Composite Wood-Concrete Beams Using Utility Poles: Time-Dependent Behavior
Publication: Journal of Structural Engineering
Volume 137, Issue 6
Abstract
This paper describes the behavior of wood-concrete composite beams in which the wood layer is composed of recycled utility poles. Two full-scale laboratory specimens of -mm (295-in.) span were constructed, with the concrete slab cast on the timber poles left unshored. The connection was obtained by cutting six notches in the timber poles. A threaded steel dowel is placed in each notch extending through both layers with a nut on the bottom of the beam that can be tightened once the concrete has cured. Since the material in each layer exhibits a time-dependent response, it is necessary to examine the effects of sustained loading. After 28 days of initial curing of the concrete layer during which the midspan deflection was monitored, both beams were subjected to the service load to estimate the composite efficiency. The beams were very stiff and values of 96% and 98% were obtained, respectively, demonstrating the high efficiency of the notched connection system used. A comparison was made with results obtained in the literature for ramp load tests of two similar specimens, which had exhibited composite efficiencies of about 94% and 96%, respectively. A sustained load of approximately 11% of the estimated static ultimate load capacity was then applied to one of the specimens, which was monitored over time. The applied load resulted in a midspan moment of () while the calculated ultimate capacity corresponded to a midspan moment of (). The final deflection was found to increase to 44.4 mm (1.75 in.) after 256 days, which was more than twice the initial elastic deflection owing to the application of the dead and live loads. The deflection attributable to the dead load was 19.1 mm (0.75 in.), and the deflection attributable to the live load was 2.54 mm (0.10 in.). An existing one-dimensional (1D) finite-element program was utilized to predict the time-dependent deflection at the end of a 50-year service life. The comparison with experimental results showed good approximation, particularly for the midspan deflection. The software predicted a 54-mm (2.14-in.) midspan deflection at the end of a 50-year service life, corresponding to of the span. This was sufficiently high to suggest that either larger cross-section and/or precambering of the wood layer could be needed when the serviceability limit state of maximum deflection in the long-term is a required performance criterion.
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Acknowledgments
Xcel Energy of Colorado provided the utility poles (salvaged from roadway expansion projects in Fort Collins) for use in this project as well as for past and future needs. The U.S. DOT has provided support for the past and ongoing studies related to possible application in bridges. That funding was via the Mountain Plains Consortium, which is federally sponsored through the University Transportation Centers Program. The contents of this paper reflect the views of the writers only, and the mentioned agencies assume no liability for the contents or use thereof.
References
American Concrete Institute (ACI). (1982). “Prediction of creep, shrinkage, and temperature effects in concrete structures.” ACI 209-82, Farmington Hills, MI.
American Concrete Institute (ACI). (2005). “Building code requirements for structural concrete and commentary.” ACI 318-05, Farmington Hills, MI.
American Forest and Paper Association (AFPA). (2005). “National design specification for wood construction.” Leesburg, VA.
ASCE. (2009). “2009 report card for America’s infrastructure.” 〈http://www.infrastructurereportcard.org/fact-sheet/bridges〉 (May 19, 2010).
ASTM (1999a). “Standard practice for making and curing concrete test specimens in the laboratory.” ASTM C192-98, West Conshohocken, PA.
ASTM. (1999b). “Standard test method for compressive strength of cylindrical concrete specimens.” ASTM C39-96, West Conshohocken, PA.
Balogh, J., Fragiacomo, M., Gutkowski, R. M., and Fast, R. S. (2008). “Influence of repeated and sustained loading on the performance of layered wood-concrete composite beams.” J. Struct. Eng., 134(3), 430–439.
Balogh, J., Wieligmann, M., Gutkowski, R., and Haller, P. (2002). “Stress-strain behavior of connections for partially composite wood-concrete floors and deck systems.” Proc. of the 2nd Material Specialty Conf. of the Canadian Society for Civil Engineering, Canadian Society for Civil Engineering, Montréal.
Brown, K. (1998). “Testing of a shear key/anchor in layered wood/concrete beams.” M.S. thesis, Colorado State Univ., Fort Collins, CO.
Capozucca, R. (1998). “Bond stress system of composite concrete-timber beams.” Mater. Struct., 31(9), 634–640.
Ceccotti, A. (2002). “Composite concrete-timber structures.” Prog. Struct. Eng. Mater., 4(3), 264–275.
Chassagne, P., Bou Saïd, E., Jullien, F. J., and Galimard, P. (2006). “Three dimensional creep model for wood under variable humidity—Numerical analyses at different material scales.” Mech. Time-Depend. Mater., 9(4), 1–24.
Clouston, P., Bathon, L., and Schreyer, A. (2005). “Shear and bending performance of a novel wood-concrete composite system.” J. Struct. Eng., 131(9), 1404–1412.
Comité Européen de Normalisation (CEN). (2004). “Eurocode 5—Design of timber structures—Part 1-1: General rules and rules for buildings.” EN 1995-1-1, Brussels, Belgium.
Comité Européen du Béton—Fédération Internationale de la Précontrainte (CEB-FIP). (1990). “Evaluation of the time dependent behaviour of concrete.” CEP-FIP Model Code for Concrete Structures, Bulletin d’Information No. 199, Lausanne, Switzerland.
Deam, B. L., Fragiacomo, M., and Buchanan, A. H. (2007). “Connections for composite concrete slab and LVL flooring systems.” Mater. Struct., 41(3), 495–507.
Dias, A. M. P. G. (2005). “Mechanical behaviour of timber-concrete joints.” Ph.D. thesis, Univ. of Coimbra, Portugal.
Etournaud, P. (1998). “Load tests of composite wood-concrete deckings under point loads.” M.S. thesis, Colorado State Univ., Fort Collins, CO.
Fast, R. (2003). “Durability studies of layered wood-concrete composite connections and beams.” M.S. thesis, Colorado State Univ., Fort Collins, CO.
Fragiacomo, M. (2005). “A finite element model for long-term analysis of timber-concrete composite beams.” Struct. Eng. Mech., 20(2), 173–189.
Fragiacomo, M. (2006). “Long-term behavior of timber-concrete composite beams. II: Numerical analysis and simplified evaluation.” J. Struct. Eng., 132(1), 23–33.
Fragiacomo, M., Amadio, C., and Macorini, L. (2004). “A finite element model for collapse and long-term analysis of steel-concrete composite beams.” J. Struct. Eng., 130(3), 489–497.
Fragiacomo, M., Amadio, C., and Macorini, L. (2006). “Short- and long-term performance of the ‘Tecnaria’ stud connector for timber-concrete composite beams.” Mater. Struct., 40(10), 1013–1026.
Fragiacomo, M., and Ceccotti, A. (2006). “Long-term behavior of timber-concrete composite beams. I: Finite element modeling and validation.” J. Struct. Eng., 132(1), 13–22.
Fragiacomo, M., Gutkowski, R. M., Balogh, J., and Fast, R. S. (2007). “Long-term behaviour of wood-concrete composite floor/deck systems with shear key connection detail.” J. Struct. Eng., 133(9), 1307–1315.
Fritz-Pak Concrete Admixtures. (2005). “Supercizer 7 high performance super plasticizer.” 〈http://www.fritzpak.com/pdfs/pb115_supercizer7.pdf〉 (Jun. 2008)
Hanhijärvi, A. (1995). “Deformation kinetics based rheological model for the time-dependent and moisture induced deformation of wood.” Wood Sci. Technol., 29(3), 191–200.
Gutkowski, R., Balogh, J., Natterer, J., Brown, K., Koike, E., and Etournaud, P. (2000). “Laboratory tests of composite wood-concrete beam and floor specimens.” Proc. of the World Conf. on Timber Engineering—2000, Univ. of British Columbia, Vancouver, BC.
Gutkowski, R., Brown, K., Shigidi, A., and Natterer, J. (2008). “Laboratory tests of composite wood-concrete beams.” Constr. Build. Mater., 22(6), 1059–1066.
Gutkowski, R., Fast, R., Balogh, J., and Fragiacomo, M. (2006). “Time-dependent performance of notched wood-concrete composite beams.” Proc. 11th Int. Conf. and Exhibition in Structural Faults and Repair, Edinburgh, Scotland.
Kuhlmann, U., and Michelfelder, B. (2004). “Grooves as shear connectors in timber-concrete composite structures.” Proc. of the 8th World Conf. on Timber Engineering, WCTE 2004, Vol. 1, Lahti, Finland, 301–306.
LeBorgne, M. (2007). “Analysis of wood-concrete beams incorporating recycled utility poles.” M.S. thesis, Colorado State Univ., Fort Collins, CO.
LeBorgne, M., and Gutkowski, R. M. (2008). “Load testing of wood-concrete beams incorporating recycled utility poles.” Rep. No. 08-197, Mountain-Plains Consortium, North Dakota State Univ., Fargo, ND.
LeBorgne, M. R., and Gutkowski, R. M. (2010). “Effects of various admixtures and shear keys in wood-concrete composite beams.” Constr. Build. Mater., 24, 1730–1738.
Lukaszewska, E., Johnsson, H., and Fragiacomo, M. (2008). “Performance of connections for prefabricated timber-concrete composite floors.” Mater. Struct., 41(9), 1533–1550.
Miller, N. (2009). “Long-term and repeated load behavior of wood-concrete composite beams incorporating utility poles.” M.S. thesis, Colorado State Univ., Fort Collins, CO.
Mungwa, M. S., Jullien, J. F., Foudjet, A., and Henteges, G. (1999). “Experimental study of a composite wood-concrete beam with the INSA-Hilti new flexible shear connector.” Constr. Build. Mater., 13(7), 371–382.
Natterer, J., Hamm, J., and Favre, P. (1996). “Composite wood-concrete floors in multi-story buildings.” Proc. of the Int. Wood Engineering Conf., New Orleans, 3431–3435.
Pault, J. (1977). “Composite action in Glulam timber bridge systems.” M.S. thesis, Colorado State Univ., Fort Collins, CO.
Schänzlin, J. (2003). “Time dependent behavior of composite structures of board stacks and concrete.” Ph.D. thesis, Univ. of Stuttgart (in German).
Steinberg, E., Selle, R., and Faust, T. (2003). “Connectors for timber-lightweight concrete composite structures.” J. Struct. Eng., 129(11), 1538–1545.
To, L. (2009). “3D finite element modeling of time-dependent behavior of composite wood-concrete beams.” Ph.D. thesis, Colorado State Univ., Fort Collins, CO.
To, L., Fragiacomo, M., Balogh, J., and Gutkowski, R. M. (2011). “Long-term load test of a wood-concrete composite beam.” Proc. ICE Struct. Build., 162(SB2), 117–129.
Toratti, T. (1992). “Creep of timber beams in a variable environment.” Rep. No. 31, Helsinki Univ. of Technology, Helsinki, Finland.
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 137 • Issue 6 • June 2011
Pages: 625 - 634
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Jan 24, 2010
Accepted: Aug 8, 2010
Published online: Aug 24, 2010
Published in print: Jun 1, 2011
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