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Non Destructive Evaluation of Elastic Material Properties of Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue2315
Year of Publication
2008
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Steiger, René
Gülzow, Arne
Gsell, D.
Year of Publication
2008
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Panels
Elastic Properties
Full Scale
Experimental Modal Analysis
Conference
COST Workshop – Highly Performing Timber Structures: Reliability, Assessment, Monitoring and Strengthening
Research Status
Complete
Summary
Cross-laminated timber (CLT) is a panel-shaped engineered wood product, assembled of layers of lamellas (mostly softwood) with perpendicular orientation of the grain direction. In contrast to other panel-shaped engineered wood products, CLT is not used as components of structural elements, but rather as load bearing plates and shear panels. The design of CLT used as load-bearing plates is often governed by serviceability criterions like maximal deflection and vibration susceptibility. Hence, predicting the respective behaviour of such panels requires accurate information about their elastic properties. With the aim of determining the global elastic properties of full-scale CLT panels directly in the production line, a fully automatic, non-destructive procedure based on experimental and theoretical modal analysis was developed: Resonance frequencies and mode-shapes of the plates are determined first by means of an experimental modal analysis. A simulation model based on Reddy's higher order plate theory is then used to analytically calculate natural frequencies and mode shapes as functions of the unknown elastic parameters. Finally, in an optimization process two in plane moduli of elasticity and three shear moduli can be identified by minimizing the differences between measured and analytically estimated resonance frequencies. First, the method was investigated in the laboratory. The applicability of the method was then proven on 42 CLT panels with different dimensions, layer sizes and from different producers, and validated by static bending experiments on full-scale panels and panel-bars. Finally the procedure was optimized for the application in the production line.
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Prediction of Dynamic Response of a 7-Storey Massive XLam Wooden Building Tested on a Shaking Table

https://research.thinkwood.com/en/permalink/catalogue1885
Year of Publication
2010
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Author
Dujic, Bruno
Žarnic, Roko
Pirmanšek, Klara
Ceccotti, Ario
Year of Publication
2010
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Seismic
Keywords
Multi-Storey
Full Scale Test
Blind Prediction
Static Analyses
Stiffness
Load Bearing
Mechanical Connectors
Dynamic Analysis
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
June 20-24, 2010, Riva del Garda, Italy
Summary
In October 2007 a series of seismic tests were carried out on a 7-storey building made of cross laminated (XLam) wooden panels in natural scale on a shaking table E-Defence in Japan within the SOFIE project. The paper presents calculation procedure, prediction of dynamic behaviour of the tested structure excited by the earthquake record "Kobe JMA 1995" and comparison between predicted, that means calculated and measured response. Due to blind prediction approach some construction details were not known before dynamic time history response calculation. Therefore some assumptions, engineering judgment and rough static analyses were needed to define all construction parts which were in modelling approach assumed as important and could have had influence on dynamic response of the analyzed structure. The most important assumptions related to the definition of the stiffness and load bearing capacity of mechanical connections, types of anchors and their positions in each floor level, were determined on the basis of static analysis where the structure was loaded with equivalent horizontal seismic forces and then were used in dynamic analysis. A mathematical model was developed in program SAP2000 where modal and time history analyses were carried out. Comparison of calculated and measured results is described and evaluated on the basis of the model assumptions and its simplification.
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Displacement-Based Seismic Design of Timber Structures

https://research.thinkwood.com/en/permalink/catalogue1891
Year of Publication
2011
Topic
Design and Systems
Seismic
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Other Materials
Application
Wood Building Systems
Walls
Floors
Beams
Columns
Frames
Author
Loss, Cristiano
Publisher
University of Trento
Year of Publication
2011
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Other Materials
Application
Wood Building Systems
Walls
Floors
Beams
Columns
Frames
Topic
Design and Systems
Seismic
Keywords
Direct Displacement-Based Design
Direct-DBD
Full-Scale
Single Family Houses
Multi-Storey
Connections
Research Status
Complete
Notes
Doctoral Thesis (PhD)
Summary
The research is aimed at developing seismic methods for the design and evaluation of the seismic vulnerability of wooden structures, using a displacement-based approach. After a brief introduction on the seismic behaviour of timber structures, the general Direct Displacement-Based Design (Direct-DBD) procedure and the state-of-the-art are presented, with clear reference to the application of the Direct-DBD method to wooden buildings. The strength of the Direct-DBD method is its ability to design structures in a manner consistent with the level of damage expected, by directly relating the response and the expected performance of the structure. The research begins with a description of the procedural aspects of the Direct-DBD method and the parameters required for its application. The research presented focuses on the formulation of a displacement-based seismic design procedure, applicable to one-storey wooden structures made with a portal system. This typology is very common in Europe and particularly in Italy. A series of analytical expressions have been developed to calculate design parameters. The required analytical Direct-DBD parameters are implemented based on the mechanical behaviour of the connections, made with metal dowel-type fasteners. The calibration and subsequent validation of design parameters use a Monte Carlo numerical simulation and outcomes obtained by tests in full-scale. After the description of the Displacement-Based method for one-storey wooden structures, a series of guidelines to extend the Direct-DBD methodology to other types and categories of timber systems are proposed. The thesis presents the case of a multi-storey wood frame construction, which is a simple extension of the glulam portal frame system. Part of this work has been done within the RELUIS Project, (REte dei Laboratori Universitari di Ingegneria Sismica), Research Line IV, which in the years between 2005 and 2008 involved several Italian universities and Italian institutes of research in the development of new seismic design methods. The Project produced the first draft of model code for the seismic design of structures based on displacement (Direct-DBD). This thesis is the background to the section of the model code developed for timber structures.
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Predicting the Fire Resistance of Cross-Laminated Timber Assemblies

https://research.thinkwood.com/en/permalink/catalogue1865
Year of Publication
2012
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Walls
Wood Building Systems
Author
Craft, Steven
Desjardins, Richard
Bénichou, Noureddine
Organization
National Research Council of Canada
Publisher
National Research Council Canada. Construction
Year of Publication
2012
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Walls
Wood Building Systems
Topic
Fire
Keywords
Fire Resistance
Assembly
Panels
Full-Scale Fire Test
Full-Scale
Research Status
Complete
Summary
There is growing interest from the Canadian wood products industry to produce and use cross-laminated timber (CLT) panels in construction. Because this is a new product in North America, there is a need to demonstrate that the product meets various performance attributes such as structural resistance, sound transmission and fire resistance. This research aims to address two primary objectives which will support the North American adoption of CLT. First, a generic calculation method for determining the fire-resistance of CLT assemblies is needed to enable producers to manufacture a number of different configurations of panels without the need to run a large number of full-scale fire tests. Second, the CLT assemblies chosen for testing have been identified as the most likely configurations to be used thereby providing test data to support the claims of fire-resistance to help satisfy the authority having jurisdiction.
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Design of Post-Tensioned Timber Beams for Fire Resistance

https://research.thinkwood.com/en/permalink/catalogue4
Year of Publication
2012
Topic
Design and Systems
Fire
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Buchanan, Andrew
Abu, Anthony
Carradine, David
Moss, Peter
Spellman, Phillip
Year of Publication
2012
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Design and Systems
Fire
Keywords
Full Scale
Furnace Tests
Post-Tensioned
Box Beams
Vertical Loads
Failure
Conference
International Conference on Structures in Fire
Research Status
Complete
Notes
June 6-8, 2012, Zurich, Switzerland
Summary
This paper describes a series of three full-scale furnace tests on post-tensioned LVL box beams loaded with vertical loads, and presents a proposed fire design method for post-tensioned timber members. The design method is adapted from the calculation methods given in Eurocode 5 and NZS:3603 which includes the effects of changing geometry and several failure mechanisms specific to post-tensioned timber. The design procedures include an estimation of the heating of the tendons within the timber cavities, and relaxation of post-tensioning forces. Additionally, comparisons of the designs and assumptions used in the proposed fire design method and the results of the full-scale furnace tests are made. The experimental investigation and development of a design method have shown several areas which need to be addressed. It is important to calculate shear stresses in the timber section, as shear is much more likely to govern compared to solid timber. The investigation has shown that whilst tensile failures are less likely to govern the fire design of post-tensioned timber members, due to the axial compression of the post-tensioning, tensile stresses must still be calculated due to the changing centroid of the members as the fire progresses. Research has also highlighted the importance of monitoring additional deflections and moments caused by the high level of axial loads.
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Experimental-Numerical Analyses of the Seismic Behaviour of Cross-Laminated Wall Systems

https://research.thinkwood.com/en/permalink/catalogue56
Year of Publication
2012
Topic
Seismic
Energy Performance
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Gavric, Igor
Rinaldin, Giovanni
Amadio, Claudio
Fragiacomo, Massimo
Ceccotti, Ario
Year of Publication
2012
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Seismic
Energy Performance
Keywords
Finite Element Model
Abaqus
Experimental
Numerical
Full Scale
Cyclic Testing
Conference
World Conference on Earthquake Engineering
Research Status
Complete
Notes
September 24-28, 2012, Lisbon, Portugal
Summary
The paper discusses experimental and numerical seismic analyses of typical connections and wall systems used in cross-laminated (X-Lam) timber buildings. An extended experimental programme on typical X-Lam connections was performed at IVALSA Trees and Timber Institute. In addition, cyclic tests were also carried out on full-scale single and coupled X-Lam wall panels with different configurations and mechanical connectors subjected to lateral force. An advanced non-linear hysteretic spring to describe accurately the cyclic behaviour of connections was implemented in ABAQUS finite element software package as an external subroutine. The FE model with the springs calibrated on single connection tests was then used to reproduce numerically the behaviour of X-Lam wall panels, and the results were compared with the outcomes of experimental full-scale tests carried out at IVALSA. The developed model is suitable for evaluating dissipated energy and seismic vulnerability of X-Lam structures.
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Experimental and Analytical Investigation of Short-Term Behaviour of LVL–Concrete Composite Connections And Beams

https://research.thinkwood.com/en/permalink/catalogue150
Year of Publication
2012
Topic
Connections
Design and Systems
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Beams
Author
Khorsandnia, Nima
Valipour, Hamid
Crews, Keith
Publisher
ScienceDirect
Year of Publication
2012
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Beams
Topic
Connections
Design and Systems
Mechanical Properties
Keywords
Four Point Bending Test
Screws
Load Deflection
Model
Full Scale
Research Status
Complete
Series
Construction and Building Materials
Summary
This paper reports the results of experimental push-out tests on three different types of timber–concrete composite (TCC) connections, including normal screw, SFS and bird-mouth. The load-slip diagrams obtained from lab tests are employed to calculate the slip modulus of the connections for serviceability, ultimate and near collapse cases based on Eurocode 5 recommendations. Additionally, four full-scale TCC beams with normal screw, SFS and bird-mouth are constructed and tested under four-point bending within the serviceability load range to verify the slip modulus of connections which derived from the push-out tests. Further, based on the experimental results and using nonlinear regression, an analytical model each one of the connections is derived which can be easily incorporated into nonlinear FE analyses of TCC beams.
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The Fire Performance of Post-Tensioned Timber Beams

https://research.thinkwood.com/en/permalink/catalogue159
Year of Publication
2012
Topic
Fire
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Spellman, Phillip
Organization
University of Canterbury
Year of Publication
2012
Format
Thesis
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Fire
Keywords
Failure Mechanisms
Full Scale
Post-Tensioning
Steel Tendons
Fire Resistance
Box Beams
Research Status
Complete
Summary
The focus of this research was to investigate the fire performance of post-tensioned timber beams. This was completed through a series of full-scale furnace tests, and the development of a fire resistance design method. Previous research has focused on the seismic performance and gravity frame performance of post-tensioned timber, both of which yielded promising results. There is however a commonly perceived increase in fire risk with timber building, particularly multi-storey timber buildings, and the fire performance of post-tensioned timber had not previously been investigated.
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Modelling the Fire Performance of Structural Timber Floors

https://research.thinkwood.com/en/permalink/catalogue212
Year of Publication
2012
Topic
Design and Systems
Fire
Material
Timber-Concrete Composite
Application
Floors
Author
O'Neill, James
Abu, Anthony
Carradine, David
Moss, Peter
Buchanan, Andrew
Year of Publication
2012
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Design and Systems
Fire
Keywords
Failure Mechanisms
Finite Element Model
Fire Resistance
Thermo-mechanical
Full Scale
Conference
International Conference on Structures in Fire
Research Status
Complete
Notes
June 6-8, 2012, Zurich, Switzerland
Summary
This paper describes numerical modelling to predict the fire resistance of engineered timber floor systems. The floor systems under investigation are timber composite floors (various timber joist and box floor cross sections), and timber-concrete composite floors. The paper describes 3D numerical modelling of the floor systems using finite element software, carried out as a sequential thermo-mechanical analysis. Experimental testing of these floor assemblies is also being undertaken to calibrate and validate the models, with a number of full scale tests to determine the failure mechanisms for each floor type and assess fire damage to the respective system components. The final outcome of this research will be simplified design methods for calculating the fire resistance of a wide range of engineered timber floor systems.
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Design and Behavior of a Mid-Rise Cross-Laminated Timber Building

https://research.thinkwood.com/en/permalink/catalogue242
Year of Publication
2012
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Lenon, Conor
Organization
Colorado School of Mines
Year of Publication
2012
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Keywords
Finite Element Model
Shake Table Test
Full Scale
Moment Resistance
Research Status
Complete
Summary
Cross-Laminated Timber (CLT) is a new engineered wood material that was introduced in the past decade as a promising candidate to build structures over 10 stories. So far, a handful of tall CLT buildings have been built in low seismic regions around the world. Full-scaled seismic shaking table tests revealed the vulnerability of this building type when resisting seismically-induced overturning. This study proposes a new analysis and design approach for developing overturning resistance for platform CLT buildings. New structural detailing is proposed to alter the moment-resisting mechanism and enable coupled action through the floor system. The method is applied to the design of a 12-story CLT building, which was evaluated numerically to assess the conservativeness of the design through system level finite element model simulations.
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66 records – page 1 of 7.