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Concealed Spaces in Mass Timber and Heavy Timber Structures

https://research.thinkwood.com/en/permalink/catalogue2920
Year of Publication
2021
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
NLT (Nail-Laminated Timber)
Application
Floors
Decking
Walls
Roofs
Author
McLain, Richard
Organization
WoodWorks
Year of Publication
2021
Country of Publication
United States
Format
Report
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
NLT (Nail-Laminated Timber)
Application
Floors
Decking
Walls
Roofs
Topic
Fire
Keywords
IBC
Concealed Spaces
Dropped Ceiling
Sprinklers
Noncombustible Insulation
Language
English
Research Status
Complete
Summary
Concealed spaces, such as those created by a dropped ceiling in a floor/ceiling assembly or by a stud wall assembly, have unique requirements in the International Building Code (IBC) to address the potential of fire spread in nonvisible areas of a building. Section 718 of the 2018 IBC includes prescriptive requirements for protection and/or compartmentalization of concealed spaces through the use of draft stopping, fire blocking, sprinklers and other means.
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Cyclic Response of Insulated Steel Angle Brackets Used for Cross-Laminated Timber Connections

https://research.thinkwood.com/en/permalink/catalogue2765
Year of Publication
2021
Topic
Seismic
Acoustics and Vibration
Connections
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Author
Kržan, Meta
Azinovic, Boris
Publisher
Springer
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Topic
Seismic
Acoustics and Vibration
Connections
Keywords
Angle Bracket
Sound Insulation
Insulation
Monotonic Test
Cyclic Tests
Wall-to-Floor
Stiffness
Load Bearing Capacity
Shear
Tensile
Language
English
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
In cross-laminated timber (CLT) buildings, in order to reduce the disturbing transmission of sound over the flanking parts, special insulation layers are used between the CLT walls and slabs, together with insulated angle-bracket connections. However, the influence of such CLT connections and insulation layers on the seismic resistance of CLT structures has not yet been studied. In this paper, experimental investigation on CLT panels installed on insulation bedding and fastened to the CLT floor using an innovative, insulated, steel angle bracket, are presented. The novelty of the investigated angle-bracket connection is, in addition to the sound insulation, its resistance to both shear as well as uplift forces as it is intended to be used instead of traditional angle brackets and hold-down connections to simplify the construction. Therefore, monotonic and cyclic tests on the CLT wall-to-floor connections were performed in shear and tensile/compressive load direction. Specimens with and without insulation under the angle bracket and between the CLT panels were studied and compared. Tests of insulated specimens have proved that the insulation has a marginal influence on the load-bearing capacity; however, it significantly influences the stiffness characteristics. In general, the experiments have shown that the connection could also be used for seismic resistant CLT structures, although some minor improvements should be made.
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Deconstructable Hybrid Connections for the Next Generation of Prefabricated Mass Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue2809
Year of Publication
2021
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Hybrid Building Systems
Shear Walls
Author
Shulman, Samuel
Loss, Cristiano
Organization
University of British Columbia
Year of Publication
2021
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Floors
Hybrid Building Systems
Shear Walls
Topic
Connections
Keywords
Steel Rods
Epoxy
Push-Out-Shear Tests
Prefabrication
Disassembly
Reuse
Language
English
Research Status
Complete
Summary
Timber has been used for building construction for centuries, until the industrial revolution, when it was often replaced by steel and concrete or confined to low-rise housings. In the last thirty years however, thanks to the development of mass timber products and new global interest in sustainability, timber has begun to make a resurgence in the building industry. As building codes and public perception continues to change, the demand for taller and higher-performance timber buildings will only grow. Thus, a need exists for new construction technology appropriate for taller mass timber construction, as well as for fabrication and deconstruction practices that respect wood’s inherent sustainable nature. With this in mind, this research program aims to develop a new hybrid shear connection for mass timber buildings that allows for easy construction, deconstruction, and reuse of the structural elements. This report includes results of Phase 1, which focused on connections consisting of partially threaded 20M and 24M steel rods bonded into pockets formed in CLT and surrounded by thick crowns of high-strength three-component epoxy-based grout. A total of 168 specimens were designed and fabricated, and push-out shear tests carried out with a displacement-controlled monotonic loading protocol. Strength and stiffness values were assessed and effective failure modes in specimens identified. These latter, along with the recorded load-deformation curves, indicate that it is possible to develop mechanics-based design models and design formulas akin to those already used for typical dowel-type fastener timber connections. Additionally, the specimens were easily fabricated in the lab and quickly fastened to the test jig by means of nuts and washers, suggested such connections have a strong potential for prefabrication, disassembly, and reuse.
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Demonstrating Fire-Resistance Ratings for Mass Timber Elements in Tall Wood Structures

https://research.thinkwood.com/en/permalink/catalogue2919
Year of Publication
2021
Topic
Fire
Material
Solid-sawn Heavy Timber
Glulam (Glue-Laminated Timber)
CLT (Cross-Laminated Timber)
Application
Beams
Floors
Author
McLain, Richard
Organization
WoodWorks
Year of Publication
2021
Country of Publication
United States
Format
Report
Material
Solid-sawn Heavy Timber
Glulam (Glue-Laminated Timber)
CLT (Cross-Laminated Timber)
Application
Beams
Floors
Topic
Fire
Keywords
IBC
Minimum Dimensions
Fire Resistance Rating
Noncombustible Protection
Language
English
Research Status
Complete
Summary
Changes to the 2021 International Building Code (IBC) have created opportunities for wood buildings that are much larger and taller than prescriptively allowed in past versions of the code. Occupant safety, and the need to ensure fire performance in particular, was a fundamental consideration as the changes were developed and approved. The result is three new construction types—Type IV-A, IV-B and IV-C—which are based on the previous Heavy Timber construction type (renamed Type IV-HT), but with additional fire protection requirements. One of the main ways to demonstrate that a building will meet the required level of passive fire protection, regardless of structural materials, is through hourly fire-resistance ratings (FRRs) of its elements and assemblies. The IBC defines an FRR as the period of time a building element, component or assembly maintains the ability to confine a fire, continues to perform a given structural function, or both, as determined by the tests, or the methods based on tests, prescribed in Section 703. FRRs for the new construction types are similar to those required for Type I construction, which is primarily steel and concrete. They are found in IBC Table 601, which includes FRR requirements for all construction types and building elements; however, other code sections should be checked for overriding provisions (e.g., occupancy separation, shaft enclosures, etc.) that may alter the requirement.
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Developing a Large Span Timber-based Composite Floor System for Highrise Office Buildings Phase I

https://research.thinkwood.com/en/permalink/catalogue2803
Year of Publication
2021
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
LSL (Laminated Strand Lumber)
Glulam (Glue-Laminated Timber)
Application
Floors
Author
Zhang, Chao
Lee, George
Lam, Frank
Organization
University of British Columbia
Year of Publication
2021
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
LSL (Laminated Strand Lumber)
Glulam (Glue-Laminated Timber)
Application
Floors
Topic
Design and Systems
Keywords
Box Girder
Timber Composite Floor
Span
High-Rise
Tall Wood Buildings
Stiffness
Composite Action
Language
English
Research Status
Complete
Summary
This project proposes a timber-based composite floor that can span 12 m and be used in the construction of 40+ story office buildings. This floor system integrates timber panels and timber beams to form a continuous box girder structure. The timber panels function as the flanges and the timber beams as the web. The beams are spaced and connected to the flange panels so that sufficient bending stiffness of a 12 m span can be achieved via the development of composite action. The current phase of this project studied the performance of the connections between timber elements in the proposed composite member. Six types of connections using different flange material and connection techniques were tested: Cross Laminated Timber (CLT), Laminated Strand Lumber (LSL), Laminated Veneer Lumber (LVL), and Post Laminated Veneer Lumber (PLVL). Glulam was used as the web. The majority of the connections used self-tapping wood screws except one had notches. The load-carrying capacity, stiffness, and ductility of the connections were measured. The stiffness of CLT, LSL, and PLVL connections was in the same range, 19-20 kN/mm per screw. Amongst the three, LSL had the highest peak load and PLVL had the highest proportional limit. The stiffness of the two LVL screw connections was around 13 kN/mm. The notched LVL connection had significantly higher stiffness than the rest, and its peak load was in the same range as LSL, but the failure was brittle. LVL was used to manufacture the full scale timber composite floor element. With a spacing of 400 mm, the overall stiffness reached 33689 N
mm2×109, which was 2.5 times the combined stiffness of two Glulam beams. The predicted overall stiffness based on Gamma method was within 5% of the tested value, and the estimated degree of composite action was 68%. From both the test results and analytical modeling, the number of screws may be further reduced to 50% or less of the current amount, while maintaining a high level of stiffness. Future work includes testing the composite floor under different screw spacings, investigating the effect of concrete topping, and the connections between floor members and other structural elements.
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Diaphragm shear and diagonal compression testing of cross-laminated timber

https://research.thinkwood.com/en/permalink/catalogue2858
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Sharifi, Jonas
Sharifi, Zahra
Berg, Sven
Ekevad, Mats
Organization
Luleå University of Technology
Publisher
Springer
Year of Publication
2021
Country of Publication
Sweden
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Mechanical Properties
Keywords
Diagonal Compression Test
Diaphragm Shear Test
Shear Modulus
Language
English
Research Status
Complete
Series
SN Applied Sciences
Summary
To learn the characteristics of a cross-laminated timber (CLT) panel, it is crucial to perform experimental tests. This study presents two experimental test methods to measure the in-plane shear modulus of CLT panels. This characteristic can be measured by multiple methods such as the picture frame test, the diagonal compression test, and the diaphragm shear test. In this study, the same CLT panels are tested and evaluated in the diaphragm shear test and the diagonal compression test to see if more reliable results can be achieved from the diaphragm shear test. This evaluation is done by experimental tests and finite element simulations. The theoretical pure shear simulation is used as a reference case. Finite element simulations are made for both edge glued and non-edge glued CLT panels. Nine CLT panels are tested in the diaphragm shear test and the diagonal compression test. During ideal conditions (uniform material properties and contact conditions), all three simulated methods result in an almost equal shear modulus. During the experimental testing, the diagonal compression test gives more coherent results with the expected shear modulus based on finite element simulations. Based on the diaphragm shear test results, the CLT panels behave like edge glued, but this situation is dismissed. However, during ideal conditions, the diaphragm shear test is seen as a more reliable method due to the higher proportion of shear in the measured area.
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Effect of cast-in-place concrete application on moisture distribution in timber-concrete composite floors with notched connections, investigated via finite element simulations

https://research.thinkwood.com/en/permalink/catalogue2902
Year of Publication
2021
Topic
Moisture
Material
Timber-Concrete Composite
Application
Floors
Author
Lukacevic, Markus
Autengruber, Maximilian
Raimer, Thomas
Eberhardsteiner, Josef
Füssl, Josef
Organization
TU Wien
Publisher
Elsevier
Year of Publication
2021
Country of Publication
Austria
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Moisture
Keywords
Notches
Moisture Uptake
Sealing
Language
English
Research Status
Complete
Series
Journal of Building Engineering
Summary
Timber-concrete composite (TCC) structures are an efficient way to combine the advantages of cross-laminated timber (CLT) and concrete plates. By cutting notches into the timber part and applying the concrete on top, efficient shear connections can be formed, eliminating the need for additional use of any type of fasteners. However, fresh concrete releases moisture after application, which is absorbed by the highly hygroscopic wood and can lead to a critical reduction in mechanical properties or to problematic situations due to a difference in expansion behavior. Therefore, a separating foil is usually applied between the two materials, which represents an additional time and cost effort and can also negatively influence the connection properties or make the use of notch-only connections impossible. Thus, we investigate numerically what effects the exclusion of such a foil has on the moisture distribution in the CLT plate. Further, the moisture propagation after a fictitious installation on site is analyzed by applying realistic indoor climates to the open wood surface on the bottom of the CLT plate for a period of two years. In addition, the numerical model allows us to study the effect of local sealings of the most critical wooden part, the end-grain surfaces in the notch region. We were able to confirm that, especially in the unsealed case, locally high moisture contents can occur in the critical region next to the notch, where the highest shear stresses are also to be expected. However, by fully sealing the end-grain surfaces in these regions, the moisture levels and thus the risk of failure could be reduced efficiently. The use of such detailed moisture simulations, where moisture uptake due to bleeding of fresh concrete has been calibrated based on experiments, allows the long-term moisture behavior of such critical situations to be studied and effective solutions to be developed.
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Experimental Investigation on Axial Compression of Resilient Nail-Cross-Laminated Timber Panels

https://research.thinkwood.com/en/permalink/catalogue2832
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Nehdi, Moncef
Zhang, Yannian
Gao, Xiaohan
Zhang, V. Lei
Suleiman, R. Ahmed
Organization
Western University
Shenyang Jianzhu University
Editor
Billah, Muntasir
Publisher
MDPI
Year of Publication
2021
Country of Publication
Canada
China
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Mechanical Properties
Keywords
Nails
Axial Compression
Nail-Cross-Laminated Timber
Slenderness Ratio
Language
English
Research Status
Complete
Summary
Conventional cross-laminated timber is an engineered wood product consisting of solid sawn lumber panels glued together. In this study, the structural behavior of solid wood panels of Nail-Cross-Laminated Timber (NCLT) panels connected with nails instead of glue was studied. The failure mode and nail deformation of the novel NCLT panels under axial compression load using eight full-scale NCLT panels was investigated. The effects of four key design parameters, namely, the nail type, number of nails, nail orientation angle, and nail slenderness ratio on axial compression performance of NCLT panels were also analyzed. In addition, a formula for predicting the axial compression bearing capacity of NCLT panels was developed. For calculation of the slenderness ratio, the moment of inertia of the full section or the effective section was determined based on the nail type, number of nails, angle of nail orientation and number of layers of the plate. Results showed that specimens connected by tapping screws had best compressive performance.
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Finite element analysis of alternative load paths to prevent disproportionate collapse in platform-type CLT floor systems

https://research.thinkwood.com/en/permalink/catalogue2901
Year of Publication
2021
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Huber, Johannes
Bita, Hercend
Tannert, Thomas
Berg, Sven
Organization
Luleå University of Technology
University of Northern British Columbia
Publisher
Elsevier
Year of Publication
2021
Country of Publication
Sweden
Canada
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Design and Systems
Keywords
Mass Timber
Structural Robustness
High Fidelity Model
Progressive Collapse
Structural Integrity
Component Model
Language
English
Research Status
Complete
Series
Engineering Structures
Summary
Multi-storey buildings require mitigation of consequences of unexpected or accidental events, to prevent disproportionate collapse after an initial damage. Cross-laminated timber (CLT) in platform-type construction is increasingly used for multi-storey buildings, however, the collapse behaviour and alternative load paths (ALPs) are not fully understood. A 3D non-linear component-based finite element model was developed for a platform-type CLT floor system to study the ALPs after an internal wall loss, in a pushdown analysis. The model, which accounted for connection failure, timber crushing and large displacements, was calibrated to experimental results and then adapted for boundary conditions corresponding to typical residential and office buildings. Subsequently, five parameters (floor span, connection type, vertical location of the floor, tying level, horizontal wall stiffness) were varied, to study their effects on the ALPs in 80 models. The results showed that three ALPs occurred, of which catenary action was the most dominant. Collapse resistance was mainly affected by the floor span, followed by the axial strength, stiffness and ductility of the floor-to-floor connection, the weight of the level above and the floor panel thickness. This study provides an approach to model ALPs in a platform-type CLT floor system to design disproportionate collapse resistant multi-storey CLT buildings.
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From Canada to the World: FPInnovations' Three-Generation Floor Vibration Research and Code Implementation

https://research.thinkwood.com/en/permalink/catalogue2826
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Floors
Author
Hu, Lin
Cuerrier-Auclair, Samuel
Qian, Cheng
Dale, Angela
Organization
FPInnovations
Year of Publication
2021
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Lumber Joists
Engineered Wood Joists
Mass Timber
Floor Vibration-controlled Design Method
CSA 086
National Building Code of Canada
Language
English
Research Status
Complete
Series
InfoNote
Summary
FPInnovations’involvement in various codes and standards technical committees aims to monitor, contributeor propose changes for improvement as well as to create new standards to include new wood products and systems based on knowledge developed from FPInnovations’ research activities. Involvement also allows FPInnovations to be aware of any potential changes to codes and standards and to recognize and address threats and opportunities for wood use. Codes and standards exist to protect consumers but are written to reflect the current practices and knowledge based on a consensus agreement by committee members. FPInnovations’ involvement in codes and standards committees helps to align the coming changes with new wood products. This InfoNote reports on FPInnovations’ contribution to the floor vibration-control design methods on codes and standards implementation and research.
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The Influence of Floor Layering on Airborne Sound Insulation and Impact Noise Reduction: A Study on Cross Laminated Timber (CLT) Structures

https://research.thinkwood.com/en/permalink/catalogue2894
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Bettarello, Federica
Gasparella, Andrea
Caniato, Marco
Organization
University of Trieste
Free University of Bozen
Editor
Piana, Edoardo
Bonfiglio, Paolo
Rychtarikova, Monika
Publisher
MDPI
Year of Publication
2021
Country of Publication
Italy
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Impact Noise Transmission
Sound Insulation
Rubber Ball
Tapping Machine
Sustainable
Language
English
Research Status
Complete
Series
Applied Sciences
Summary
The use of timber constructions recently increased. In particular, Cross Laminated Timber floors are often used in multi-story buildings. The development of standardization processes, product testing, design of details and joints, the speed of construction, and the advantages of eco-sustainability are the main reasons why these structures play a paramount role on the international building scene. However, for further developments, it is essential to investigate sound insulation properties, in order to meet the requirements of indoor comfort and comply with current building regulations. This work presents the results obtained by in field measurements developed using different sound sources (tapping machine, impact rubber ball, and airborne dodecahedral speaker) on Cross Laminated Timber floors, changing different sound insulation layering (suspended ceiling and floating floors). Results clearly show that the influence on noise reduction caused by different layering stimulated by diverse noise source is not constant and furthermore that no available analytical model is able to correctly predict Cross Laminated Timber floors acoustic performances.
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In-situ performance testing of a four storey CLT building in Vancouver. Building vibration and sound insulation

https://research.thinkwood.com/en/permalink/catalogue2909
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Sadegh-Mazloomi, Mohammad
Organization
FPInnovations
Year of Publication
2021
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Ambient Vibration Testing
Acoustic Testing
Insulation
Language
English
Research Status
Complete
Summary
FPInnovations has been conducting a series of field testing on wood mid-rise and tall wood buildings, including this 4-story mass timber building in Vancouver, to measure their dynamic performance. The general objectives of the field measurements of the building wind-induced vibrations and sound insulation performance are to develop improved knowledge and assemble a database of wind-induced vibration and sound insulation performance of mid-rise and tall-wood buildings. Ambient vibration and ASTM acoustic testing were performed to measure the dynamic performance of the building including the building natural frequencies, damping ratios and mode shapes. It was found that the measured first natural frequency and damping ratio of this building are overall similar to those measured from other 4-storey buildings that have exhibited good wind-induced vibration performance. The measured apparent impact insulation performance (AIIC) of 58 is considered as a satisfactory sound insulation performance indicator according to FPInnovations’ field experience about occupant satisfaction. It is believed that the test results will help the designers to obtain insight into the construction details of the building and the correlations between the details and the final performances in terms of building dynamic and sound insulation performance. Furthermore, the test results provided reliable data on the vibration and the sound insulation performance of the selected floor assemblies. The measured AIIC, building natural frequencies, and damping ratios can provide technical reference to architects and engineers to verify their designs and the design tools used.
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Micro-notches as a novel connection system for timber-concrete composite slabs

https://research.thinkwood.com/en/permalink/catalogue2841
Year of Publication
2021
Topic
Connections
Mechanical Properties
Design and Systems
Material
DLT (Dowel Laminated Timber)
Timber-Concrete Composite
Application
Floors
Author
Müller, Katharina
Frangi, Andrea
Organization
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Country of Publication
Switzerland
Format
Journal Article
Material
DLT (Dowel Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Connections
Mechanical Properties
Design and Systems
Keywords
Connection Systems
Experimental Investigations
Sustainable Construction
Micro-notches
Language
English
Research Status
Complete
Series
Engineering Structures
Summary
Timber-concrete composite slabs are more and more in use: the combination of timber and concrete combines the advantages of both materials and offer a valid solution for the increasing demand for sustainable construction. The connection between timber and concrete is the crucial element, yet its potential regarding material and time expenses is not exploited. This paper presents the novel connection system micro-notches, an interlocking concept between timber and concrete with indentations in the millimetre range. Micro-notches provide a continuous shear transfer without additional steel fasteners such as screws or dowels. The paper presents the development of the micro-notch concept in an extensive experimental program supplemented with analytical and numerical models, a calculation model, and practice-relevant guidelines. The results of the investigations show that micro-notches feature an approximately rigid composite action between timber and concrete and a sufficient shear strength for the use in office and residential buildings.
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Multi-criteria decision analysis of timber–concrete composite floor systems in multi-storey wooden buildings

https://research.thinkwood.com/en/permalink/catalogue2865
Year of Publication
2021
Topic
Design and Systems
Material
Timber-Concrete Composite
Application
Floors
Author
Movaffaghi, Hamid
Yitmen, Ibrahim
Organization
Jönköping University
Publisher
Taylor&Francis Group
Year of Publication
2021
Country of Publication
Sweden
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Design and Systems
Keywords
Multi-criteria assessment
Sustainability
Serviceability
Analytical Hierarchy Process
Language
English
Research Status
Complete
Series
Civil Engineering and Environmental Systems
Summary
This study aims to present a multi-criteria decision analysis (MCDA) for comprehensive performance evaluation of the alternative design of timber–concrete composite (TCC) floor system. Considered objectives are serviceability and sustainability performance with associated criterion as (1) comfort class regarding springiness and vibrations, (2) architectural quality with associated criterion as open spaces, (3) environmental aspect with associated criterion as CO2 emissions and (4) cost aspect with associated criterion as the total costs. Analytical Hierarchy Process (AHP) and Complex Proportional Assessment (COPRAS) as the methods in the multi-criteria analysis have been combined for (1) determining the weighting of criteria based on the survey results, (2) verifying the consistency ratio of decision matrix made by experts and (3) for ranking and selecting the optimal concept design among design candidates. According to the results, the TCC floor with the span length of 7.3 m belonging to comfort class A has got the highest ranking. However, sensitivity analysis indicates that the TCC floor with a 9.0 m span length belonging to comfort class A shall be selected as the optimal concept design. The study contributes by developing a complete concept design tool for TCC floor systems using AHP combined COPRAS methods to handle both beneficial and non-beneficial criteria.
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Nonlinear Static Seismic Response of a Building Equipped with Hybrid Cross-Laminated Timber Floor Diaphragms and Concentric X-Braced Steel Frames

https://research.thinkwood.com/en/permalink/catalogue2761
Year of Publication
2021
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Author
Roncari, Andrea
Gobbi, Filippo
Loss, Cristiano
Organization
University of British Columbia
University of Trento
Publisher
MDPI
Year of Publication
2021
Country of Publication
Canada
Italy
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Topic
Seismic
Keywords
Seismic Design
Hybrid Structures
Lateral Resistance
Semi-rigid Diaphragms
Load Distribution
Seismic Performance
Pushover Analysis
Nonlinear Static Analysis
Finite Element Model
Language
English
Research Status
Complete
Series
Buildings
Summary
Simplified seismic design procedures mostly recommend the adoption of rigid floor diaphragms when forming a building’s lateral force-resisting structural system. While rigid behavior is compatible with many reinforced concrete or composite steel-concrete floor systems, the intrinsic stiffness properties of wood and ductile timber connections of timber floor slabs typically make reaching a such comparable in-plane response difficult. Codes or standards in North America widely cover wood-frame construction, with provisions given for both rigid and flexible floor diaphragms designs. Instead, research is ongoing for emerging cross-laminated-timber (CLT) and hybrid CLT-based technologies, with seismic design codification still currently limited. This paper deals with a steel-CLT-based hybrid structure built by assembling braced steel frames with CLT-steel composite floors. Preliminary investigation on the performance of a 3-story building under seismic loads is presented, with particular attention to the influence of in-plane timber diaphragms flexibility on the force distribution and lateral deformation at each story. The building complies with the Italian Building Code damage limit state and ultimate limit state design requirements by considering a moderate seismic hazard scenario. Nonlinear static analyses are performed adopting a finite-element model calibrated based on experimental data. The CLT-steel composite floor in-plane deformability shows mitigated effects on the load distribution into the bracing systems compared to the ideal rigid behavior. On the other hand, the lateral deformation always rises at least 17% and 21% on average, independently of the story and load distribution along the building’s height.
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A Numerical Study of the Stiffness and Strength of Cross-Laminated Timber Wall-to-Floor Connections under Compression Perpendicular to the Grain

https://research.thinkwood.com/en/permalink/catalogue2839
Year of Publication
2021
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Author
Akter, Shaheda
Schweigler, Michael
Serrano, Erik
Bader, Thomas
Organization
Linnaeus University
Lund University
Editor
Brandner, Reinhard
Publisher
MDPI
Year of Publication
2021
Country of Publication
Sweden
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Topic
Connections
Mechanical Properties
Keywords
Parametric Study
Perpendicular to the Grain
Elasto-Plastic Behaviour
Numerical Modeling
Language
English
Research Status
Complete
Series
Buildings
Summary
The use of cross-laminated timber (CLT) in multi-story buildings is increasing due to the potential of wood to reduce green house gas emissions and the high load-bearing capacity of CLT. Compression perpendicular to the grain (CPG) in CLT is an important design aspect, especially in multi-storied platform-type CLT buildings, where CPG stress develops in CLT floors due to loads from the roof or from upper floors. Here, CPG of CLT wall-to-floor connections are studied by means of finite element modeling with elasto-plastic material behavior based on a previously validated Quadratic multi-surface (QMS) failure criterion. Model predictions were first compared with experiments on CLT connections, before the model was used in a parameter study, to investigate the influence of wall and floor thicknesses, the annual ring pattern of the boards and the number of layers in the CLT elements. The finite element model agreed well with experimental findings. Connection stiffness was overestimated, while the strength was only slightly underestimated. The parameter study revealed that the wall thickness effect on the stiffness and strength of the connection was strongest for the practically most relevant wall thicknesses between 80 and about 160 mm. It also showed that an increasing floor thickness leads to higher stiffness and strength, due to the load dispersion effect. The increase was found to be stronger for smaller wall thicknesses. The influence of the annual ring orientation, or the pith location, was assessed as well and showed that boards cut closer to the pith yielded lower stiffness and strength. The findings of the parameter study were fitted with regression equations. Finally, a dimensionless ratio of the wall-to-floor thickness was used for deriving regression equations for stiffness and strength, as well as for load and stiffness increase factors, which could be used for the engineering design of CLT connections.
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Parameter identification for a point-supported cross laminated timber slab based on experimental and numerical modal analysis

https://research.thinkwood.com/en/permalink/catalogue2855
Year of Publication
2021
Topic
Serviceability
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Kawrza, Michael
Furtmüller, Thomas
Adam, Christoph
Maderebner, Roland
Organization
University of Innsbruck
Publisher
Springer
Year of Publication
2021
Country of Publication
Austria
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Serviceability
Acoustics and Vibration
Keywords
Modal Analysis
Complex Mode Shape
Point-Supported
Language
English
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
In this paper, the dynamic properties of a point-supported cross-laminated timber slab are studied in order to determine the elastic material parameters on this basis. A detailed experimental modal analysis of the slab with dimensions 16.0 m x 11.0 m is performed, and seven modes including the natural frequencies, damping ratios and mode shape components at 651 sensor positions are identified. The found mode shapes are complex due to environmental influences that occurred during the two-day measurement campaign. This error is corrected by eliminating these influences. A finite element model of the slab is presented, whose parameters in terms of material properties and boundary conditions are determined by a model updating procedure. Based on the modal properties of the seven experimentally identified modes, an accurate and robust parameter set is obtained, which can be used in further numerical studies of the considered CLT to check serviceability limit criteria.
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Predicting the Human-Induced Vibration of Cross Laminated Timber Floor Under Multi-Person Loadings

https://research.thinkwood.com/en/permalink/catalogue2701
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Wang, Chang
Chang, Wen-Shao
Yan, Weiming
Huang, Haoyu
Publisher
ScienceDirect
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Human-Induced Vibration
Multi-Person Loadings
Numerical Modelling
Language
English
Research Status
Complete
Series
Structures
Summary
The vibration of cross laminated timber (CLT) floor is closely related to human-induced loadings. However, research and prediction approaches regarding human-induced vibration of the CLT floor have been mostly limited to a single-person excitation condition. This paper presents new prediction approaches to the vibration response of the CLT floor under multi-person loadings. The effect of multi-person loadings on the vibration performance of a CLT floor was investigated through numerical modelling, experimental testing and analytical investigation. A finite element model was developed through a computational software to perform an accurate analysis of human-induced loadings. An analytical model was established to predict human-induced vibration of the CLT floor under multi-person loadings. Experimental tests were conducted to validate the numerical modelling. Results of both numerical modelling and experimental testing showed that the vibration performance of the CLT floor under multi-person loadings was almost double that under single-person loadings. Thus, multi-person activities are more likely to cause the occupants feelings of discomfort. A method for predicting the human-induced vibration of the CLT floor under multi-person loadings was then developed. The measured response, numerical modelled response, and predicted response were compared using an existing design metric, vibration dose value (VDV). The results were largely consistent. It is therefore concluded that the proposed prediction method will enable engineers to design timber floor systems that consider multi-person loadings.
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Structural Capacity of One-Way Spanning Large-Scale Cross-Laminated Timber Slabs in Standard and Natural Fires

https://research.thinkwood.com/en/permalink/catalogue2734
Year of Publication
2021
Topic
Fire
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Ceilings
Author
Wiesner, Felix
Bartlett, Alastair
Mohaine, Siyimane
Robert, Fabienne
McNamee, Robert
Mindeguia, Jean-Christophe
Bisby, Luke
Organization
University of Queensland
The University of Edinburgh
CERIB Fire Testing Centre
Brandskyddslaget
University of Bordeaux
Publisher
Springer
Year of Publication
2021
Country of Publication
Australia
United Kingdom
France
Sweden
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Ceilings
Topic
Fire
Mechanical Properties
Keywords
Deflection
Temperature
Load Bearing Capacity
Ventilation
Fire Safety
Language
English
Research Status
Complete
Series
Fire Technology
Summary
This paper describes selected observations, measurements, and analysis from a series of large-scale experiments on cross-laminated timber (CLT) slabs that were exposed to fire from below, using four different heating scenarios, with a sustained mechanical loading of 6.3 kN m per metre width of slab. The deflection response and in-depth timber temperatures are used to compare the experimental response against a relatively simple structural fire model to assess the load bearing capacity of CLT elements in fire, including during the decay phase of natural fires. It is demonstrated that the ventilation conditions in experiments with a fixed fuel load are important in achieving burnout of the contents before structural collapse occurs. A mechanics-based structural fire model is shown to provide reasonably accurate predictions of structural failure (or lack thereof) for the experiments presented herein. The results confirm the importance of the ventilation conditions on the fire dynamics, burning duration, and the achievement of functional fire safety objectives (i.e. maintaining stability and compartmentation), in compartments with exposed CLT.
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U.S. Mass Timber Floor Vibration Design Guide

https://research.thinkwood.com/en/permalink/catalogue2874
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
NLT (Nail-Laminated Timber)
DLT (Dowel Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Organization
WoodWorks
Year of Publication
2021
Country of Publication
United States
Format
Book/Guide
Material
CLT (Cross-Laminated Timber)
NLT (Nail-Laminated Timber)
DLT (Dowel Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Floor Vibration
Vibration Design Methods
Finite Element Modeling
Language
English
Research Status
Complete
Summary
The scope of this guide focuses on the design of mass timber floor systems to limit human-induced vibration. The primary performance goal is to help designers achieve a low probability of adverse comment regarding floor vibrations in a manner consistent with the vibration design guides for steel and concrete systems. This includes excitation primarily from human walking as observed by other people in the building. Some treatment of design for sensitive equipment in response to human walking is also discussed. This design guide covers the range of currently available mass timber panels, including cross-laminated timber (CLT) manufactured from either solid sawn or structural composite lumber (SCL) laminations, nail-laminated timber (NLT), dowel laminated timber (DLT) and glue-laminated timber (GLT), as well as their support framework of timber beams. The target user of this guide is a design professional with working knowledge of mass timber structural design and some background knowledge of structural dynamics as related to floor vibrations. It may be particularly useful to design engineers with limited experience with vibration analysis, experienced multi-material engineers familiar with vibration analysis but unfamiliar with mass timber vibration, and applications engineers assisting manufacturers in the development of solutions and proposals for projects.
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