber Elements - A State-Of-The-Art Report

https://research.thinkwood.com/en/permalink/catalogue448
Year of Publication
2015
Topic
Connections
Serviceability
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Author
Dietsch, Philipp
Brandner, Reinhard
Publisher
ScienceDirect
Year of Publication
2015
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Topic
Connections
Serviceability
Keywords
Reinforcement
Threaded Rods
Self-Tapping Screws
Shear Stress
Europe
Research Status
Complete
Series
Construction and Building Materials
Summary
In timber engineering, self-tapping screws, optimized primarily for axial loading, represent the state-of-the-art in fastener and reinforcement technology. Their economic advantages and comparatively easy handling make them one of the first choices for application in both domains. This paper focuses on self-tapping screws and threaded rods applied as reinforcement, illustrating the state-of-the-art in application and design approaches in Europe, in conjunction with numerous references for background information. With regard to medium to large span timber structures which are predominately erected by using linear timber members, from e.g. glued laminated timber, the focus of this paper is on their reinforcement against stresses perpendicular to grain as well as shear. However, latest findings with respect to cross laminated timber are included as well.
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Structural Analysis of In-Plane Loaded CLT Beams

https://research.thinkwood.com/en/permalink/catalogue1213
Year of Publication
2017
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams
Author
Jelec, Mario
Strukar, Kristina
Rajcic, Vlatka
Organization
University of Osijek
Year of Publication
2017
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
In-Plane Loading
Shear Stress
Failure Modes
FE Analysis
Eurocode 5
Research Status
Complete
Series
e-GFOS
Summary
Cross laminated timber (CLT) is a versatile engineered timber product that is increasingly well-known and of global interest in several applications such as full size plane or linear timber elements. The aim of this study involves investigating the performance of CLT beams loaded in-plane by considering bending and shear stress analysis with a special emphasis on the in-plane shear behavior including the complex internal structure of CLT. Numerical analysis based on 3D-FE models was used and compared with two existing analytical approaches, namely representative volume sub element (method I) and composite beam theory (method II). The separate verification of bending and shear stresses including tree different shear failure modes was performed, and a good agreement was obtained. The main difference between the results relates to shear failure mode in the crossing areas between the orthogonally bonded lamellas in which the distribution of shear stresses tzx over the crossing areas per height of the CLT beam is not in accordance with the analytical assumptions. The presented analyses constitute the first attempt to contribute to the on-going review process of Eurocode 5 with respect to CLT beams loaded-in plane. Currently, regulations on designing these types of beams do not exist, and thus experimental and numerical investigations are planned in the future.
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8 records – page 1 of 1.