American Society of Civil Engineers


In-Plane Experimental Testing of Timber-Concrete Composite Floor Diaphragms


by Michael P. Newcombe, (corresponding author), (Ph.D. Candidate, Dept. of Civil and Natural Resources Engineering, Univ. of Canterbury, Christchurch, New Zealand), Wouter A. van Beerschoten, (Graduate student, Delft Univ. of Technology, Delft, The Netherlands.), David Carradine, (Timber Researcher, Dept. of Civil and Natural Resources Engineering, Univ. of Canterbury, Christchurch, New Zealand.), Stefano Pampanin, (Associate Professor, Dept. of Civil and Natural Resources Engineering, Univ. of Canterbury, Christchurch, New Zealand.), and Andrew H. Buchanan, (Professor, Dept. of Civil and Natural Resources Engineering, Univ. of Canterbury, Christchurch, New Zealand.)

Journal of Structural Engineering, Vol. 136, No. 11, November 2010, pp. 1461-1468, (doi:  http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0000239)

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Document type: Journal Paper
Abstract: Recent advances in multistory timber building design have led to new structural systems that allow open floor plans with large spans between frames and/or walls. Timber-concrete composite (TCC) flooring can achieve the spans required but has the potential to be flexible under diaphragm actions, which can significantly alter the seismic response of a building. In-plane experimental tests on a 3 m by 3 m one-third scale TCC floor were performed using quasi-static earthquake loading simulation. The experimental results indicate that the deformation between the floor and lateral load resisting systems (LLRS) is much greater than the in-plane deformation of the floor diaphragm. Hence, a floor system with similar aspect ratio can be modeled as a single-degree-of-freedom for future structural analyses. Different connections were considered between the floor unit and lateral restraints, which simulate the LLRS. The connection was either timber-to-timber or concrete-to-timber and incorporated screws or nails acting as dowels or inclined at 45°. Each connection type performed differently in terms of stiffness, strength, ductility capacity, and induced damage. Screws that were oriented at 45° to the connection interface were significantly stiffer than fasteners aligned orthogonal to the interface. There was little difference in the initial stiffness for the concrete-to-timber connection compared to the timber-to-timber connection. The testing indicated that a timber-to-timber interface is more desirable because of construction ease and reparability. The in-plane response of the floor system is modeled using finite elements and compared to experimental results. Design recommendations are provided for the cyclic strength of inclined wood fasteners.


ASCE Subject Headings:
Composite materials
Experimentation
Floors
Multi-story buildings
Timber construction

Author Keywords:
Multistory
Timber
Floor diaphragm
Timber-concrete composite