Abstract
Finger joints are commonly used to produce engineered wood products like glued laminated timber beams. Although comprehensive research has been conducted on the structural behaviour of finger joints at ambient temperature, there is very little information about the structural behaviour at elevated temperature. A comprehensive research project on the fire resistance of bonded timber elements is currently ongoing at the ETH Zurich. The aim of the research project is the development of simplified design models for the fire resistance of bonded structural timber elements taking into account the behaviour of the adhesive used at elevated temperature. The paper presents the results of a first series of tensile and bending tests on specimens with finger joints pre-heated in an oven. The tests were carried out with different adhesives that fulfil current approval criteria for the use in load-bearing timber components. The results showed substantial differences in temperature dependant strength reduction and failure between the different adhesives tested. Thus, the structural behaviour of finger joints at elevated temperature is strongly influenced by the behaviour of the adhesive used for bonding and may govern the fire design of engineered wood products like glued laminated timber beams.
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References
ASTM 5572 (1995) Adhesives used for finger joints in nonstructural lumber products
ASTM D7247—07ae1 (2007) Standard test method for evaluating the shear strength of adhesive bonds in laminated wood products at elevated temperatures
Ayarkwa J, Hirashima Y, Sasaki Y, Ando K (2000) Effect of glue type on flexural and tensile properties of finger-jointed tropical African hardwoods. For Prod J 50(10):59–68
Clauß S, Joscak M, Niemz P (2011) Thermal stability of glued wood joints measured by shear tests. Eur J Wood Prod 69(1):101–111
Dorn H, Egner K (1961) Brandversuche mit geleimten Holzbauteilen. Holz-Zentralblatt Stuttgart 87(28):435–438
Dorn H, Egner K (1967) Brandversuche an Brettschichtverleimten Holzträger unter Biegebeanspruchung. Holz Roh- Werkst 25(8):308–320
Dreyer R (1969) Brandverhalten von Holzträgern unter Biege- und Feuerbeanspruchung. Bauen Mit Holz 71(5):225–227
EN 15425 (2008) Adhesives—one component polyurethane for load bearing timber structures—classification and performance requirements
EN 1995-1-2 (2004) Eurocode 5: design of timber structures, part 1–2: general—structural fire design
EN 301 (2006) Adhesives—phenolic and aminoplastic—for load-bearing timber structures—classification and performance requirements
Frangi A (2001) Brandverhalten von Holz-Beton-Verbunddecken, PhD Thesis No. 14328, ETH Zurich
Frangi A, Fontana M, Mischler A (2004) Shear behaviour of bond lines in glued laminated timber beams at high temperatures. Wood Sci Technol 38:119–126
Frangi A, Fontana M, Hugi E, Jöbstl R (2009) Experimental analysis of cross-laminated timber panels in fire. Fire Saf J 44:1078–1087
Gerhards CC (1982) Effect of moisture and temperature on the mechanical properties of wood: an analysis of immediate effects. Wood Fiber 14(1):4–36
Glos P, Henrici D (1990) Festigkeit von Bauholz bei hohen Temperaturen, Abschlussbericht 87505. Institut für Holzforschung der Universität München
Gonzàlez G, Moya R, Monge F, Còrdoba R, Coto JC (2004) Evaluating the strength of finger-jointed lumber of Gmelina Arborea in Costa Rica. New For 28:319–323
Heimeshoff B, Glos P (1980) Zugfestigkeit und Biege-E-Modul von Fichten-Brettlamellen. Holz Roh Werkst 38:51–59
ISO 3130 (1975) Wood—determination of moisture content for physical and mechanical tests
Källander B, Lind P (2001) Strength properties of wood adhesives after exposure to fire, Nordtest Project no 1482-00, SP Report 2001:35, SP Swedish National Testing and Research Institute
König J (2005) Structural fire design according to Eurocode 5—Design rules and their background. Fire Mater 29:147–163
König J, Walleij L (2000) Timber frame assemblies exposed to standard and parametric fires, part 2: a design model for standard fire exposure, Trätek—Swedish Institute for Wood Technology Research, Report I 0001001, Stockholm
König J, Norén J, Sterley M (2008) Effect of adhesives on finger joint performance in fire, paper CIB-W18/41-16-1. In: Proceedings of 41th CIB-W18 Meeting, St. Andrews, Canada
Larsen HJ (1979) Bøjnings- og trackstyrke af fingerskarringer, Rapport Nr. 790, Institute of Building Technology and Structural Engineering, Aalborg, Denmark
Larsen HJ (1980) Strength of finger joints, paper CIB-W18/13-7-9. In: Proceedings of 13th CIB-W18 Meeting, Otaniemi, Finland
Mischler A, Frangi A (2001) Pull-out tests on glued-in rods at high temperatures, paper CIB-W18/34-16-3. In: Proceedings of 34th CIB-W18 Meeting, Venice, Italy
Nielsen PC, Olesen FB (1982) Tensile strength of finger joints at elevated temperatures. Institute of Building Technology and Structural Engineering, Report No. 8205, Aalborg University, Denmark
Nyman HJ (1980) The influence of temperature and moisture on the strength of wood and glue joints. Symposium on fire resistance of wood structures, VTT Symposium 9, VTT Technical Research Centre of Finland
Özçifiçi A, Yapici F (2008) Structural performance of the finger-jointed strength of some wood species with different joint configurations. Constr Build Mater 22:1543–1550
Papadopoulos A (2008) The effect of acetylation on bending strength of finger jointed beech wood (Fagus sylvatica L.). Holz Roh Werkst 66:309–310
Serrano E (2000) Adhesive joints in timber engineering: Modelling and testing of fracture properties. Ph.D. thesis, Report TVSM-1012, Division of Structural Mechanics, Lund University, Sweden
Vassiliou V, Barboutis I, Karasterogiou S (2007) Effect of PVAc bonding on finger-joint strength of steamed and unsteamed beech wood (Fagus sylvatica). J Appl Polym Sci 103:1664–1669
Wescott J, Birkeland M, Traska A, Frihart C, Dally B (2007) New method for rapid testing of bond strength for wood adhesives. In: Proceeding of 30th annual meeting. The Adhesion Society Inc., Tampa Bay, Florida, USA
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Frangi, A., Bertocchi, M., Clauß, S. et al. Mechanical behaviour of finger joints at elevated temperatures. Wood Sci Technol 46, 793–812 (2012). https://doi.org/10.1007/s00226-011-0444-9
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DOI: https://doi.org/10.1007/s00226-011-0444-9