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Thin Topping Timber-Concrete Composite Floors

https://research.thinkwood.com/en/permalink/catalogue902
Year of Publication
2014
Topic
Design and Systems
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Skinner, Jonathan
Organization
University of Bath
Year of Publication
2014
Country of Publication
United Kingdom
Format
Thesis
Material
Timber-Concrete Composite
Application
Floors
Topic
Design and Systems
Mechanical Properties
Keywords
Stiffness
Vibration Response
Topping Thickness
Screws
shear connectors
Static Loads
Cyclic Loads
Short-term
Bending Tests
Language
English
Research Status
Complete
Summary
A timber-concrete composite (TCC) combines timber and concrete, utilising the complementary properties of each material. The composite is designed in such a way that the timber resists combined tension and bending, whilst the concrete resists combined compression and bending. This construction technique can be used either in new build construction, or in refurbishment, for upgrading existing timber structures. Its use is most prolific in continental Europe, Australasia, and the United States of America but has yet to be widely used in the United Kingdom. To date, the topping upgrades used have been 40mm thick or greater. Depending on the choice of shear connection, this can lead to a four-fold increase in strength and stiffness of the floor. However, in many practical refurbishment situations, such a large increase in stiffness is not required, therefore a thinner topping can suffice. The overarching aim of this study has been to develop a thin (20mm) topping timber-concrete composite upgrade with a view to improving the serviceability performance of existing timber floors. Particular emphasis was given to developing an understanding of how the upgrade changes the stiffness and transient vibration response of a timber floor. Initially, an analytical study was carried out to define an appropriate topping thickness. An experimental testing programme was then completed to: characterise suitable shear connectors under static and cyclic loads, assess the benefit of the upgrade to the short-term bending performance of panels and floors, and evaluate the influence of the upgrade on the transient vibration response of a floor. For refurbishing timber floors, a 20mm thick topping sufficiently increased the bending stiffness and improved the transient vibration response. The stiffness of the screw connectors was influenced by the thickness of the topping and the inclination of the screws. During the short-term bending tests, the gamma method provided a non-conservative prediction of composite bending stiffness. In the majority of cases the modal frequencies of the floors tested increased after upgrade, whilst the damping ratios decreased. The upgrade system was shown to be robust as cracking of the topping did not influence the short-term bending performance of panels. Thin topping TCC upgrades offer a practical and effective solution to building practitioners, for improving the serviceability performance of existing timber floors.
Online Access
Free
Resource Link
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