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14 records – page 1 of 2.

Cross Laminated Timber Reinforced with Carbon Fibre

https://research.thinkwood.com/en/permalink/catalogue2661
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Cao, Xinlei
Organization
University of Alberta
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Carbon Fiber
Flexural Stiffness
Stress Distribution
Analytical Model
Finite Element Method (FEM)
Research Status
In Progress
Summary
Although engineered wood products such as glued laminated timber (glulam) and cross-laminated timber (CLT) have successfully eliminated the flaws inherently exist in conventional wood products, they are still not comparable with steel and concrete in terms of strength and stiffness. Among all different options for reinforcement, Carbon Fibre is relatively popular due to its high tensile strength, low weight, and easy installation. This study presents an analysis of flexural stiffness and stress distributions of CLT panels reinforced with carbon fibre mats, based on an analytical method and finite element method (FEM).
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Design Methods of Elements from Cross-Laminated Timber Subjected to Flexure

https://research.thinkwood.com/en/permalink/catalogue189
Year of Publication
2015
Topic
Design and Systems
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Vilguts, Aivars
Serdjuks, Dmitrijs
Pakrastins, Leonids
Publisher
ScienceDirect
Year of Publication
2015
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Design and Systems
Mechanical Properties
Keywords
Finite Element Method (FEM)
Static Loading Test
Stress
Research Status
Complete
Series
Procedia Engineering
Summary
Design methods of cross-laminated timber elements subjected to bending is considered. The methods are based on LVS EN 1995–1–1. The presented methods were checked by the experiment and analytically. Two cross-laminated timber plates with the total thickness of 95 mm were tested under action of static load. The considered cross-laminated timber plates were analysed by FEM method, which is based on the using of computational program ANSYSv14. The comparison of stresses acting in the edge fibres of the plate and the maximum vertical displacements shows that the considered methods can be used for engineering calculations so as the difference between the experimentally and analytically obtained results does not exceed 20%.
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Dynamic Response of Cross Laminated Timber Floors Subject to Internal Loads

https://research.thinkwood.com/en/permalink/catalogue2716
Year of Publication
2020
Topic
Design and Systems
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Skoglund, Jacob
Publisher
Lund University
Year of Publication
2020
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Design and Systems
Mechanical Properties
Keywords
Internal Loads
Finite Element Method (FEM)
Panels
Seven-Layer Model
Modal Analysis
3D Model
2D Model
Research Status
Complete
Summary
The deregulation of timber for use in large scale constructions has seen the addition of new innovative timber-based products to a category of products referred to as engineered wood products. A now well established addition to these products is cross laminated timber, or CLT for short. CLT products use a form of orthogonal layering, where several parallel wooden boards are arranged in a number of layers, each layer being orthogonal to the previous. The use of orthogonal layering allows for increased stiffness in the two plane directions, resulting in a lightweight construction product with high load bearing capacity and stiffness. To evaluate the dynamic behaviour of structures, engineers commonly apply the finite element method, where a system of equations are solved numerically. Given a sufficient amount of computational power and time, the finite element method can help to solve most dynamical problems. For sufficiently large or complex structures the amount of resources needed may be outside the scope of possibility or feasibility for many. Therefore, evaluating the usage of certain design simplifications, such as omitting to models aspects of the geometry, or alternative forms of analysis for CLT panels may help to reduce the time and resources required for an analysis. In this Master's dissertation, a seven-layer CLT-panel has been created. In the model, each individual board and the gaps between the boards are modelled. The seven-layer model is used as a reference to evaluate the possibility of using less detailed alternative models. The alternative models are created as a layered 3D model and a composite 2D model, both models omit the modelling of the individual laminations, resulting in the layers being solid. The results show small errors for the alternative models when using modal analysis. Concluding that the modal behaviour and dynamic response of a CLT panel can be evaluated using a composite 2D model or a less-detailed layered 3D model. This significantly reduces the amount of time and computational power needed for an analysis, and clearly indicates the benefit of using alternative less detailed models.
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Effect of Layer Arrangement on Bending Strength of Cross-Laminated Timber (CLT) Manufactured from Poplar (Populus deltoides L.)

https://research.thinkwood.com/en/permalink/catalogue3019
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Haftkhani, Akbar Rostampour
Hematabadi, Hojat
Organization
University of Mohaghegh Ardabili
University of Technical & Vocational
Editor
Zhou, Binzhong
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Poplar
Bending Properties
Layer Configuration
Shear Analogy Method
Finite Element Method (FEM)
Research Status
Complete
Series
Buildings
Summary
This study aimed to investigate the effect of layer arrangement on bending properties of CLT panels made from poplar (Populus deltoides L.). A total of 20 three-layer CLT panels with the same dimensions of 1300 × 360 × 48 mm3 (Length, Width, Thickness) were fabricated in five configurations: 0/30/0, 0/45/0, 0/90/0, 45/0/45, and 45/45/45. The apparent modulus of elasticity (MOEapp), modulus of rupture (MOR) and apparent bending stiffness (EIapp) values in major and minor axes of CLT panels were calculated using experimental bending testing. In the major axis, the highest values of MOR, MOEapp, and EIapp were obtained from the 0/30/0 arrangement, while the least values resulted from the arrangements of 90/60/90 and 90/45/90 in the minor axis. Besides, in all arrangements, the average of the experimental apparent bending stiffness values (EIapp,exp) of specimens was higher than that of the shear analogy apparent bending stiffness values (EIapp,shear). The bending and shear stress distribution values over the cross section of samples were also estimated using the finite element method. Moreover, the numerical apparent bending stiffness (EIapp,fem) values of samples were compared to experimental apparent bending stiffness (EIapp,exp) values. Based on experimental and finite element method results, in all groups of layer arrangements, the EIapp,fem values concurred well with the EIapp,exp values.
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Evaluating Timoshenko Method for Analyzing CLT under Out-of-Plane Loading

https://research.thinkwood.com/en/permalink/catalogue2836
Year of Publication
2020
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Ceilings
Decking
Floors
Walls
Author
Rahman, MD Tanvir
Ashraf, Mahmum
Ghabraie, Kazem
Subhani, Mahbube
Organization
Deakin University
Publisher
MDPI
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Ceilings
Decking
Floors
Walls
Topic
Mechanical Properties
Keywords
Rolling Shear
Shear Deformation
Timoshenko Theory of Bending
Shear Stiffness
Finite Element Method (FEM)
Research Status
Complete
Series
Buildings
Summary
Cross-laminated timber (CLT) is an engineered wood product made up of layers of structurally graded timber, where subsequent layers are oriented orthogonally to each other. In CLT, the layers oriented in transverse direction, generally termed as cross-layer, are subjected to shear in radial–tangential plane, which is commonly known as rolling shear. As the shear modulus of cross-layers is significantly lower than that in other planes, CLT exhibits higher shear deformation under out-of-plane loading in contrast to other engineered wood products such as laminated veneer lumber (LVL) and glue laminated timber (GLT). Several analytical methods such as Timoshenko, modified gamma and shear analogy methods were proposed to account for this excessive shear deformation in CLT. This paper focuses on the effectiveness of Timoshenko method in hybrid CLT, in which hardwood cross-layers are used due to their higher rolling shear modulus. A comprehensive numerical study was conducted and obtained results were carefully analyzed for a range of hybrid combinations. It was observed that Timoshenko method could not accurately predict the shear response of CLTs with hardwood cross layers. Comprehensive parametric analysis was conducted to generate reliable numerical results, which were subsequently used to propose modified design equations for hybrid CLTs.
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Evaluation and Optimization of the Vibration Behavior of CLT-Concrete Floors

https://research.thinkwood.com/en/permalink/catalogue2673
Topic
Acoustics and Vibration
Material
Timber-Concrete Composite
CLT (Cross-Laminated Timber)
Application
Floors
Organization
Université Laval
Material
Timber-Concrete Composite
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Finite Element Method (FEM)
Vibration Performance
Creep
Displacement
Natural Frequency
Research Status
In Progress
Notes
Project contact is Sylvain Ménard at Université Laval
Summary
Designers of large buildings generally want floor systems with large spans (9 m). These floors are often sized by the requirement of vibratory performance and, correlatively, deflection. The composite wood-concrete floors allow large spans with reduced static height. They are a promising alternative to simple concrete slabs. Objective 1 - Determine the evolution of the natural frequency of the CLT-concrete composite floor as a function of the stiffness of the connector, and correlate the experimental results with the model by the finite element method. Objective 2 - Parametric study of the vibration performance of the CLT-concrete composite floor. The impact of several parameters on the dynamic performance of the floor will be determined, especially the characteristics of the constituent materials, connector and the creep of the floor. Objective 3 - Build the metamodels for the study of multi-objective optimization optimization of a wood-concrete composite floor solution in relation to a regional problem in Aquitaine.
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Finite-Element-Based Prediction of Moisture-Induced Crack Patterns for Cross Sections of Solid Wood and Glued Laminated Timber Exposed to a Realistic Climate Condition

https://research.thinkwood.com/en/permalink/catalogue2764
Year of Publication
2021
Topic
Moisture
Serviceability
Material
Glulam (Glue-Laminated Timber)
Author
Autengruber, Maximilian
Lukacevic, Markus
Gröstlinger, Christof
Füssl, Josef
Publisher
ScienceDirect
Year of Publication
2021
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Moisture
Serviceability
Keywords
Eurocode 5
Finite Element Simulation
Finite Element Method (FEM)
Failure
Cracks
Load Bearing Capacity
Research Status
Complete
Series
Construction and Building Materials
Summary
Moisture may significantly influence the dimensions and behavior of wooden elements and, thus, it is important to consider within both serviceability as well as ultimate limit state designs. Dimensional changes, also called swelling (during wetting) and shrinkage (during drying), are non-uniform due to the direction-dependent expansion coefficients of wood and usually lead to eigenstresses. If these exceed certain strength values, cracking may occur, which reduces the resistance to external loads, especially to shear stresses. The current standard Eurocode 5 takes these circumstances very simplified into account, by so-called service classes, defined based on the surrounding climate and average moisture levels over the course of a year. Accordingly, reduction factors for strength values and cross section widths are assigned. For a better understanding of the climate-induced changes in wooden beams, we exposed 18 different beams with varying cross sections to a representative climate of Linz, Austria, within the framework of a finite element simulation and investigated the resulting moisture fields and crack patterns. For this purpose, expansions and linear-elastic stresses were simulated by using the thermal and moisture fields obtained in the first simulation step and expansion coefficients. Using a multisurface failure criterion, two critical points in time were determined for each cross section, at which advanced crack simulations were carried out using the extended finite element method. The resulting crack lengths showed that the Eurocode 5 assumption of a linear relationship between crack-free and total width could be verified for both drying and wetting cases. In future, the obtained crack patterns might also be used to investigate the actual reduction of load-bearing capacities of such cross sections, since the position of a crack and, for example, the maximum shear stress may not coincide. For the first time in this work, a consistent concept is presented to estimate the resulting crack formation in a wooden element from any moisture load based on a mechanical well-founded simulation concept. For this reason, this work is intended to lay a basis for a more accurate consideration of climate-related loads on wooden elements up to timber constructions.
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Improved low-frequency performance of cross-laminated timber floor panels by informed material selection

https://research.thinkwood.com/en/permalink/catalogue2961
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Persson, Peter
Flodén, Ola
Danielsson, Henrik
Peplow, Andrew
Andersen, Lars Vabbersgaard
Organization
Lund University
Aarhus University
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Vibroacoustic Response
Floor Vibration
Wood Species
Strength Class
Finite Element Method (FEM)
Research Status
Complete
Series
Applied Acoustics
Summary
The paper demonstrates improved structural low-frequency vibroacoustic performance of cross-laminated timber (CLT) floor panels by informed selection of the wood material. The use of wood species and strength classes that are not traditionally assigned to CLT panels was investigated in order to study their influence on dynamic characteristics and vibroacoustic response metrics. The potential of each of the orthotropic material properties to alternate the vibration response was examined to determine the governing parameters of the low-frequency vibroacoustic performance. The effects on transfer mobility response functions, and eigenfrequencies and mode shapes were used for a rigorous performance study of the panels. It was found that using laminations with stiffness properties typical for hardwoods ash, beech, and birch can significantly improve the performance of a CLT floor panel, and they outperform laminations of typical softwood strength classes.
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A Novel LVL- Based Internal Reinforcement for Holes in Glulam Beams

https://research.thinkwood.com/en/permalink/catalogue1908
Year of Publication
2018
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Tapia, Cristóbal
Aicher, Simon
Year of Publication
2018
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Mechanical Properties
Keywords
Hybrid Build Up
Parametric Study
Finite Element Method (FEM)
Reinforcement
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 20-23,2018. Seoul, Republic of Korea
Summary
A newly developed reinforcement system for glulam, actually representing a new generic wood com-pund, is presented. The composite consists on a hybrid cross-section, composed of intercalated layers of GLT and LVL, glued together along the width-direction of the beam. The specific build-up improves in first instance the mechanical properties of the glulam in the direction perpendicular to the grain significantly. Hence, the composite is especially well suited for the reinforcement of arrays of large holes in wide cross-sections. Secondly, the layers were tailored in such a manner, that the bending load capacity equalls that of the gross-cross-section. A parametric study was performed by means of the finite element method, to study the redistribution of stresses perpendicular to the main axis of the beam in the region of stress concentrations at one of the hole corners. Specifically, the load sharing of the vertical tensile force F_t,90 described in the German National Annex to EC5 was analyzed, and an analytical relationship depending on the thickness, elastic modulus and moment-to-shear-force ratio was developed.
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Free
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Numerical Study of Cross-Laminated Timber Under Fire

https://research.thinkwood.com/en/permalink/catalogue2440
Year of Publication
2019
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Floors

14 records – page 1 of 2.