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139 records – page 1 of 14.

Behavior of Cross-Laminated Timber Panels Made from Fibre-Managed Eucalyptus nitens under Short-Term Serviceability Loads

https://research.thinkwood.com/en/permalink/catalogue3360
Year of Publication
2023
Topic
Mechanical Properties
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Liang, Yingwei
Taoum, Assaad
Kotlarewski, Nathan
Chan, Andrew
Holloway, Damien
Organization
University of Tasmania
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Serviceability
Keywords
Hardwood CLT
Serviceability Performance
Eucalyptus nitens
Vibration
Deflection
Modulus of Elasticity
Research Status
Complete
Series
Buildings
Summary
In this study, the preliminary serviceability performance of cross-laminated timber (CLT) panels constructed from fibre-managed Eucalyptus nitens (E. nitens) was investigated via bending and vibration tests. Linear four-point bending tests were performed to determine the stiffness and deflection of all CLT panels under serviceability loads. The dynamic response of CLT panels was tested using a basketball and an accelerometer. The fundamental natural frequencies of all tested panels were above the minimum frequency limit (8 Hz) when extrapolated to spans of up to 4.4 m. The configurations of E. nitens CLT panels were based on different modulus of elasticity (MOE) values for each board. Using higher MOE timber boards as the top and bottom layers can significantly increase the serviceability performance of both bending and vibration tests. The same experiments were carried out on two CLT panels made of strength class C24 Spruce-Pine-Fir to compare the serviceability performance of E. nitens CLT. The results demonstrated that E. nitens is a reliable resource for CLT manufacturing, and exhibits better serviceability performance compared to Spruce CLT. This provides more sustainable options for a species traditionally destined for pulp.
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Reduced and test-data correlated FE-models of a large timber truss with dowel-type connections aimed for dynamic analyses at serviceability level

https://research.thinkwood.com/en/permalink/catalogue3004
Year of Publication
2022
Topic
Mechanical Properties
Serviceability
Acoustics and Vibration
Material
Glulam (Glue-Laminated Timber)
Application
Trusses
Author
Landel, Pierre
Linderholt, Andreas
Organization
RISE Research Institutes of Sweden
Linnaeus University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Trusses
Topic
Mechanical Properties
Serviceability
Acoustics and Vibration
Keywords
Tall Timber Structures
Mechanical Connection
Dowel-type Fastener
Wind-induced Vibration
Modal Testing Properties
Connection Stiffness
FE-Model Reduction
Research Status
Complete
Series
Engineering Structures
Summary
The rise of wood buildings in the skylines of cities forces structural dynamic and timber experts to team up to solve one of the new civil-engineering challenges, namely comfort at the higher levels, in light weight buildings, with respect to wind-induced vibrations. Large laminated timber structures with mechanical joints are exposed to turbulent horizontal excitation with most of the wind energy blowing around the lowest resonance frequencies of 50 to 150 m tall buildings. Good knowledge of the spatial distribution of mass, stiffness and damping is needed to predict and mitigate the sway in lighter, flexible buildings. This paper presents vibration tests and reductions of a detailed FE-model of a truss with dowel-type connections leading to models that will be useful for structural engineers. The models also enable further investigations about the parameters of the slotted-in steel plates and dowels connections governing the dynamical response of timber trusses.
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Assessment of Termite and Decay Damage to Mass Timber Elements in AWPA Ground Proximity and Above Ground Field Tests in Southern Mississippi

https://research.thinkwood.com/en/permalink/catalogue3236
Year of Publication
2022
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Mankowski, Mark E.
Shelton, Thomas
Kirker, Grant
Morrell, Jeffrey J.
Organization
Forest Products Laboratory
Year of Publication
2022
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Mass Panel Plywood
Ground Proximity Test
Above Ground Test
Soil Termiticide
Field Test
Durability
Decay
Termite
Conference
Proc. of 118th annual meeting of American Wood Protection Association
Research Status
Complete
Summary
The ability of soil insecticidal drenches or spray-on insecticide/fungicide treatments to protect mass timber elements was assessed using two modified AWPA ground proximity tests established in 2017 and 2019. The 2017 test evaluated 3-ply Douglas-fir cross-laminated timber using a modified AWPA Standard E26 while the 2019 test used a modified AWPA E21 protocol to evaluate 3-ply Douglas-fir or southern pine cross-laminated timber as well as Douglas-fir mass plywood panels. Both tests were installed at the Harrison Experimental Forest (Saucier, Mississippi) and will be assessed for five years. Treatments include an initial soil termiticide drench, spray-on borate at initiation, borate rods at initiation, remedial boron spray treatment two years after installation, and untreated controls. Samples were left undisturbed for one or two years and then rated for degree of termite and fungal damage. Moisture content of the test materials increased greatly over the non-disturbance period. Untreated control samples were attacked by both decay fungi and termites within the first year after test initiation. Soil termiticide treated plots showed no sign of termite attack, but decay was evident on some samples compared to non-soil termiticide treated plots. Samples treated with borates at test initiation showed limited decay or termite attack. The tests will continue to be evaluated for a period of at least 5 years or longer and serve as critical baseline data for field evaluation methods of mass timber in areas of high subterranean termite and decay pressure.
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Improving durability of cross laminated timber (CLT) with borate treatment

https://research.thinkwood.com/en/permalink/catalogue3246
Year of Publication
2022
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Bagheri, Sajad
Alinejad, Mona
Ohno, Katie M.
Hasburgh, Laura E.
Arango, Rachel
Nejad, Mojgan
Organization
Forest Products Laboratory
Publisher
Springer
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Borate
Durability
Flammability
Termite Resistance
Decay Resistance
Spray Treatment
Research Status
Complete
Series
Journal of Wood Science
Summary
Borate solution was used to treat two sets of Douglas-fr wood samples, one by spraying cross-laminated timbers (CLT) and another set by dip-treating wood in solutions at different retentions. A novel model was developed to explain and predict borate uptake based on dip-treatment parameters. Small-scale CLT samples were prepared using commercial emulsion polymer isocyanate (EPI) and polyurethane (PU) adhesive with dip-treated wood. The effect of adhesive and borate retention on CLT samples were evaluated through adhesion, fire, termite, and decay tests. The adhesion strength of wood was statistically unaffected by borate treatment. Statistical analysis showed that both spray- and dip-treated samples had significantly higher termite and decay resistance and fire performance than the untreated boards. Untreated CLT samples bonded with PU showed a considerably higher inherent decay and termite resistance than untreated specimens bonded with EPI adhesive.
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Development of a modified standard termite test for mass timber products

https://research.thinkwood.com/en/permalink/catalogue3252
Year of Publication
2022
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Franca, Tamara S.F.A.
Stokes, Elizabeth C.
Tang, Juliet D.
Organization
Mississippi State University
Forest Products Laboratory
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Subterranean Termites
Laboratory Assay
Wood Durability
Research Status
Complete
Series
Wood and Fiber Science
Summary
US manufacturers are looking to expand the use of cross-laminated timber (CLT) panels into the North American market, including states located in the southeast where termites are important pests. However, there is no current assessment method for determining CLT vulnerability to the highly destructive native termites found in many states across the United States. The impact of damage by these termites is of particularly high interest in areas with suitable climate to their proliferation, such as the southeastern United States. This study evaluated durability of CLT panels and developed a laboratory assay to test susceptibility of this product to termites. Untreated CLT suffered mass losses of up to 5.8% in testing with an average visual rating of 7.2, indicating a moderate to severe attack with 10-30% of the cross section of the product affected by termite intrusion. Recommendations were developed for the inclusion of modifications presented in standardized testing protocols and will be presented to standards organizations. The proposed method may also be applied to evaluate termite resistance of other mass lumber products such as laminated veneer lumber and Glulam.
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A risk-based approach for timber building decay prediction

https://research.thinkwood.com/en/permalink/catalogue3255
Year of Publication
2022
Topic
Serviceability
Application
Wood Building Systems
Author
Gaspari, Andrea
Giongo, Ivan
Piazza, Maurizio
Organization
University of Trento
Publisher
Elsevier
Year of Publication
2022
Format
Conference Paper
Application
Wood Building Systems
Topic
Serviceability
Keywords
Decay Prediction
TSafe Project
Biotic Attack
Conference
ICSI 2021 The 4th International Conference on Structural Integrity
Research Status
Complete
Series
Procedia Structural Integrity
Summary
The durability of timber structures subjected to biotic attacks is becoming of increasing concern due to several recent examples of failures caused by early degradation. Therefore, the design process of a timber building cannot prescind from accounting for the possible degradation due to biotic attack, especially in light of the recent spread of high-rise timber buildings. Furthermore, it is of extreme importance that reliable models to foresee possible sources of degradation in existing buildings are made available so that retrofit interventions can be programmed before it is too late. In the work presented herein, the decay due to fungal attack was predicted through a risk-based approach where decision trees were created to address all the possible scenarios where water or moisture can intrude within the construction details that most affect the durability. These decision trees allow to assign a risk class, defined based on a thorough review of the major European standards addressing timber “use-classes”. The trees also lead to the selection of a proper prediction function for estimating the decay depth, chosen among suitable functions available in the literature. The proposed methodology was applied to selected case studies where a good correlation was found between the decay level detected onsite and the results from the prediction model. To facilitate the application of the methodology to both the design of new durable timber buildings and the assessment of existing timber structures, an ad hoc software tool named TSafe was developed. In the present paper, due to the length limit, the focus is on the decision trees and the risk classes, while just a brief description of the case study used for the procedure validation is given.
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Measured and perceived indoor air quality in three low-energy wooden test buildings

https://research.thinkwood.com/en/permalink/catalogue3281
Year of Publication
2022
Topic
Serviceability
Author
Alapieti, Tuomas
Vornanen-Winqvist, Camilla
Mikkola, Raimo
Salonen, Heidi
Organization
Queensland University
Publisher
Taylor&Francis Online
Year of Publication
2022
Format
Journal Article
Topic
Serviceability
Keywords
Indoor Air Quality
Perceived Air Quality
VOC
Emissions
Low-energy Buildings
Research Status
Complete
Series
Wood Material Science & Engineering
Summary
Stricter energy efficiency requirements of buildings have raised concerns about their effects on indoor air quality (IAQ). We studied measured and perceived IAQ in three low-energy wooden test buildings using three ventilation levels (0.5, 1.0, and 2.0 (dm3/s)/m2). IAQ measurements included VOC (volatile organic compounds) air sampling and continuous measurements of several IAQ indicators. Perceived air quality (PAQ) was investigated with a sensory panel of untrained volunteers. The results show that the TVOC (Total VOC) concentrations were relatively low in two of the buildings already at the beginning of the study (100–141 µg/m3), and the concentrations decreased in all test buildings when ventilation was increased from the lowest level. The third building made of pinewood timber showed higher VOC concentrations (340–857 µg/m3), especially for terpene compounds that are generally present in pinewood emissions. In the PAQ assessment, the percentage of people dissatisfied (PD) with the air quality decreased with increased ventilation in all studied buildings. However, at the lowest and highest ventilation, the pinewood building had the second-lowest PD despite higher VOC levels. The findings of this study can be utilized in interpreting the effects of ventilation design and material selection on IAQ in low-energy buildings.
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The Effect of the Environment on the Serviceability of the Cross-Laminated Timber (CLT) Floor: Virtual Reality as a Research Tool

https://research.thinkwood.com/en/permalink/catalogue3364
Year of Publication
2022
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Huang, Haoyu
Zhang, Junhui
Uttley, Jim
Chang, Wen-Shao
Wang, Brad Jianhe
Organization
Newcastle University
Beijing University of Technology
University of Sheffield
Ningbo Sino-Canada Low-Carbon Technology Research Institute
Editor
Branco, Jorge
Publisher
Hindawi
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Serviceability
Keywords
Virtual Reality
Floor Vibration
Human-Induced Vibration
Research Status
Complete
Series
Advances in Civil Engineering
Summary
The environment is one of the factors that may influence occupants’ perception of floor vibration and the assessment of floor serviceability. In this study, laboratory tests were conducted on a 3-ply CLT floor. Occupants’ assessment of the floor serviceability under human-induced vibration was investigated. Virtual reality (VR) technique was used as a research method, simulating two common environments in life. First, the correlation between the occupants’ annoyance rating and serviceability indicators (response factor and vibration dose value (VDV)) was compared with existing standards. The results show that the response factor method in ISO 10137:2007 is conservative for timber floors in both bedroom and gym environments. The VDV method in BS 6472-1:2008 can generally reflect the vibration acceptability of timber floor vibration. Then, the effect of acceleration and environment on the floor serviceability assessment was investigated through statistical methods, respectively. A weak positive correlation between the annoyance rating and the acceleration was found. The effect of the environment on floor vibration assessment was found to be significant.
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Experimental Investigation on the Long-Term Behaviour of Prefabricated Timber-Concrete Composite Beams with Steel Plate Connections

https://research.thinkwood.com/en/permalink/catalogue2741
Year of Publication
2021
Topic
Connections
Serviceability
Material
Timber-Concrete Composite
Application
Beams
Author
Shi, Benkai
Liu, Weiqing
Yang, Huifeng
Publisher
ScienceDirect
Year of Publication
2021
Format
Journal Article
Material
Timber-Concrete Composite
Application
Beams
Topic
Connections
Serviceability
Keywords
TCC
Prefabrication
Steel Plate
Long-term Behaviour
Interface Slip
Loading
Shear Connections
Deflection
Temperature
Humidity
Research Status
Complete
Series
Construction and Building Materials
Summary
This paper presents the results of long-term experiments performed on three timber-concrete composite (TCC) beams. An innovative fabricated steel plate connection system, which consists of screws and steel plates embedded in concrete slabs, was adopted in the TCC beam specimens. The adopted shear connection can provide dry-type connection for TCC beams. Steel plates were embedded in concrete slabs while the concrete slab was constructed in factories. The timber beam and concrete slab can be assembled together using screws at the construction site. In this experimental programme, the beam specimens were subjected to constant loading for 613 days in indoor uncontrolled environments. The influence of long-term loading levels and the number of shear connections on the long-term performance of TCC beams was investigated and discussed. The mid-span deflection, timber strain, and interface relative slip at the positions of both connections and beam-ends were recorded throughout the long-term tests. It was found the long-term deflection of the TCC beam increased by approximately 60% while the long-term loads were doubled. Under the influence of the variable temperature and humidity, the TCC specimens with 8 shear connections showed slighter fluctuations compared with the TCC beam with 6 shear connections. In the 613-day observation period, the maximum deflection increment recorded was 6.56 mm for the specimen with eight shear connections and 20% loading level. A rheological model consisting of two Kelvin bodies was employed to fit the curves of creep coefficients. The final deflections predicted of all specimens at the end of 50-year service life were 2.1~2.7 times the initial deflections caused by the applied loads. All beam specimens showed relative small increments in mid-span deflection, strain and relative slip over time without any degradations, demonstrating the excellent long-term performance of TCC beams using the innovative steel plate connection system, which is also easily fabricated.
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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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139 records – page 1 of 14.