DOL behaviour of end-notched beams
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Abstract
The long-term loading strength of end-notched beams made of glulam and LVL was tested. The beams were of various sizes, with and without a moisture sealing at the notch. Tests were conducted in open shelter climates, and at constant and cyclic relative humidity. The short-term strength was tested after conditioning in the various climates. Both the short-term and long-term strength of beams without moisture sealing was significantly affected by transient moisture conditions, e.g. the moisture variations due to change of the time of the year. The strength was only slightly affected by the magnitude of the humidity, if this was kept constant. Duration of load strength reduction factors were evaluated for 6 months of loading. Average reductions in ultimate failure strength ranged from 0.68 for small LVL beams without moisture sealing tested during spring and summer to 0.81 for large glulam beams with a moisture sealing at the notch.
Keywords
Moisture Content Crack Initiation Slow Crack Growth Laminate Veneer Lumber Natural ClimateZeitstandfestigkeit keilverzinkter Träger
Zusammenfassung
Die Zeitstandfestigkeit keilverzinkter Träger aus Glulam und LVL wurde geprüft. Die Balken waren unterschiedlich bemessen und mit oder ohne Endversiegelung versehen Die Prüfung erfolgte sowohl in natürlichem, geschützten Klima als auch bei konstanter Feuchte und im Wechselklima. Die Kurzzeitfestigkeit wurde jeweils nach dem Konditionieren geprüft. Alle Ergebnisse an nicht versiegelten Proben waren deutlich beeinflußt durch Feuchteübergänge, z.B. die Feuchtewechsel innerhalb eines Jahres. Die Festigkeit hing nur in geringem Maße vom Wassergehalt ab, wenn dieser konstant gehalten war. Reduktionsfaktoren (k mod) wurden für ömonatige Belastung ermittelt. Die durchschnittlichen Werte für die Bruchlast lagen im Bereich von 0,68 für kleine LVL-Träger ohne Feuchteversiegelung (geprüft im Frühjahr und Sommer) bis zu 0,81 für lange Brettschichtholz-Träger mit Feuchteversiegelung der Keilzinken.
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10 Literature
- Andreasen LV, Hoffmeyer P (1997) Duration of Load Effects on Different Sized Timber Beams. Report Series I No. 17, Department of Structural Engineering and Materials, Technical University of DenmarkGoogle Scholar
- Foliente G, McLain T (1992) Design of Notched Wood Beams. J. of Structural Engineering, 118(9): 2407–2420CrossRefGoogle Scholar
- Gustafsson PJ (1985) Fracture Mechanics Studies of Non-Yielding Materials like Concrete. Thesis TVBM-1007, Division of Building Materials, Lund University, SwedenGoogle Scholar
- Gustafsson PJ (1988) A Study of the Strength of Notched Beams. Paper 21-10-1 in Proc of the CIB-W18A Meeting 21, Parksville, CanadaGoogle Scholar
- Gustafsson PJ, Petersson H, Stefansson F (1996) Fracture Analysis of Wooden Beams with Holes and Notches. In Proc. of the International Wood Engineering Conference, New Orleans, pp. 4.281-4.287Google Scholar
- Guyon G, Valentin G, Morlier P (1987) Durée de vie du bois sous charge constante. In Proc. of the 1st International RILEM Meeting, Vol. III, Versailles, FranceGoogle Scholar
- Henrici D (1984) Beitrag zur spannungsermittlung in ausgeklinkten Biegeträgern aus Holz. Thesis, Fakultät fur Bauingenieur- und Vermessungswesen der Technischen Universität München, GermanyGoogle Scholar
- Jensen SK, Hoffmeyer P (1996) Mechano-sorptive Behaviour of Notched Beams in Bending. In Proc. of the 1996 International Conference on Wood Mechanics, Stuttgart, Germany, pp. 204–213Google Scholar
- Jourdain C, Racois P, Valentin G (1994) Delayed fracture of Spruce notched beams. In Proc. of COST 508 Meeting, Espoo, Finland, pp. 149–156Google Scholar
- Jourdain C (1996) Duration of load effect on notched beams: influence of climate and Application to Laminated Veneer Lumber. Thesis 1639 (in French), Bordeaux 1 University, FranceGoogle Scholar
- Lam C, Foschi O (1988) Arbitrary V-notches in orthotropic plates. J. Engineering Mechanics, 114(4): 638–655CrossRefGoogle Scholar
- Larsen HJ, Riberholt H (1972) Forsög med Uklassificeret Konstruktionstrae. Rapport R31, Afdelningen for Baerende Konstruktioner, Danmarks Tekniske Höjskole (DTU), DenmarkGoogle Scholar
- Leicester RH (1971) Some Aspects of Stress Fields at Sharp Notches in Orthotropic Materials. Paper 57, Division of Forest Products, CSIRO, AustraliaGoogle Scholar
- Möhler K, Mistler, HL (1978) Untersuchungen über den Einfluss von Ausklinkungen im Auflagerbereich von Holzbiegeträgern auf die Tragfestigkeit. Rapport, Lehrstuhl fur Ingenieurholzbau und Baukonstruktionen,Universität Karlsruhe, GermanyGoogle Scholar
- Nordtest (1993) Wood: Fracture Energy in Tension Perpendicular to the Grain. Nordtest Method, NT Build 422, ISSN 0283-7153, Nordtest, FinlandGoogle Scholar
- Riberholt H, Enquist B, Gustafsson PJ, Jensen RB (1992) Timber Beams Notched at the Support. Report TVSM-7071, Division of Structural Mechanics, Lund University, SwedenGoogle Scholar
- Riipola K (1990) Dimensioning of Beams with Cracks, Notches and Holes: An Application of Fracture Mechanics. Paper 23-10-2 in Proc. of the CIB-W18 A Meeting 23, Lisbon, PortugalGoogle Scholar
- Smith I, Springer G (1993) Consideration of Gustafsson’s proposed Eurocode 5 failure criterion for notched timber beams. Canadian J. of Civil Engineering, 20: 1030–1036CrossRefGoogle Scholar
- Toratti T (1988) The Mechanical Properties of Kerto Laminated Veneer Lumber. VTT Report 6 1988, VTT, FinlandGoogle Scholar
- Van der Put TACM (1990) Tension Perpendicular to the Grain at Notches and Joints. Paper 23-10-1 in Proc. of the CIB-W18A Meeting 23, Lisbon, PortugalGoogle Scholar
- Walsh PF (1974) Linear Fracture Mechanics Solutions for Zero and Right Angle Notches. Paper 2 (Second Series), Division of Building Research, CSIRO, AustraliaGoogle Scholar