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42 records – page 1 of 5.

Acoustic Impact Testing and Waveform Analysis for Damage Detection in Glued Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue771
Year of Publication
2017
Topic
Acoustics and Vibration
Serviceability
Material
Glulam (Glue-Laminated Timber)
Author
Xu, Feng
Wang, Xiping
Teder, Marko
Liu, Yunfei
Publisher
De Gruyter
Year of Publication
2017
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Acoustics and Vibration
Serviceability
Keywords
Decay
Delamination
Damage Detection
Moment Analysis
Wavelet Transform
Acoustic Signals
Research Status
Complete
Series
Holzforschung
Summary
Delamination and decay are common structural defects in old glued laminated timber (glulam) buildings, which, if left undetected, could cause severe structural damage. This paper presents a new damage detection method for glulam inspection based on moment analysis and wavelet transform (WT) of impact acoustic signals. Acoustic signals were collected from a glulam arch section removed from service through impact testing at various locations. The presence and positions of internal defects were preliminarily determined by applying time centroid and frequency centroid of the first moment. Acoustic signals were then decomposed by wavelet packet transform (WPT) and the energy of the sub-bands was calculated as characteristics of the response signals. The sub-bands of 0–375 Hz and 375–750 Hz were identified as the most discriminative features that are associated with decay and delamination and therefore are indicative of the presence of delamination or decay defects. A defect diagnosis algorithm was tested for its ability to identify internal decay and delamination in glulam. The results show that depth of delamination in a glulam member can be determined with reasonable accuracy.
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Adhesive Bonding of Structural Hardwood Elements

https://research.thinkwood.com/en/permalink/catalogue75
Year of Publication
2015
Topic
Mechanical Properties
Serviceability
Moisture
Material
Glulam (Glue-Laminated Timber)
CLT (Cross-Laminated Timber)
Author
Hassani, Mohammad
Organization
ETH Zurich
Year of Publication
2015
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Serviceability
Moisture
Keywords
Abaqus
Adhesives
Beech
Bonding
Delamination
Finite Element Model
Fracture
Long-term
Model
Hardwood
Research Status
Complete
Summary
The current research investigated the delamination process of adhesively bonded hardwood (European beech) elements subject to changing climatic conditions. For the study of the long-term fracture mechanical behavior of gluedlaminated components under varying moisture content, the role of moisture development, time- and moisture-dependent responses are absolutely crucial. For this purpose, a 3D orthotropic hygro-elastic, plastic, visco-elastic, mechano-sorptive wood constitutive model with moisture-dependent material constants was presented in this work. Such a comprehensive material model is capable to capture the true historydependent stress states and deformations which are essential to achieve reliable design of timber structures. Besides the solid wood substrates, the adhesive material also influences the interface performance considerably. Hence, to gain further insight into the stresses and deformations generated in the bond-line, a general hygro-elastic, plastic, visco-elastic creep material model for adhesive was introduced as well. The associated numerical algorithms developed on the basis of additive decomposition of the total strain were formulated and implemented within the Abaqus Finite Element (FE) package. Functionality and performance of the proposed approach were evaluated by performing multiple verification simulations of wood components, under different combinations of mechanical loading and moisture variation. Moreover, the generality and efficiency of the presented approach was further demonstrated by conducting an application example of a hybrid wood element.
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Air-Coupled Ultrasound Propagation and Novel Non-Destructive Bonding Quality Assessment of Timber Composites

https://research.thinkwood.com/en/permalink/catalogue13
Year of Publication
2012
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Martín, Sergio
Organization
ETH Zurich
Year of Publication
2012
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Adhesives
Bonding
Delamination
Failure
Non-Destructive Testing
Air-coupled Ultrasound (ACU)
Finite-Difference Time-Domain (FDTD) model
Research Status
Complete
Summary
Glued laminated timber (glulam) is manufactured by gluing and stacking timber lamellas, which are sawn and finger-jointed parallel to the wood grain direction. This results in a sustainable and competitive construction material in terms of dimensional versatility and load-carrying capacity. With the proliferation of glued timber constructions, there is an increasing concern about safety problems related to adhesive bonding. Delaminations are caused by manufacturing errors and in service climate variations simultaneously combined with long-sustained loads (snow, wind and gravel filling on flat roofs). Several recent building collapses were related to bonding failure, which should be prevented in the future with a timely defect detection. As an outlook, the feasibility of air-coupled ultrasound tomography was demonstrated with numerical tests and preliminary experiments on glulam. The FDTD wave propagation model was excited by the difference of the time-reversed sound fields transmitted through a test and a reference (defect-free) glulam cross-section. Both datasets were obtained with the same SLT setup. Wave convergences then provided a map of bonding defects along the height and width of the inspected glulam cross-sections. Further research is envisaged in this direction
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Applicability of Various Wood Species in Glued Laminated Timber - Parameter Study on Delamination Resistance and Shear Strength

https://research.thinkwood.com/en/permalink/catalogue592
Year of Publication
2014
Topic
Mechanical Properties
Connections
Material
Glulam (Glue-Laminated Timber)
Author
Jiang, Yuan
Schaffrath, Jörg
Knorz, Markus
Winter, Stefan
Van de Kuilen, Jan-Willem
Year of Publication
2014
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
Hardwood
Softwood
Gluability
Delamination
Shear Strength
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
In a current research project the gluability of various soft- und hardwood species and their applicability in glued laminated timber are investigated. The influence of the processing parameters on the delamination resistance and shear strength of the glue lines are presented in this work. The bonding forces, which are necessary for the integrity of a glue line, act in the interface within a distance that varies from nanometers to micrometers. The parameters that may have significant influence on the bonding strength and durability of adhesive joints are numerous and depend on the type of wood, adhesive and processing conditions.
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Bending and Bonding Properties of Mixed-Species Glued Laminated Timber from Merpauh, Jelutong and Sesendok

https://research.thinkwood.com/en/permalink/catalogue2434
Year of Publication
2019
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Wood Building Systems
Author
Mohamad, Wan Hazira Wan
Bhkari, Norshariza Mohamad
Ahmad, Zakiah
Organization
Universiti Teknologi MARA Malaysia
Publisher
Universiti Teknologi Malaysia
Year of Publication
2019
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Wood Building Systems
Topic
Mechanical Properties
Keywords
Bending Properties
Delamination
Mixed-Species
Bonding Properties
Shear Glue Line
Research Status
Complete
Series
Jurnal Teknologi
Summary
This study investigates the bending and bonding performances of glued laminated timber beams manufactured using a combination of Malaysian lower and higher- grade timber species. Two types of beams were prepared which were mono-species and mixed-species glulam. Mono-species glulam with uniform layup were fabricated using Merpauh, Jelutong and Sesendok. Mixed-species glulam with balanced layup were fabricated whereby Merpauh was positioned equally at the outer layers and either Jelutong or Sesendok were positioned at the inner layers. Three replicates of ten-layered glulam beams measuring 100 mm in width, 300 mm in depth and 6200 mm in length were manufactured according to MS758 for each mono and mixed-species glulam. Bending, delamination and block shear tests were done on all the glulam beams. The results show that glulam manufactured from the combination of Sesendok and Merpauh obtained the highest bending properties and structural efficiency. In addition, the bonding performance at the interface between Sesendok-Merpauh lamellas proved to be excellent.
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Block Shear Strength and Delamination of Cross-Laminated Timber Fabricated with Japanese Larch

https://research.thinkwood.com/en/permalink/catalogue1220
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Gong, Yingchun
Wu, Guofang
Ren, Haiqing
Publisher
North Carolina State University
Year of Publication
2016
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Larch
Delamination
Block Shear Strength
Temperature
One-Component Polyurethane
Research Status
Complete
Series
BioResources
Summary
Process parameters of cross-laminated timber (CLT) fabricated with Japanese larch were evaluated. The process parameters were designed by using an orthogonal test including pressure, glue consumption, and adhesive. Both delamination and block shear tests were conducted on CLT in accordance with GB/T 26899 (2011). The results showed that the optimum process parameters were A2B3C2 including pressure (1.2 MPa), glue consumption (200g/m2), and amount of sdhesive (one-component plyurethane). The weight loss and moisture absoption increased when the temperature increased, but the block shear strength decreased as the temperature was raised from 20C to 230C.
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Butt-Joint Bonding of Timber as a Key Technology for Point-Supported, Biaxial Load Bearing Flat Slabs Made of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2466
Year of Publication
2019
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Author
Zöllig, Stefan
Muster, Marcel
Themessl, Adam
Publisher
IOP Publishing Ltd
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
Butt-Joint
Bending Strength
Shear Resistance
Research Status
Complete
Series
IOP Conference Series: Earth and Environmental Science
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Free
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Charring Behavior of Structural Timber Elements in Full-Scale Fire Tests of Three Story Timber School Buildings

https://research.thinkwood.com/en/permalink/catalogue1706
Year of Publication
2016
Topic
Fire
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Suzuki, Jun-ichi
Kaku, Chihiro
Naruse, Tomohiro
Kagiya, Koji
Noboru, Yasui
Itagaki, Naoyuki
Izumi, Jun-ichi
Seki, Mariko
Kaku, Teruhiko
Hasemi, Yuji
Year of Publication
2016
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Fire
Keywords
Charring Rate
Delamination
Full Scale
Fire Test
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4437-4446
Summary
The charring behavior of timber structural elements, such as the charring rate of timber elements and delamination of glue-laminated timber, affects the structural stability of timber buildings. The charring rate of timber elements varies depending on the severity of fire exposure. However, charring rates have been ordinarily investigated in fire tests under the standard fire exposure defined by ISO 834. It is important to accumulate and analyze data on the charring behavior of timber elements under actual fire exposure. The aim of this study was to clarify the charring behavior of glue-laminated timber structural elements exposed to actual fire in full-scale fire tests of three-story timber school buildings. Charred and uncharred areas of the timber structural elements were carefully observed and investigated after the fire tests. The charring rates of timber elements in full-scale fire tests ranged from 0.6 mm/min to 1.3mm/min. The charring rates were greater than the nominal charring rates reported in past studies because of preheating and severe fire exposure.
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Comparison of Newly Proposed Test Methods to Evaluate the Bonding Quality of Cross-Laminated Timber (CLT) Panels by Means of Experimental Data and Finite Element (FE) Analysis

https://research.thinkwood.com/en/permalink/catalogue1360
Year of Publication
2016
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Author
Betti, Michele
Brunetti, Michele
Lauriola, Marco
Nocetti, Michela
Ravalli, Francesco
Pizzo, Benedetto
Publisher
ScienceDirect
Year of Publication
2016
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
Shear Test
Bonding Quality
Delamination
Research Status
Complete
Series
Construction and Building Materials
Summary
The effectiveness of new shear test methods for evaluating the face-bonding quality of Cross-Laminated Timber (CLT) panels was examined by comparing experimental data and numerical modelling. The common characteristic of the specimens was the loading with angle of 45 with respect to the wood grain, in order to avoid rolling shear during test. In addition, the sampling methodology along the panel was investigated, as well as the relation between shear and delamination tests, and the possibility of coupling them using the same specimen. The results demonstrated that all the proposed shear test methods were effective for evaluating the quality of bonding among layers in CLT panels; however, the practical applicability of the methods led to elect the most suitable for inclusion in technical standards. Shear and delamination results proved not to be correlated, and the results showed that the size of the specimen is a crucial factor in determining the outcomes of delamination tests. Therefore, while it is feasible to propose the coupling of accelerated aging procedures with shear tests, the size of the samples need to be higher than the one tested here.
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Comparison of Test Methods for the Determination of Delamination in Glued Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2428
Year of Publication
2019
Topic
Design and Systems
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems

42 records – page 1 of 5.