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Experimental Investigation on the Long-Term Behaviour of Prefabricated Timber-Concrete Composite Beams with Steel Plate Connections

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

https://research.thinkwood.com/en/permalink/catalogue310
Year of Publication
2015
Topic
Connections
Mechanical Properties
Serviceability
Moisture
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Author
Hailu, Mulugheta
Organization
University of Technology Sydney
Year of Publication
2015
Country of Publication
Australia
Format
Thesis
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Topic
Connections
Mechanical Properties
Serviceability
Moisture
Keywords
Serviceability Limit States
Deflection
Long-term Behaviour
Creep
Mechanosorption
Eurocode
Language
English
Research Status
Complete
Summary
The objectives and scope of this study are to conduct long-term experimental test on timber-concrete composite beams, analyse the results to determine the creep coefficient of the composite system and compare the experimental results with the analytical solutions in accordance with Eurocode 5, in which the effective modulus method is used to account the effect of creep. To achieve the aforementioned objectives, a long-term laboratory investigation was started in August 2010 on four 5.8m span TCC beams with four different connector types. The specimens have been under sustained loads of 1.7kPa and subjected to a cyclic humidity conditions whilst the temperature remains quasi constant (22 °C). During the test, the mid-span deflection, moisture content of the timber beams and relative humidity of the air are continuously monitored. The long-term test is still continuing, two TCC beams were unloaded and tested to failure after 550 days, while the other two TCC beams are still being monitored and this report included experimental results up to the first 1400 days only. The long-term investigation on the two timber only composite floor beams commenced on March 2013 and the results are reported for the first 800 days from their commencement.
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Post-Tensioned Timber Connections, Experimental Analysis of the Long Term Behavior

https://research.thinkwood.com/en/permalink/catalogue527
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Wanninger, Flavio
Frangi, Andrea
Year of Publication
2014
Country of Publication
Canada
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Climate
Post-Tensioning
Relative Humidity
Temperature
Long-term Behaviour
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
To estimate the loss of tendon force for a post-tensioned timber connection a series of tests are being conducted at the ETH in Zurich. Several post-tensioned specimens are being observed in different climate conditions. One set of specimens is in a climate chamber, where the relative humidity and temperature are kept constant. The second set of test specimens is positioned in an uncontrolled environment, where temperature and relative humidity change daily. The two environments allow estimating the influence of changes in relative humidity and temperature on the loss rate of tendon force. First results show that the relative humidity influences this rate, making it a key variable to estimate the total loss in post-tensioning force during the lifetime of a building.
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Review on Long-Term Behaviour of Timber-Concrete Composite Floors

https://research.thinkwood.com/en/permalink/catalogue904
Year of Publication
2013
Topic
Serviceability
Material
Timber-Concrete Composite
Application
Floors
Author
Khorsandnia, Nima
Valipour, Hamid
Shrestha, Rijun
Gerber, Christophe
Crews, Keith
Year of Publication
2013
Country of Publication
Australia
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Serviceability
Keywords
Long-term Behaviour
Temperature
Relative Humidity
Language
English
Conference
Australasian Conference on the Mechanics of Structures and Materials
Research Status
Complete
Notes
December 11-14, 2012, Sydney, Australia
Summary
Timber-concrete composite (TCC) beams are made up two materials, i.e. wood and concrete, which exhibit different behaviours under long-term loading. The time-dependent behaviour of TCC beam is not only affected by the long-term load but also driven by the variation of the environmental conditions such as temperature and relative humidity. In particular, the maximum deflection under service loads may govern the design requirement for medium to long span TCC beams subjected to heavy environmental conditions. For such structures, application of simplified methods adopted by different codes may lead to significant errors. Hence investigating the long-term behaviour of TCC beams subject to variable environmental condition is of great importance for designers and researchers. In this paper the research undertaken on long-term behaviour of TCC floors is critically reviewed and the recent findings are highlighted. The most important references in the literature were selected to provide more depth into the time-dependent performance of TCC structure.
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Structural Tests of Concrete Composite-Cross-Laminated Timber Floors

https://research.thinkwood.com/en/permalink/catalogue2830
Year of Publication
2017
Topic
Connections
Mechanical Properties
Serviceability
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Decking
Author
Higgins, Christopher
Barbosa, R. Andre
Blank, Curtis
Organization
Oregon State University
Publisher
Oregon State University
Year of Publication
2017
Country of Publication
United States
Format
Report
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Decking
Topic
Connections
Mechanical Properties
Serviceability
Keywords
Bending Behaviour
Shear Connection
Long-term Behaviour
TCC
Orthrotropic Plates
Language
English
Research Status
Complete
Summary
Experimental tests of a composite concrete-cross-laminated timber (CLT) floor system were conducted. The floor system was constructed with 5-ply CLT panels (6.75 in. thick) made composite with a 2.25 in. thick reinforced concrete topping slab. Four series of tests were performed using different specimen configurations and laboratory testing methods. Tests included: (1) Comparative one-way bending tests (CB) to evaluate the performance of alternative shear connectors used to join the concrete slab to the CLT panel; (2) Orthotropic stiffness and strength tests (OS) to evaluate the elastic orthotropic stiffness of the deck system and provide strength results for weak-axis bending and negative moment strength; (3) Full-scale system performance tests (FS) of a continuous floor span to establish strength at realistic span lengths and the influence of continuity; and (4) Long-term deformation tests (LT) to investigate creep deflections of the composite concrete-CLT floor system considering positive and negative bending influences. Results include overall strength, elastic stiffness values, deformation capacity, slip deformations along the concrete-CLT interface, predicted neutral axis locations in the composite concrete-CLT systems, and connection deformations.
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