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2395 records – page 2 of 240.

Experimental investigation of hygrothermal behavior of wooden-frame house under real climate conditions

https://research.thinkwood.com/en/permalink/catalogue3338
Year of Publication
2023
Topic
Moisture
Author
Rahim, Mourad
Djedjig, Rabah
Wu, Dongxia
Bennacer, Rachid
Ganaoui, Mohammed EL
Organization
University of Lorraine
University of Paris-Saclay
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Topic
Moisture
Keywords
Hygrothermal Behavior
Heat and Mass Transfer
Bio-based Building Envelope
Research Status
Complete
Series
Energy and Built Environment
Summary
This paper deals with the experimental investigation of hygrothermal behavior of wooden-frame building envelope. The experiment was based on in-situ monitoring of a full size experimental monozone house built at the University of Lorraine. Variations in temperature and relative humidity inside and outside the envelope were logged simultaneously with local meteorological data. Results showed the high coupling between temperature and relative humidity variations within the envelope materials. An overall hygrothermal response of the wall highlighted an interesting hygrothermal dynamic behavior of the envelope which may contribute to mitigate variations of relative humidity inside the building. Nevertheless, relative humidity evolves within a range of values that can lead to mold growth at a certain position which may alter wooden envelope life.
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Innovative solutions to improved sound insulation of CLT floors

https://research.thinkwood.com/en/permalink/catalogue3339
Year of Publication
2023
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Ljunggren, Fredrik
Organization
Luleå University of Technology
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Sound Insulation
Low Frequencies
Impact Sound
Compressed Wood
Research Status
Complete
Series
Developments in the Built Environment
Summary
Building with cross laminated timber (CLT) has gain increased interest over the last years, but in common to other wood-based building systems, inadequate low-frequency sound insulation is seen as a problem. This paper deals with two methods to improve the sound insulation of CLT panels, normally made from spruce: 1) heavy CLT, introducing compressed, i.e. densified, spruce as well as alternative wood species, and 2) elastic layer based upon shear motion. In addition to a series of laboratory measurements, a full-scale CLT floor made of two 60 mm birch panels with a 12 mm elastic layer in between was tested in a two-room test mock-up. The results from the acoustical measurements showed that the floor has about 7 dB greater airborne and impact sound insulation for one-third octave bands, 50–3150 Hz, compared to a standard CLT floor of the same total height.
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Influence of inter-panel connections on vibration response of CLT floors due to pedestrian-induced loading

https://research.thinkwood.com/en/permalink/catalogue3340
Year of Publication
2023
Topic
Connections
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Milojevic, Marija
Racic, Vitomir
Marjanovic, Miroslav
Nefovska-Danilovic, Marija
Organization
University of Belgrade
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Connections
Acoustics and Vibration
Keywords
Walking Forces
Human-induced Vibrations
Single Surface Spline
Half-lapped Joint
Research Status
Complete
Series
Engineering Structures
Summary
Long-span cross-laminated timber (CLT) floors are typically an assembly of prefabricated CLT panels connected together on the site. The actual connections are commonly neglected in design calculations. Hence, a CLT floor is modelled either as a monolith slab or more frequently as a set of CLT panels with no connections at all. This paper presents a numerical study designed to examine the influence of two most common inter-panel connections, i.e. single surface spline and half-lapped joint, on vibration modes and vibration responses of a range of different CLT floors due to pedestrian-induced loading. Although the inter-panel connections are relatively complex in reality, they are modelled here as an equivalent 2D elastic strip between the CLT panels. This relatively simple yet robust model can be used with ease in design practice, regardless finite element (FE) software used to extract vibration modes of a CLT floor. The corresponding monolith floors and floors without inter-panel connections are studied for the comparison of the results. Vertical vibration responses are simulated for low-frequency and high-frequency floors using the corresponding walking force models given in a popular design guideline for footfall induced vibrations of civil engineering structures. Vibration responses were calculated for single pedestrian occupants and their walking paths parallel and perpendicular to the line of connection. The results showed that including the inter-panel connections in a FE model resulted in up to 2.5 higher RMS acceleration levels. Hence, the common practice of modelling CLT floors as monolith slabs or as a set of panels without connections should be left behind.
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Mechanical properties of fast-growing poplar glulam columns reinforced with steel plate

https://research.thinkwood.com/en/permalink/catalogue3341
Year of Publication
2023
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Author
Wang, Yuzhou
Liang, Chen
Zhang, Bingjie
Qu, Shuang
Gao, Ying
Zhang, Xiao
Organization
Shandong Xiehe University
Key Laboratory of Building Structural Retrofitting and Underground Space Engineering
Shandong Jianzhu University
Southeast University
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Topic
Mechanical Properties
Keywords
Fast-growing Poplar
Steel Reinforced Glulam
Compression Test
Research Status
Complete
Series
Case Studies in Construction Materials
Summary
Fast-growing poplar with characteristics of fast growth, convenient processing, and strong adaptability is widely planted all over the world, but it is difficult to be directly used as structural timber due to its loose fibers and low strength. In order to enhance mechanical properties of fast-growing poplar, a new type of steel plate reinforced glulam fast-growing poplar is developed. Nine columns are tested including one fast-growing poplar column, two glued-laminated timber (glulam) columns and six steel plate reinforced glulam columns. The influencing factors include the steel plate thickness and eccentricity. Based on test results, axial stiffness, failure mode, load-displacement and load-strain relationships were investigated. Test results indicate that ultimate load and axial stiffness of steel plate reinforced glulam columns were respectively increased by 134.5–177.5% and 168.5–244.1% compared to fast-growing poplar column. With the increase of steel plate thickness and decrease of eccentricity, ultimate load increased by 10.9–18.3% and 27.2–92.3%, respectively. It was found that steel plate thickness and eccentricity have great impacts on bearing capacity of steel plate reinforced glulam columns. In addition, bearing capacity equation for steel plate reinforced glulam columns was established and test results coincide quite well with calculated results with difference of less than 5%.
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Effects of building height on the sound transmission in cross-laminated timber Buildings – Airborne sound insulation

https://research.thinkwood.com/en/permalink/catalogue3342
Year of Publication
2023
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Nilsson, Erik
Ménard, Sylvain
Bard, Delphine
Hagberg, Klas
Organization
University of Québec at Chicoutimi
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Acoustics and Vibration
Keywords
Building Height
Viscoelastic Interlayer
Airborne Sound Insulation
Research Status
Complete
Series
Building and Environment
Summary
Buildings constructed with cross-laminated timber (CLT) are increasing in interest in several countries. Since CLT is a sustainable product, it can help the building industry to reduce greenhouse gas emissions. Furthermore, buildings constructed with CLT are increasing in building height, thereby increasing the load on the junctions and structural building elements further down in the building. Several studies have investigated how the load impacts the sound transmission between apartments. The majority found that an increasing load could have a negative effect on the vertical sound insulation. However, the findings are limited to a few measurements or building elements, and the studies only investigate junctions with resilient interlayers. This article aims to investigate if the building height, and thereby the load, affect the vertical airborne sound insulation between apartments on different stories in different cross-laminated timber buildings, with or without the presence of viscoelastic interlayers, and to quantify the effect. Four CLT buildings with different building systems, building heights, and the presence of viscoelastic interlayers in the junctions were measured. The airborne sound insulation between different apartment rooms was measured vertically for stories on the lower and higher levels. The difference in airborne sound insulation was calculated separately for each building, and the measurements indicate that the vertical airborne sound insulation reduces further down in the buildings. Therefore, results show that increasing load, by an increasing number of stories, has a negative effect on the vertical airborne sound insulation.
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Behavior of cross-laminated timber panels during and after an ISO-fire: An experimental analysis

https://research.thinkwood.com/en/permalink/catalogue3343
Year of Publication
2023
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Author
Vairo, Maurizio
Silva, Valdir Pignatta
Icimoto, Felipe Hideyoshi
Organization
University of Sao Paulo
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Keywords
Charring
ISO-fire
Post-fire Stiffness Reduction
Cooling Phase
Finite Element Analysis
Research Status
Complete
Series
Results in Engineering
Summary
Cross-laminated timber has been used in buildings since the 1990s. In the last years, there has been a growing interest in the use of this technology, especially with the adoption of the product in increasingly taller buildings. Considering that the product is manufactured from a combustible material, wood, authorities that regulate the fire safety in buildings and the scientific community have carried out numerous research and fire tests, aiming to elaborate codes which contemplate the use of cross-laminated timber in tall buildings. This paper discusses the main results obtained from the fire resistance test of a cross-laminated timber slab carried out in the horizontal gas furnace (3.0 m × 4.0 m x 1.5 m) from the University of Sao Paulo. A vertical load of 3 kN/m2 was applied over the slab and the specimens were exposed to the standard fire curve for 30 min. In addition to the 30-min test, the research also evaluated the thermal behavior of the samples during the 24 h after the burners were turned off. Throughout the test, the slab maintained the integrity and the thermal insulation, and no falling-off of the charred layer was observed. However, the 24-h test indicated that it is mandatory to consider the loss of stiffness and strength of timber caused by the thermal wave observed during the decay phase.
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Dynamic testing and numerical modelling of a pedestrian timber bridge at different construction stages

https://research.thinkwood.com/en/permalink/catalogue3344
Year of Publication
2023
Topic
Acoustics and Vibration
Material
Glulam (Glue-Laminated Timber)
Application
Bridges and Spans
Author
Bergenudd, Jens
Battini, Jean-Marc
Crocetti, Roberto
Pacoste, Costin
Organization
KTH royal institute of technology
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Bridges and Spans
Topic
Acoustics and Vibration
Keywords
Pedestrian Bridge
Railings
Asphalt
Dynamic Analysis
Finite Element Modelling
Research Status
Complete
Series
Engineering Structures
Summary
This article studies the dynamic properties of a single span pedestrian timber bridge by in-situ testing and numerical modelling. The in-situ dynamic tests are performed at four different construction stages: (1) on only the timber structure, (2) on the timber structure with the railings, (3) on the timber structure with railings and an asphalt layer during warm conditions and (4) same as stage 3 but during cold conditions. Finite element models for the four construction stages are thereafter implemented and calibrated against the experimental results. The purpose of the study is to better understand how the different parts of the bridge contribute to the overall dynamic properties. The finite element analysis at stage 1 shows that longitudinal springs must be introduced at the supports of the bridge to get accurate results. The experimental results at stage 2 show that the railings contributes to 10% of both the stiffness and mass of the bridge. A shell model of the railings is implemented and calibrated in order to fit with the experimental results. The resonance frequencies decrease with 10–20% at stage 3 compared to stage 2. At stage 3 it is sufficient to introduce the asphalt as an additional mass in the finite element model. For that, a shell layer with surface elements is the best approach. The resonance frequencies increase with 15–30% between warm (stage 3) and cold conditions (stage 4). The stiffness of the asphalt therefore needs to be considered at stage 4. The continuity of the asphalt layer could also increase the overall stiffness of the bridge. The damping ratios increase at all construction stages. They are around 2% at warm conditions and around 2.5% at cold conditions for the finished bridge.
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Comparative CO2 emissions of concrete and timber slabs with equivalent structural performance

https://research.thinkwood.com/en/permalink/catalogue3345
Year of Publication
2023
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Author
Oh, Jae-Won
Park, Keum-Sung
Kim, Hyeon Soo
Kim, Ik
Pang, Sung-Jun
Ahn, Kyung-Sun
Oh, Jung-Kwon
Organization
Seoul National University
Korea Institute of Civil Engineering and Building Technology
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Topic
Environmental Impact
Keywords
Carbon Dioxide
Reinforced Concrete
Structural Performance
Environmental Product Declaration
Research Status
Complete
Series
Energy and Buildings
Summary
Comparing the environmental impacts of building materials at the building level can be biased because a building design is optimized for a primary structural material. To achieve objective comparisons, this study compares the environmental impact of reinforced concrete (RC), cross-laminated timber (CLT), and timber-concrete composite (TCC) at the component level with equivalent structural performance. A slab was selected as the target structure member because its design does not consider lateral forces. Equivalent structural performance was defined as the minimum quantity of slab materials for comparable span and live load conditions. The functional unit for this study was defined as a 1 m2 slab. The system boundary covered the cradle-to-gate perspective, including raw material extraction, transportation, and manufacturing. The structural design method and material design values followed the Korean building code and standards. Environmental product declaration data developed in Korea were used to evaluate the carbon footprint. The CLT emitted 75 % less carbon dioxide, the primary greenhouse gases responsible for anthropogenic climate change, compared with RC regardless of conditions, while the TCC emitted 65 % less CO2, and its environmental impact improved as the span lengthened. The results also indicated that timber slabs are thinner than concrete slabs and can be structurally rational.
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Size effect on bending strength of glued laminated timber predicted by a numerical simulation concept including discrete cracking

https://research.thinkwood.com/en/permalink/catalogue3346
Year of Publication
2023
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Vida, Christoffer
Lukacevic, Markus
Hochreiner, Georg
Füssl, Josef
Organization
TU Wien
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Size Effect
XFEM
Failure Mechanisms
Research Status
Complete
Series
Materials & Design
Summary
The dimensions, particularly the depths, of glued laminated timber (GLT) beams are continuously increasing to realize, e.g., wide-span hall constructions or flexible office buildings. However, experimental investigations of large beams are unavailable because of the tremendous effort involved. Numerical simulation campaigns represent an alternative, but their results are heavily influenced by the modeling strategy, and therefore, a different influence of the beam depths on the bending strength was obtained. To predict this influence, also called size effect, we carried out a simulation program covering 8840 GLT beams ranging from 165 mm to 3300 mm in depth, using advanced modeling concepts including discrete cracking and plasticity. We observed a decreasing characteristic bending strength with increasing beam depths and an almost constant mean modulus of elasticity for both considered strength classes. Additionally, the influence of the beam length on the bending strength is analyzed, and it is shown that this influence can be described reasonably well with a simple analytical model based on Weibull’s strength theory. In conclusion, the effective material behavior of GLT is affected by its dimensions. For large beams, this influence is difficult to obtain experimentally; however, numerical simulation campaigns seem to be a promising way to accomplish this.
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Experimental study on bending properties of bamboo-wood composite beams with different tectonic patterns

https://research.thinkwood.com/en/permalink/catalogue3347
Year of Publication
2023
Topic
Mechanical Properties
Application
Beams
Author
Zhang, Zichen
Qiu, Zhenyu
Organization
Nanjing Forestry University
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Application
Beams
Topic
Mechanical Properties
Keywords
Bamboo-wood Composite
Bending Properties
Tectonic Pattern
Research Status
Complete
Series
Polymer Testing
Summary
This study investigated the mechanical properties of bamboo-wood composite beams by conducting four-point bending static load tests on eight laminated beams. It was shown that a new bamboo-wood composite material was obtained by laminating denser laminated bamboo to the surface of timber panels employing hot pressing. Failure of the beams was mainly due to interlaminar shear damage and brittle fracture at the bottom. The test results showed that the polyurethane and epoxy binders ensured good interlaminar bonding properties. In the same adhesive specimen, the increase in the number of bamboo panels increased the ultimate load-carrying capacity of the bamboo-wood composite beams. The predicted load capacity using the equivalent section calculation method agreed well with the experimental results and was effective for assessing the mechanical properties of bamboo-wood composite laminated beams.
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2395 records – page 2 of 240.