Fire Design of Timber-Concrete Composite Slabs with Screwed Connections
Publication: Journal of Structural Engineering
Volume 136, Issue 2
Abstract
The structural behavior of timber-concrete composite slabs is mainly governed by the shear connection between timber and concrete. When a timber-concrete composite structure is exposed to fire, it is of particular importance to know the changes in stiffness and strength that the shear connection is subjected to. For the calculation of the fire resistance of timber-concrete composite slabs a simplified design method was developed on the basis of the calculation model for mechanically jointed beams with flexible elastic connection given in EN 1995-1-1 and the reduced cross section method given in EN 1995-1-2. The effects of temperature on the mechanical properties of timber, concrete, and connection are taken into account by modification factors . For the strength and stiffness properties of the screwed connections simplified formulae for the calculation of the modification factors were developed, based on the results of an extensive experimental study on the fire behavior of the screwed connections. The modification factors were expressed as a function of the side cover of the connections. In this way the temperature in the timber member does not need to be determined, making the calculation of the strength and stiffness properties of the screwed connection in fire much easier for the designer. The paper first describes and discusses the behavior and modeling of the screwed connection in fire, and then the simplified design method developed for the calculation of the fire resistance of timber-concrete composite slabs with screwed connections is presented. Finally, the result of the calculation method is compared to the result of a full-scale fire test.
Get full access to this article
View all available purchase options and get full access to this article.
References
Ahmadi, B. H., and Saka, M. P. (1993). “Behavior of composite timber-concrete floors.” J. Struct. Eng., 119(11), 3111–3130.
Blass, H. J., and Schlager, M. (1997). “Connections for timber-concrete-composite structures.” Proc., Int. Conf. on Composite Construction—Convectional and Innovative, IABSE, Zurich, Switzerland, Innsbruck, Austria, 169–174.
Buchanan, A. H. (2000). “Fire performance of timber construction.” Prog. Struct. Eng. Mater., 2, 278–289.
Ceccotti, A. (1995). “Timber-concrete composite structures.” STEP 2: Timber engineering, Paper E13, Centrum Hout, The Netherlands, 1–12.
Dias, A. M. P. G., Lopes, S. M. R., Van de Kuilen, J. W. G., and Cruz, H. M. P. (2007). “Load-carrying capacity of timber-concrete joints with dowel-type fasteners.” J. Struct. Eng., 133(5), 720–727.
European Committee for Standardisation (CEN). (1999). “Timber structures—Glued laminated timber—Strength classes and determination of characteristic values.” EN 1194, Brussel, Belgium.
European Committee for Standardisation (CEN). (2002). “Eurocode—Basis of structural design.” EN 1990, Brussel, Belgium.
European Committee for Standardisation (CEN). (2004a). “Eurocode 5—Design of timber structures. Part 1-1: General—Common rules and rules for buildings.” EN 1995-1-1, Brussel, Belgium.
European Committee for Standardisation (CEN). (2004b). “Eurocode 5—Design of timber structures. Part 1-1: General—Structural fire design.” EN 1995-1-2, Brussel, Belgium.
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.
Frangi, A., and Fontana, M. (2000). “Experimental tests on timber-concrete composite slabs at room temperature and under ISO-fire exposure.” Rep. No. 249, Institute of Structural Engineering, ETH Zurich, Switzerland (in German).
Frangi, A., and Fontana, M. (2003a). “Elasto-plastic model for timber-concrete composite beams with ductile connection.” Struct. Eng. Int. (IABSE, Zurich, Switzerland), 13(1), 47–57.
Frangi, A., and Fontana, M. (2003b). “Charring rates and temperature profiles of wood sections.” Fire Mater., 27, 91–102.
Frangi, A., and Fontana, M. (2003c). “Thermal expansion of wood and timber-concrete composite members under ISO-fire exposure.” Fire Safety Science, 7, 1111–1122.
Gelfi, P., Giuriani, E., and Marini, A. (2002). “Stud shear connection design for composite concrete slab and wood beams.” J. Struct. Eng., 128(12), 1544–1550.
Gerhards, C. C. (1982). “Effect of moisture content and temperature on the mechanical properties of wood: An analysis of immediate effects.” Wood and Fiber, 14, 4–36.
Gutkowski, R. M., Brown, K., Shigidi, A., and Natterer, J. (2004). “Investigation of notched composite wood-concrete connections.” J. Struct. Eng., 130(10), 1553–1561.
ISO. (1999). “Fire-resistance tests—Elements of building construction—Part 1: General requirements.” ISO 834–1, Geneva, Switzerland.
Kenel, A. (2000). “Calculation and dimensioning of timber concrete composite structural elements.” Rep. No. 115/42, Swiss Federal Laboratories for Materials Testing and Research, EMPA, Dübendorf, Switzerland (in German).
König, J. (2005). “Structural fire design according to Eurocode 5—Design rules and their background.” Fire Mater., 29, 147–163.
König, J., and Källsner, B. (2000). “Timber frame assemblies exposed to standard and parametric fires. Part 2: A design model for standard fire exposure.” Rep. No. I 0001001, Trätek—Swedish Institute for Wood Technology Research, Stockholm, Sweden.
König, J., and Källsner, B. (2001). “Cross-section properties of fire exposed rectangular timber members.” Proc., Meeting 34 of the Working Commission W18-Timber Structures, CIB, Int. Council for Research and Innovation, Venice, Italy.
Kreuzinger, H. (1995). “Mechanically jointed beams and columns.” STEP 1: Timber engineering, Paper B11, Centrum Hout, The Netherlands, 1–8.
Kuhlmann, U., and Schänzlin, J. (2008). “A timber-concrete composite slab system for use in tall buildings.” Struct. Eng. Int., 18(2), 174–178.
Möhler, K. (1956). “On the load carrying behavior of beams and columns of compound sections with flexible connections.” Habilitation, Technical Univ. of Karlsruhe, Germany (in German).
Natterer, J., Hamm, J., and Favre, P. (1996). “Composite wood-concrete floors for multi-story buildings.” Proc., Int. Wood Engineering Conf., V.K.A. Gopu, Louisana State Univ., New Orleans, 3431–3435.
Newmark, N. M., Siess, C. P., and Viest, I. M. (1951). “Tests and analysis of composite beams with incomplete interaction.” Proc. Soc. Exp. Stress Anal., 9, 75–92.
Salari, R. M., Spacone, E., Shing, P. B., and Frangopol, D. (1998). “Nonlinear analysis of composite beams with deformable shear connectors.” J. Struct. Eng., 124(10), 1148–1158.
Schaffer, E. L. (1967). “Charring rate of selected woods—Transverse to grain.” Research paper FPL 69, Forest Products Laboratory, Madison.
Schaffer, EL. (1977). “State of structural timber fire endurance.” Wood Fiber, 9(2), 145–170.
Schaffer, E. L., Marx, C. M., Bender, D. A., and Woeste, F. E. (1986). “Strength validation and fire endurance of glued-laminated beams.” Research paper FPL 467, Forest Products Laboratory, Madison.
Stüssi, F. (1943). “Beiträge zur Berechnung und Ausbildung zusammengesetzter Vollwandträger.” Schweizerische Bauzeitung, 121(8), 87–103.
Timmermann, K., and Meierhofer, U. (1993). “Timber concrete composite structural elements: Tests, research and development.” Rep. No. 115/30, Swiss Federal Laboratories for Materials Testing and Research, EMPA, Dübendorf, Switzerland (in German).
Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 136 • Issue 2 • February 2010
Pages: 219 - 228
Copyright
© 2010 ASCE.
History
Received: Dec 26, 2008
Accepted: Aug 31, 2009
Published online: Sep 2, 2009
Published in print: Feb 2010
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.