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Experimental and numerical modal analysis of a cross laminated timber floor system in different construction states

https://research.thinkwood.com/en/permalink/catalogue3145
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Kawrza, Michael
Furtmüller, Thomas
Adam, Christoph
Organization
University of Innsbruck
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Floor Construction
Footfall Sound Insulation
Modal Analysis
Optimization
Research Status
Complete
Series
Construction and Building Materials
Summary
This paper addresses the vibration characteristics of a cross laminated timber (CLT) floor in a residential building during three construction states. Experimental modal analyses are carried out on the blank CLT slab, on the slab with added drywall ceiling, and on the slab with drywall ceiling and added floating screed. A reliable numerical model of the system is created with the means of a finite element model updating procedure. This model shows that some experimentally determined modes can be attributed to the dynamic interaction with the shaker used for excitation during the tests. In the finite element model, this effect can subsequently be eliminated. Based on the validated numerical model, the impact of various parameters of the floor construction on the low-frequency footfall sound insulation is investigated.
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Experimental and numerical study on the bending response of a prefabricated composite CLT-steel floor module

https://research.thinkwood.com/en/permalink/catalogue3047
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Author
Owolabi, David
Loss, Cristiano
Organization
University of British Columbia
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Composite Floors
Hybrid Construction
Mass Timber
Cross-laminated Timber
Prefabricated Construction
Low-Carbon Structures
Bending Stiffness
Research Status
Complete
Series
Engineering Structures
Summary
Cross-laminated timber (CLT) is one of the most widely utilized mass timber products for floor construction given its sustainability, widespread availability, ease of fabrication and installation. Composite CLT-based assemblies are emerging alternatives to provide flooring systems with efficient design and optimal structural performance. In this paper, a novel prefabricated CLT-steel composite floor module is investigated. Its structural response to out-of-plane static loads is assessed via 6-point bending tests and 3D finite-element computational analysis. For simply supported conditions, the results of the investigation demonstrate that the floor attains a high level of composite efficiency (98%), and its bending stiffness is about 2.5 times those of its components combined. Within the design load range, the strain diagrams are linear and not affected by the discontinuous arrangement and variable spacing of the shear connectors. The composite floor module can reach large deflection without premature failure in the elements or shear connectors, with plasticity developed in the cold-formed steel beams and a maximum attained load 3.8 times its ultimate limit state design load. The gravity design of the composite module is shown to be governed by its serviceability deflection requirements. However, knowledge gaps still exist on the vibration, fire, and long-term behaviour of this composite CLT-steel floor system.
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Experimental Investigation on Bending Behavior of Innovative Poplar LVL Floor Diaphragms

https://research.thinkwood.com/en/permalink/catalogue3213
Year of Publication
2022
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Application
Floors
Author
Sun, Xufeng
Wang, Changyuan
Liu Yan
Ma Hongwei
Tang, Shukai
Organization
Yangzhou University
Editor
Zhang, Nan
Chen, Lingkun
Zhang, Qinghua
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Application
Floors
Topic
Mechanical Properties
Keywords
Poplar LVL
Floor Diaphragm
Orthogonal Rib Beam
Bending Behavior
Experimental Tests
Research Status
Complete
Series
Sustainability
Summary
Poplar laminated veneer lumber (poplar LVL) is made of fast-growing poplar veneer and structural adhesive, which owns the advantages of sustainability and stable quality. Here an innovative poplar LVL floor diaphragm is presented, mainly made up of orthogonal rib beams fitted together using L-shape steel connectors. The paper mainly deals with an experimental study on the bending behavior of the floor under transverse uniform load. Full-scale testing on eight 3.6 m × 4.8 m specimens shows that the damage phenomena of the floor mainly exhibited as the separation between the rib beams and pulling out from the rib beam for the tapping screw. Though some local damage phenomena appeared before the preset maximum loading level, the load-deflection curves basically kept linear for most of the specimens. Under the service load level of 2.5 kN/m2, the distribution of deflection and strain for the full-length rib beam substantially exhibited the characteristic of a two-way slab. In contrast, for the segmented rib beam, the situation was much more complex. Due to the parametric design of the specimens, testing results illustrated that the rib beam height played the most important role in floor stiffness. Next was the sheathing panel, while the role of segmented rib beam spacing was relatively unremarkable. At last, a revised pseudo-plate method was proposed to evaluate the maximum deflection of the novel floor, which considered the composite action by rigidity factors.
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Influence of the connector shape parameters in the structural behaviour of the adhesive-free timber floor panels

https://research.thinkwood.com/en/permalink/catalogue3125
Year of Publication
2022
Topic
Mechanical Properties
Application
Floors
Author
Moltini, Gonzalo
Baño, Vanesa
Organization
Universidad de la República
Publisher
Elsevier
Year of Publication
2022
Format
Conference Paper
Application
Floors
Topic
Mechanical Properties
Keywords
Adhesive-free Connection
Structural Yield
Timber-to-timber Panels
Conference
ICSI 2021 The 4th International Conference on Structural Integrity
Research Status
Complete
Series
Procedia Structural Integrity
Summary
Timber-to-timber panels (TTPs) are adhesive- and steel-free structural components formed by carpentry joints of Scots pine to be used as floors. A numerical model simulating bending tests on TTPs and considering timber as an orthotropic and bi-modulus material was validated from experimental results of deflection, and rolling shear strength. Since the serviceability and ultimate limit states of the TTPs was mainly defined by the rolling shear properties of the connectors, this paper aims to study the influence of different connector shape parameters in the structural behavior of the panels. For that, values of the connector height (hc varying between 40 and 100 mm), width (b1 varying between 40 and 100 mm) and the dove-tail angle (a varying between 45º and 75º) were introduced in the numerical models to obtain both failure load and stiffness for different span TTPs. Results showed that TTP deflection and shear stresses on the connectors decreases with the increase of the height and the width of the connectors. As the width of the connector (b1) increases, the maximum shear stress decreases up to 42%. For a same connector height, the angle of the dove-tail shows low influence in the maximum shear stress; however, it plays a greater role in the deflection of the panels. For the connectors of 40 mm of height TTP deflection was barely influenced by connector width; however, for higher connectors (hc = 60 mm), TTP deflection decreased up to 41% as width increases. So, new TTPs configurations varying the connector parameters showed an improvement on the deflection and on the shear stresses of the connectors.
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Mechanical Behavior of GFRP Dowel Connections to Cross Laminated Timber-CLT Panels

https://research.thinkwood.com/en/permalink/catalogue2957
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Almeida, Amanda
Moura, Jorge
Organization
Maringá State University
Londrina State University
Editor
Knapic, Sofia
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Connections
Keywords
GFRP
Dowel-Type Connections
Panel-to-Panel
Design Methodology
Push-Out Tests
Research Status
Complete
Series
Forests
Summary
Sustainability issues are driving the civil construction industry to adopt and study more environmentally friendly technologies as an alternative to traditional masonry/concrete construction. In this context, plantation wood especially stands out as a constituent of the cross-laminated timber (CLT) system, laminated wood glued in perpendicular layers forming a solid-wood structural panel. CLT panels are commonly connected by screws or nails, and several authors have investigated the behavior of these connections. Glass-fiber-reinforced polymer (GFRP) dowels have been used to connect wooden structures, and have presented excellent performance results; however, they have not yet been tested in CLT. Therefore, the objective of this study is to analyze the glass-fiber-reinforced polymer (GFRP)-doweled connections between CLT panels. The specimens were submitted to monotonic shear loading, following the test protocol described in EN 26891-1991. Two configurations of adjacent five-layer panels were tested: flat-butt connections with 45° dowels (x, y, and z axes), and half-lap connections with 90° dowels. The results were evaluated according to the mechanical connection properties of strength, stiffness, and ductility ratio. The results showed higher stiffness for butt-end connections. In terms of strength, the half-lap connections were stronger than the butt-end connections.
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Optimal Design and Competitive Spans of Timber Floor Joists Based on Multi-Parametric MINLP Optimization

https://research.thinkwood.com/en/permalink/catalogue3041
Year of Publication
2022
Topic
Cost
Application
Floors
Author
Jelušic, Primož
Kravanja, Stojan
Organization
University of Maribor
Editor
Giannopoulos, Georgios
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Application
Floors
Topic
Cost
Keywords
Structural Optimization
Cost Optimization
Discrete Optimization
Mixed-Integer Nonlinear Programming
MINLP
Timber Floor Joists
Research Status
Complete
Series
Materials
Summary
This study investigates the optimization of the design of timber floor joists, taking into account the self-manufacturing costs and the discrete sizes of the structure. This non-linear and discrete class of optimization problem was solved with the multi-parametric mixed-integer non-linear programming (MINLP). An MINLP optimization model was developed. In the model, an accurate objective function of the material and labor costs of the structure was subjected to design, strength, vibration and deflection (in)equality constraints, defined according to Eurocode regulations. The optimal design of timber floor joists was investigated for different floor systems, different materials (sawn wood and glulam), different load sharing systems, different vertical imposed loads, different spans, and different alternatives of discrete cross-sections. For the above parameters, 380 individual MINLP optimizations were performed. Based on the results obtained, a recommended optimal design for timber floor joists was developed. Engineers can select from the recommendations the optimal design system for a given imposed load and span of the structure. Economically suitable spans for timber floor joists structures were found. The current knowledge of competitive spans for timber floor joists is extended based on cost optimization and Eurocode standards.
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Optimization framework for cost and carbon emission of timber floor elements

https://research.thinkwood.com/en/permalink/catalogue3001
Year of Publication
2022
Topic
Cost
Environmental Impact
Application
Floors
Author
Nesheim, Sveinung
Mela, Kristo
Malo, Kjell
Labonnote, Nathalie
Organization
Norwegian University of Science and Technology
Tampere University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Application
Floors
Topic
Cost
Environmental Impact
Keywords
Cost Optimization
Carbon Emission Reduction
Timber Floor
Eurocode 5
Research Status
Complete
Series
Engineering Structures
Summary
Long-span timber floor elements increase the adaptability of a building and they exhibit a significant market potential. High cost of the floor elements is a challenge, and the timber sector is under substantial pressure to find more economical solutions without weakening otherwise favourable environmental performance. The range of technical timber-based materials and components, structural typologies, overlays and ceiling systems represent an immense solution space when searching for a competitive design for a specific building application. Finding the optimum solution requires a computational procedure. In this study a recent development for the accounting of manufacturing resources for timber elements is utilized to build an optimization framework for cost and ECO2 minimisation of timber floor elements finalized at the factory gate. The design of the element is formulated as a discrete optimization problem which is solved by a mixed-integer sequential linearization procedure. Various material combinations and constraint combinations are treated. The optimization framework provides a tool for rapid design exploration that can be used in timber floor design situations. The results of the calculations carried out in this study provide insight on the general trends of optimum floor elements. The optimization model is used to analyse the characteristics of the optimum designs, and a comparison between the current and the proposed method for the second generation of Eurocode 5 is chosen as a vehicle for demonstrating achievable implications.
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Prediction of bending performance for a separable CLT-concrete composite slab connected by notch connectors

https://research.thinkwood.com/en/permalink/catalogue2931
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Author
Pang, Sung-Jun
Ahn, Kyung-Sun
Jeong, Seok-man
Lee, Gun-Cheol
Kim, Hyeon Soo
Oh, Jung-Kwon
Organization
Seoul National University
Korea National University of Transportation
Korea Institute of Civil Engineering and Building Technology
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Composite Slab
Bending Strength
Notched Connection
Round Notch
Research Status
Complete
Series
Journal of Building Engineering
Summary
In this study, the bending performance of a separable cross-laminated timber (CLT)–concrete composite slab for reducing environmental impact was investigated. The slab has consisted of CLT and eco–concrete, and round-notch shape shear connectors resist the shear force between the CLT and eco-concrete. The eco–concrete was composed of a high-sulfated calcium silicate (HSCS) cement, which ensures low energy consumption in the production process. The bending stiffness and load-carrying capacities of the slab were theoretically predicted based on the shear properties of the notch connectors and validated with an experimental test. The shear properties of two types of notch shear connectors (Ø100 mm and Ø200 mm) were measured by planar shear tests. As a result, the stochastically predicted bending stiffness of the slab (with Ø100 mm shear connector) was 0.364 × 1012 N mm2, which was almost similar to test data. The load-carrying capacities of the slab were governed by the shear failure of the notch connectors, and the lower fifth percentile point estimate (5% PE) was 21.9 kN, which was 7.9% higher than the prediction (20.2 kN). In a parameter study, the effect of notch diameter for the CLT-concrete slab span was analyzed depending on the applied loads, and the maximum spans of the slab with Ø100 mm notch or Ø200 mm notch were not significantly different.
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Shear performances of hybrid notch-screw connections for timber-concrete composite structures

https://research.thinkwood.com/en/permalink/catalogue3383
Year of Publication
2022
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Shi, Benkai
Dai, Yongqing
Tao, Haotian
Yang, Huifeng
Organization
Nanjing Tech University
Southeast University
Year of Publication
2022
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Connections
Mechanical Properties
Keywords
Hybrid Notch-screw Connection
Ductility
Slip Modulus
Push-Out Tests
Research Status
Complete
Series
BioResources
Summary
This paper presents the push-out experimental results of hybrid notch-screw (HNS) connections for timber-concrete composite structures. A total of 7 groups of specimens were designed and tested. The experimental parameters included the loading constraint conditions (i.e., the test specimens were loaded either in local compression or in uniform compression), shapes of notches in the wood, screw number in notch, notch width, and the inclusion of a self-tapping screw reinforcement for timber or not. The experimental results were discussed in terms of failure modes, ultimate strength, slip moduli, and ductility. The yield strengths and ductility factors were determined based on the load-slip curves according to existing standards. The experimental results showed that both the shear timber width and the self-tapping screw reinforcement played important roles in terms of the ultimate strengths, ductility, and deformability. Rectangular notched connections with screw reinforcements displayed timber shear failure coupled with brittle failure. With the trapezoidal notch, the ductility of the connections improved, coupled with a decrease in the slip modulus. The self-tapping screw reinforcement for shear timber could greatly improve the ductility performance of the HNS connections. The slip modulus models for the connection with vertical deep notches were provided, which were in agreement with the experimental results.
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Simulation of impact force generated by an ISO tapping machine on a wooden slab using explicit dynamics analysis

https://research.thinkwood.com/en/permalink/catalogue3256
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Lietzén, Jesse
Sormunen, Juho
Pajunen, Sami
Kylliäinen, Mikko
Organization
Tampere University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Impact Sound Insulation
Impact Force
FEM
Explicit Time Integration
LS-DYNA
Tapping Machine
Wooden Floor
Research Status
Complete
Series
Engineering Structures
Summary
Application of simulation tools to compute impact sound insulation properties of wooden floors has raised interests in recent decades. To achieve accurate results from the prediction models, information from force excitation generated by impact sound sources is required. The purpose of our study was to present a validated procedure to determine the non-linear impact force excitation generated by an ISO tapping machine. The method comprised use of finite element method (FEM) and explicit time integration to compute impact force pulse generated by a hammer of the tapping machine. With a post-processing procedure, the force pulses can be converted to present point forces describing the continuous operation of the tapping machine on the floor. To demonstrate the applicability of the method, the finite element model was applied to imitate an experimental situation on a cross-laminated timber (CLT) slab. The model validation showed that the computational model closely predicts the force pulse generated on the CLT slab. Findings from a sensitivity analysis revealed that local properties of the slab were the most important to the simulated impact force pulse. The findings of the analysis are helpful for those developing simulation tools to compute the impact force generated by the tapping machine on wooden floors.
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Structural Performance of Mass Timber Panel-Concrete Composite Floors with Notched Connections

https://research.thinkwood.com/en/permalink/catalogue3122
Year of Publication
2022
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Zhang, Lei
Organization
University of Alberta
Year of Publication
2022
Format
Thesis
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Notched Connection
Discrete Bond Composite Beam Model
Mass Timber Panel
Connection Stiffness
Effective Bending Stiffness
Load-Carrying Capacity
Research Status
Complete
Summary
This thesis focuses on the structural performance of mass timber panel-concrete composite floors with notches. Mass timber panels (MTPs) such as cross-laminated timber, glue-laminated timber, and nail-laminated timber, are emerging construction materials in the building industry due to their high strength, great dimensional stability, and prefabrication. The combination of MTPs and concrete in the floor system offers many structural, economic, and ecological benefits. The structural performance of MTP-concrete composite floors is governed by the shear connection system between timber and concrete. The notched connections made by cutting grooves on timber and filling them with concrete are considered as a structurally efficient and cost-saving connecting solution for resisting shear forces and restricting relative slips between timber and concrete. However, the notched connection design in the composite floors is not standardized and the existing design guidelines are inadequate for MTP-concrete composite floors. To study the structural performance of notched connections and notch-connected composite floors, this thesis presented experimental, numerical, and analytical investigations. Push-out tests were conducted on the notched connections first, and then bending tests and vibration tests were conducted on full-scale composite floors. Finite element models were built for the notched connections to derive the connection shear stiffness. Finally, analytical solutions were developed to predict the internal actions of the composite floors under external loads. This study shows that the structural performance of notched connections is affected by the geometry of the connections and material properties of timber and concrete. The notch-connected MTP-concrete composite floors showed high bending stiffness but were not fully composite. The floors with shallow notches tended to fail in a ductile manner but had lower bending stiffness than floors with deep notches. The composite floors with deep notches, however, often fail abruptly in the concrete notches. By reinforcing the notched connections with steel fasteners, the composite floor can achieve high bending stiffness, high load-carrying capacity, and controlled failure pattern. The proper number and locations of notched connections in the composite floors can be determined from the proposed composite beam model. This thesis presented promising results in terms of the static and dynamic structural performance of notch-connected MTP-concrete composite floors. The test investigations added additional data to the current research body and prompted further evolvement of timber-concrete composite floors. The proposed empirical equations for estimating the connection stiffness and strength and composite beam model for predicting the serviceability and ultimate structural performance of composite floors provide useful tools to analyze the notch-connected MTP-concrete composite floors. The design recommendations for MTP-concrete composite floors with notches are provided in the thesis.
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Timber-concrete composite structural flooring system

https://research.thinkwood.com/en/permalink/catalogue3065
Year of Publication
2022
Topic
Mechanical Properties
Design and Systems
Material
Timber-Concrete Composite
Application
Floors
Author
Estévez-Cimadevila, J.
Martín-Gutiérrez, E.
Suárez-Riestra, F.
Otero-Chans, D.
Vázquez-Rodríguez, J. A.
Organization
Universidade da Coruña
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Design and Systems
Keywords
Timber Flooring System
Mixed Beams
Shear Connector
Research Status
Complete
Series
Journal of Building Engineering
Summary
An integrated solution is presented for the execution of building structures using timber-concrete composite (TCC) sections that make efficient use of the mechanical properties of both materials. The system integrates flooring and shaped prefabricated beams composed of a lower flange of glued laminated timber (GLT) glued to one or more plywood or laminated veneer lumber (LVL) ribs and linked to an upper concrete slab poured in situ. The parts may be prefabricated in T shape (only one rib), in p shape (two ribs), or with multiple ribs to create wider pieces, thereby reducing installation operations. The basis of the system is the timber-concrete shear connection in the form of holes through the ribs, which are filled by the in situ-poured concrete. The connection is complemented with the arrangement of reinforcement bars through the holes. Three test campaigns were undertaken. Shear tests of the timber-concrete connection in 12 test pieces. Shear test along the wood-wood glue line (72 planes tested) and wood -plywood (24 planes tested). Delamination test of the glued planes (24 wood-wood planes and 8 wood-plywood planes). The results indicate a high strength joint, with ductile failure and high composite effect. Likewise, the shear test results along the glue line and the delamination tests show section integrity under demanding hygrothermal conditions. Preliminary sizing curves were developed considering the Gamma Method to evaluate the performance of the system. The results show the possibilities of the system, as pouring the upper slab concrete in situ makes it possible to create continuous semi-rigid joints between the elements. This gives rise to slender flooring structures, light and with high stiffness plane against horizontal forces.
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Vibration performance of timber-concrete composite floor section – verification and validation of analytical and numerical results based on experimental data

https://research.thinkwood.com/en/permalink/catalogue3269
Year of Publication
2022
Topic
Acoustics and Vibration
Material
Timber-Concrete Composite
Application
Floors
Author
Movaffaghi, Hamid
Pyykkö, Johan
Organization
University of Borås
Jönköping University
Uppsala University
Publisher
Taylor&Francis Online
Year of Publication
2022
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Acoustics and Vibration
Keywords
Composite Floor
Fundamental Frequency
RMS Velocity
RMS Acceleration
Finite Element Method
Research Status
Complete
Series
Civil Engineering and Environmental Systems
Summary
Vibration performance of a one-way simply supported timber-concrete composite (TCC) floor section has been studied using analytical as well as numerical methods. Focal points have been verification and validation of results from analytical and numerical calculations of vibration response based on experimental data. For the analytical calculations, floor bending stiffness and vibrational response are determined from methods proposed in the current and revised versions of Eurocode 5. The numerical calculations based on the finite element (FE) method are done using 3D solid elements with orthotropic material parameters. When comparing the results of the FE analysis, better agreement with the experimental data is reached for the fundamental frequency when 3D solid elements are used rather than 3D beam elements. Furthermore, better agreement with the experimental data is reached for RMS acceleration by FE analysis rather than the method based on Eurocode 5. For detailed analysis, the authors suggest performing dynamic FE analysis and calculating vibration response from the TCC floor’s modal responses as eigenmodes and natural eigenfrequencies below 40 Hz. For future studies, it is recommended that the verification of vibration response may be accomplished by applying standard EN 16929.
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Analytical Investigation of the Potential of Hollowcore Mass Timber Panels for Long Span Floor Systems

https://research.thinkwood.com/en/permalink/catalogue3353
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Author
Hull, T.
Lacroix, D.
Organization
University of Waterloo
Publisher
Springer
Year of Publication
2021
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Topic
Mechanical Properties
Keywords
Long Span
Vibration Controlled Span
Conference
Proceedings of the Canadian Society of Civil Engineering Annual Conference 2021
Research Status
Complete
Notes
Page 621
Summary
Mass timber products have shown tremendous potential as sustainable structural components in large building systems. However, challenges occur when open floor plan structures are desired due to conventional flat slab floor systems having difficulties achieving the longer floor span expectations (i.e., exceeding 9 m). This paper investigates the potential of an all-wood solution, namely, hollowcore mass timber (HMT) panels, in meeting the demands of longer spans while also minimizing the use of wood material when compared to a solid slab. A 400 mm deep, 9 m long HMT panel composed of 3-layer cross-laminated timber (CLT) panels as flanges, and glulam beams as webs, is compared to the maximum commonly available CLT and dowel-laminated timber (DLT) alternatives. Two analytical methods and a finite element model are used to determine the effective bending stiffness of the HMT panel, while CSA O86 design procedures are used for the CLT and DLT panels. The effective bending stiffness of the HMT panel between the finite element model and analytical methods ranged from 1.71–1.94 and 1.14–1.29 times greater, despite being 18% and 24% lighter, than the CLT and DLT panels, respectively. Although slightly deeper, the HMT section provided a more efficient use of materials when compared to the solid slab options. The vibration-controlled span limit of the HMT panel was on average 9.8 m, which was 1.8 m and 0.9 m longer than the CLT and DLT panels, respectively. Further areas of study were also identified and will be investigated as part of future work in the broader HMT panel research program.
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Bending performance of cross-laminated timber-concrete composite slabs according to the composite method

https://research.thinkwood.com/en/permalink/catalogue3380
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Author
Baek, Seung-Youp
Song, Yo-Jin
Yu, Seok-Hoon
Kim, Dong-Hyeon
Hong, Soon-I1
Organization
Kangwon National University
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Shear Connection
CFRP
Failure Mode
Research Status
Complete
Series
BioResources
Summary
Bending strength tests were conducted of cross-laminated timber (CLT)-concrete composite slabs according to the shear connection method and carbon fiber reinforced plastic (CFRP) reinforcement. The bending strength of the composite slab that was shear-connected with an epoxy adhesive was 17% higher than that of a composite slab that was shear-connected with a self-tapping screw. In addition, the CLT-concrete slip of the former composite slab was also measured as 20% lower than the latter under the same load, showing a behavior close to that of a full composite. Both shear connection methods generated a failure in a low load-deformation section when there was a defect in the outermost tensile laminae of the CLT. In contrast, the CFRP reinforcement in the tension part of the composite slab suppressed the failure at the defect in the outermost tensile laminae. This reinforcement effect increased the reliability of the bending performance of the composite slab by preventing the failure of the composite slab while in a constant failure mode. Furthermore, the slip of the composite slab decreased 49% after its reinforcement with CFRP, showing a behavior close to that of a full composite.
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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
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
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.
Online Access
Free
Resource Link
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Cross Laminated Timber under Concentrated Compression Loads - Methods of Reinforcement

https://research.thinkwood.com/en/permalink/catalogue2932
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Maurer, Bernhard
Maderebner, Roland
Organization
University of Innsbruck
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Mechanical Properties
Keywords
Multi-storey Buildings
Point-supported Flat Slabs
Reinforcement
System Connector
SPIDER Connector
Punching Test
Research Status
Complete
Series
Engineering Structures
Summary
Point-supported flat slabs made of cross laminated timber (CLT) for multi-storey buildings pose various challenges to structural timber design. One aspect are concentrated compressive loads, which cause stress concentrations in the form of shear and compression perpendicular to the grain at the point supports. The present work deals with this problem and shows a method, how the support area can be reinforced with a system connector. After a specification of the connector, the functionality of this construction element is described on the basis of experimental, numerical and analytical studies for a symmetrical loading. The interaction of the connector with the (CLT) is presented with an anlaytical model and numerical simulations, and evaluated with mechanical tests.
Online Access
Free
Resource Link
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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
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.
Online Access
Free
Resource Link
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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
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
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.
Online Access
Free
Resource Link
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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
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
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.
Online Access
Free
Resource Link
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335 records – page 2 of 17.