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Flexural behaviour of a new timber-concrete composite structural flooring system. Full scale testing

https://research.thinkwood.com/en/permalink/catalogue3314
Year of Publication
2023
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Martín-Gutiérrez, Emilio
Estévez-Cimadevila, Javier
Suárez-Riestra, Félix
Otero-Chans, Dolores
Organization
University of Coruña
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Timber Flooring System
Flexural Behaviour
Four-point Bending Test
Research Status
Complete
Series
Journal of Building Engineering
Summary
Timber-concrete composite systems are a high-performance alternative for building floors, of great interest in the current context of environmental concerns. Looking for a more eco-friendly solution, the paper presents a new flooring system with a wood-concrete connection that does not require adhesives or special metal elements. Four-point bending tests were performed on TCC flooring samples with a span of 6.0, 7.2 and 8.4 m. Its cross section was a prefabricated piece in the shape of an inverted T made up of a lower glulam flange, glued together with a central plywood rib with aligned holes in its upper part that go through the entire thickness of the plywood. The set was completed with a top layer of poured-in-place concrete. The connection between both materials is achieved by penetrating the concrete into the rib holes. Additionally, corrugated steel bars were placed through said holes to achieve ductile behaviour. In all cases, a slenderness ratio of L/24 was used. The experimental results showed that the lowest value of ultimate load obtained was 4.3 times higher than the total service load estimated for a building for public use (9 kN/m2). The maximum deflection of the total load was between L/573 and L/709 for the loads corresponding to a building for public use (9 kN/m2) and between L/1069 and L/1340 for the case of residential type building (5 kN/m2). An analysis of the effects of vibrations in the service limit state in relation to user comfort has been included. The results indicate that the system satisfies the requirements for the intended uses. Consequently, the proposed solution shows its effectiveness both in terms of strength and stiffness for the construction of light floors, being easy to build and having high performance.
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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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Experimental and theoretical investigation on shear performances of glued-in perforated steel plate connections for prefabricated timber–concrete composite beams

https://research.thinkwood.com/en/permalink/catalogue3373
Year of Publication
2023
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Beams
Floors
Author
Yang, Huifeng
Lu, Yan
Ling, Xiu
Tao, Haotian
Shi, Benkai
Organization
Nanjing Tech University
Southeast University
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
Timber-Concrete Composite
Application
Beams
Floors
Topic
Mechanical Properties
Keywords
Glued-in Perforated Steel Plate
Prefabricated Concrete Slab
Slip Modulus
Experimental Study
Research Status
Complete
Series
Case Studies in Construction Materials
Summary
Glued-in perforated steel plate (GIPSP) connections demonstrate significant shear strength and high slip modulus. Consequently, they indicate substantial potential for application in timber–concrete composite (TCC) structures according to the emerging tendencies in high-storey and large-span buildings. However, the application pattern in prefabricated TCC structures and the theoretical analysis of the shear performances of GIPSP connections are highly deficient. This hinders the application of this type of shear connection. In this study, the shear performances of GIPSP connections were evaluated using push-out tests. Ten groups of push-out specimens with different steel plate numbers, steel plate lengths, and concrete slab types were tested. The concrete slab types investigated in the experiments included a prefabricated concrete slab and cast-in-situ concrete slab. The experimental results were discussed in terms of the failure mode, load-carrying capacity, and slip modulus. The theoretical models for the load-carrying capacity related to the associate failure mode were discussed based on an analysis of the failure mechanisms. In addition, design proposals with regard to the load-carrying capacity and slip modulus of the GIPSP connection were presented. The research results can provide design guidance for TCC beams using GIPSP connections and prefabricated concrete slabs.
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Experimental analysis of timber-concrete composite behaviour with synthetic fibres

https://research.thinkwood.com/en/permalink/catalogue3396
Year of Publication
2023
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Buka-Vaivade, K
Serdjuks, D
Zvirina, D
Pakrastins, L
Organization
Riga Technical University
Publisher
IOP Publishing
Year of Publication
2023
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Synthetic Fibre
Bending Test
Conference
5th International Conference: Innovative Materials, Structures and Technologies (IMST 2022)
Research Status
Complete
Series
Journal of Physics: Conference Series
Summary
With the growing importance of the principles of sustainable construction, the use of load-bearing timber-concrete composite structures is becoming increasingly popular. Timber-concrete composite offers wider possibilities for the use of timber in construction, especially for large-span structures. The most significant benefit from combining these materials can be obtained by providing a rigid connection between the timber and concrete layers, which can be obtained by the adhesive timber-to-concrete connection produced by the proposed stone chips method. A sustainable solution involves the abandonment of steel longitudinal reinforcement. The use of such a solution in practice is often associated with fears of a fragile collapse. Therefore, the issue of how to increase the safety factor of the proposed material is topical now. The experimental investigation is made to determine the effect of synthetic fibre use on timber-concrete composite behaviour by testing a series of timber-concrete composite specimens with and without fibres in the concrete layer. The obtained results show that adding 0.5 % of synthetic macro fibres allows to abandon the use of longitudinal steel reinforcement and prevents the formation of large cracks in concrete and the disintegration of the concrete layer in case of collapse.
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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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Development of Creep Deformations during Service Life: A Comparison of CLT and TCC Floor Constructions

https://research.thinkwood.com/en/permalink/catalogue2955
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Author
Binder, Eva
Derkowski, Wit
Bader, Thomas
Organization
Linnæus University
Editor
Brandner, Reinhard
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Serviceability Limit State
Gamma Method
Linear Viscoelasticity
Research Status
Complete
Series
Buildings
Summary
Cross-laminated timber (CLT) slabs in residential buildings need additional weight, e.g., in the form of screeds or gravel layers, to fulfill the criterion for the highest impact-sound class. The additional mass is, however, not exploited for the load bearing behavior, but adds additional weight and leads to an increased height of the floor construction. In this study, such a CLT floor construction with a construction height of 380 mm is compared with a composite slab consisting of a CLT plate with a concrete layer on top with a floor construction height of 330 mm. The timber concrete composite (TCC) slab has a different creep behavior than the CLT slab. Thus, the development of the time-dependent deflections over the service life are of interest. A straightforward hybrid approach is developed, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behavior. The introduced approach allows to investigate load redistribution between the layers of the composite structure and the evolution of the deflection of the slab during the service life. The investigated slab types show a similar deflection after 50 years, while the development of the deflections over time are different. The CLT slab has a smaller overall stiffness at the beginning but a smaller decrease in stiffness over time than the investigated TCC slab.
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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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CLT Diaphragm Design for Wind and Seismic Resistance

https://research.thinkwood.com/en/permalink/catalogue2967
Year of Publication
2022
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Breneman, Scott
McDonnell, Eric
Tremayne, Donovan
Houston, Jonas
Gu, Mengzhe
Zimmerman, Reid
Montgomery, Graham
Organization
WoodWorks
Holmes
KPFF Consulting Engineers
Timberlab
Publisher
WoodWorks
Year of Publication
2022
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Seismic
Keywords
Diaphragm
Shear Capacity
Diaphragm Flexibility
Panel-to-Panel Connections
Research Status
Complete
Summary
Cross-laminated timber (CLT) has become increasingly prominent in building construction and can be seen in buildings throughout the world. Specifically, the use of CLT floor and roof panels as a primary gravity force-resisting component has become relatively commonplace. Now, with availability of the 2021 Special Design Provisions for Wind and Seismic (SDPWS 2021) from the American Wood Council (AWC), U.S. designers have a standardized path to utilize CLT floor and roof panels as a structural diaphragm. Prior to publication of this document, projects typically had to receive approval to use CLT as a structural diaphragm on a case-by-case basis from the local Authority Having Jurisdiction (AHJ). This paper highlights important provisions of SDPWS 2021 for CLT diaphragm design and recommendations developed by the authors in the upcoming CLT Diaphragm Design Guide, based on SDPWS 2021.
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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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Cross-Laminated Timber Floor: Analysis of the Acoustic Properties and Radiation Efficiency

https://research.thinkwood.com/en/permalink/catalogue3018
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Granzotto, Nicola
Marzi, Arianna
Gasparella, Andrea
Organization
Free University of Bozen
Editor
Vasques, César M. A.
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Acoustic Characterization
Sound Radiation Efficiency
Research Status
Complete
Series
Applied Sciences
Summary
Cross-Laminated Timber (CLT) is a building technology that is becoming increasingly popular due to its sustainable and eco-friendly nature, as well as its availability. Nevertheless, CLT presents some challenges, especially in terms of impact noise and airborne sound insulation. For this reason, many studies focus on the vibro-acoustic behavior of CLT building elements, to understand their performance, advantages and limitations. In this paper, a 200 mm CLT floor has been characterized in the laboratory, according to ISO standards, by three noise sources: dodecahedron, standard tapping machine and rubber ball. In order to understand the vibro-acoustic behavior of the CLT floor, measurements through the analysis of sound pressure levels and velocity levels, measured by dedicated sensors, were performed. Analysis was carried out in order to understand what is prescribed by the prediction methods available in the literature and by the simulation software. Then, a specific prediction law for the CLT floor under investigation was derived. Finally, an analysis on sound radiation index is provided to complete the vibro-acoustic study.
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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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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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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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Cost Factor Analysis for Timber–Concrete Composite with a Lightweight Plywood Rib Floor Panel

https://research.thinkwood.com/en/permalink/catalogue3100
Year of Publication
2022
Topic
Cost
Material
Timber-Concrete Composite
Application
Floors
Author
Buka-Vaivade, Karina
Serdjuks, Dmitrijs
Pakrastins, Leonids
Organization
Riga Technical University
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Cost
Keywords
Adhesive Connection
Plywood Rib Panel
Floor Vibrations
Rigid Connection
Fibre Reinforced Concrete
Research Status
Complete
Series
Buildings
Summary
With the growing importance of the principle of sustainability, there is an increasing interest in the use of timber–concrete composite for floors, especially for medium and large span buildings. Timber–concrete composite combines the better properties of both materials and reduces their disadvantages. The most common choice is to use a cross-laminated timber panel as a base for a timber–concrete composite. But a timber–concrete composite solution with plywood rib panels with an adhesive connection between the timber base and fibre reinforced concrete layer is offered as the more cost-effective constructive solution. An algorithm for determining the rational parameters of the panel cross-section has been developed. The software was written based on the proposed algorithm to compare timber–concrete composite panels with cross-laminated timber and plywood rib panel bases. The developed algorithm includes recommendations of forthcoming Eurocode 5 for timber–concrete composite design and an innovative approach to vibration calculations. The obtained data conclude that the proposed structural solution has up to 73% lower cost and up to 71% smaller self-weight. Thus, the proposed timber–concrete composite construction can meet the needs of society for cost-effective and sustainable innovative floor solutions.
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Behavior of timber-concrete composite with defects in adhesive connection

https://research.thinkwood.com/en/permalink/catalogue3108
Year of Publication
2022
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Buka-Vaivade, Karina
Serdjuks, Dmitrijs
Organization
Riga Technical University
Publisher
Elsevier
Year of Publication
2022
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Adhesive Connection
Rigid Connection
Conference
ICSI 2021 The 4th International Conference on Structural Integrity
Research Status
Complete
Series
Procedia Structural Integrity
Summary
Rigid timber to concrete connection is the most effective solution for timber-concrete composite members subjected to the flexure which provides full composite action and better structural behaviour. One of the most used technologies to produce glued connection of the timber-concrete composite is “dry” method, which includes gluing together of timber and precast concrete slab. This technique has high risk of forming a poor-quality rigid connection in timber-concrete composite, and there are difficulties in controlling the quality of the glued connection. The effect of the non-glued areas in connection between composite layers on the shear stresses and energy absorption were investigated by finite element method and laboratorian experiment. Three timber-concrete composite panels in combination with carbon fibre reinforced plastic composite tapes in the tension zone with the span 1.8 m were statically loaded till the failure by the scheme of three-point bending. Mid-span displacements were measured in the bending test. One specimen was produced by dry method, by gluing together cross-laminated timber panel and prefabricated concrete panel. Timber-concrete qualitative connection of the other two specimens was provided by the granite chips, which were glued on the surface of the cross-laminated timber by epoxy, and then wet concrete was placed. Dimensions of the crushed granite pieces changes within the limits from 16 to 25 mm. The investigated panel with different amount and sizes of non-glued areas in the timber to concrete connection was numerically modelled. Obtained results shown, that the increase of shear stresses is influenced not so much by a total amount of non-glued areas, but by the size of the individual defective areas. Moreover, large non-glued areas significantly reduce the energy absorption of elements subjected to the flexure, which was observed experimentally for defective panel produced by the classical dry method with almost 4 times larger mid-span displacements than for panel with full composite action provided by the proposed production technology of the timber to concrete rigid connection. So, the proposed technology based on the use of granite chips, provides a high-quality connection between timber and concrete layers, with insignificant ration between possible defect and total connection surface area, which is equal to the area of one granite chips edge.
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Analytical Procedure for Timber-Concrete Composite (TCC) System with Mechanical Connectors

https://research.thinkwood.com/en/permalink/catalogue3119
Year of Publication
2022
Topic
Design and Systems
Material
Timber-Concrete Composite
Application
Floors
Author
Mirdad, Md Abdul Hamid
Khan, Rafid
Chui, Ying Hei
Organization
University of Illinois at Urbana-Champaign
University of Alberta
Editor
Tullini, Nerio
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Design and Systems
Keywords
Mechanical Connectors
Progressive Yielding
Effective Bending Stiffness
Deflection
Vibration
Research Status
Complete
Series
Buildings
Summary
In the construction of modern multi-storey mass timber structures, a composite floor system commonly specified by structural engineers is the timber–concrete composite (TCC) system, where a mass timber beam or mass timber panel (MTP) is connected to a concrete slab with mechanical connectors. The design of TCC floor systems has not been addressed in timber design standards due to a lack of suitable analytical models for predicting the serviceability and safety performance of these systems. Moreover, the interlayer connection properties have a large influence on the structural performance of a TCC system. These connection properties are often generated by testing. In this paper, an analytical approach for designing a TCC floor system is proposed that incorporates connection models to predict connection properties from basic connection component properties such as embedment and withdrawal strength/stiffness of the connector, thereby circumventing the need to perform connection tests. The analytical approach leads to the calculation of effective bending stiffness, forces in the connectors, and extreme stresses in concrete and timber of the TCC system, and can be used in design to evaluate allowable floor spans under specific design loads and criteria. An extensive parametric analysis was also conducted following the analytical procedure to investigate the TCC connection and system behaviour. It was observed that the screw spacing and timber thickness remain the most important parameters which significantly influence the TCC system behaviour.
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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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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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Experimental and numerical investigations of two-way LVL–concrete composite plates with various support conditions

https://research.thinkwood.com/en/permalink/catalogue3138
Year of Publication
2022
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Author
Jaaranen, Joonas
Fink, Gerhard
Organization
Aalto University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Two-way Plate
Experimental Modal Analysis
Static Load Test
Finite Element Modelling
Research Status
Complete
Series
Engineering Structures
Summary
Design of modern timber floors is often governed by the vibration serviceability requirements. One way to improve vibration serviceability is through the design of two-way floor systems. In this paper, the behaviour of two-way LVL–concrete composite plates and a plate strip is investigated experimentally, with an emphasis on the performance of proposed dovetail joint for connecting the adjacent LVL panels. The investigations consist of the experimental modal analysis and static load deformation tests, performed under multiple support conditions. The results show a significant two-way action, indicated by about 45% higher fundamental natural frequency when four edges are supported instead of two. The point load deflection in the centre of the plate was reduced of about 9%. Furthermore, a numerical model for two-way TCC plates was developed and results show a wide agreement with the experimental behaviour, except for discrepancies related to deflections on the plate edge. The results from the experimental and numerical investigations indicate that the dovetail joint can produce a stiff connection, such that the LVL layer could be regarded as continuous in the connected direction.
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