No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
EMBEDMENT STRENGTH OF LVL AND CROSS-BANDED LVL MANUFACTURED FROM BLENDING HARDWOOD AND SOFTWOOD SPECIES
Abstract
This paper experimentally evaluates the embedment strength of Laminated Veneer Lumber (LVL) and cross-banded Laminated Veneer Lumber (LVL-C) manufactured from blending spotted gum (Corymbia citriodora subsp. variegata-SPG) veneers with hoop pine (Araucaria cunninghamii-HP) veneers. Nominal 3.0 mm thick veneers were rotary peeled from small diameter (less than 30 cm) native forest sourced SPG logs and commercial plantation grown HP logs. For each species, the veneers were classified into three grades based on their dynamic Modulus of Elasticity (MOE). Six LVL and four LVL-C panels (1.2 m × 0.9 m × 12-ply) were manufactured using four different construction strategies by mixing (i) the number of veneers from each species, (ii) the veneer grades and (iii) the veneer orientations (cross-banding). A total of 240 embedment tests, using three different dowel diameters, were performed using the half-hole test method described in the ASTM D5764-97a. This paper compares (i) the proportional limit strength, 5%-offset embedment strength and maximum embedment strength across the different construction strategies adopted in the study and (ii) discusses the results in terms of load-to-grain angle and dowel diameter. The test results are also compared to the embedment strength prediction equations detailed in the Eurocode 5 to determine their suitability for mixed species LVL products. Overall, the mixed species LVL and LVL-C showed significantly higher embedded strengths than only softwood LVL products. LVL-C samples exhibited a very ductile behaviour for all load-to-grain angles and dowel diameters.
ResearchGate has not been able to resolve any citations for this publication.
In order to be able to realistically and consistently elucidate and subsequently simulate the load–displacement behavior of single-dowel connections, the material behavior of the individual components, namely steel dowels and wood, needs to be investigated. The behavior of slotted-in, single-dowel steel-to-laminated veneer lumber (LVL) connections with dowel diameters of 12 and 20 mm is thoroughly discussed here in relation to steel dowel and LVL properties. In addition to connection tests at different load-to-grain directions of 0°, 45° and 90°, the corresponding embedment behavior of LVL was tested up to dowel displacements of three times the dowel diameter. The material behavior of steel dowels was studied by means of tensile and 3-point bending tests and accompanying finite element simulations. A pronounced nonlinear behavior of the single-dowel connections was observed for all load-to-grain directions. In case of loading perpendicular to the grain, a significant hardening behavior was obvious. Due to the anisotropic material properties of wood, enforcing a loading direction of 45° to the grain resulted in an additional force perpendicular to the load direction which was quantified in a novel biaxial test setup. Thus, a comprehensive and consistent database over different scales of observations of dowel connections could be established, which subsequently was exploited by means of engineering modeling. The comparison of experimental and numerical data illustrates the potential of the engineering modeling approach to overcome drawbacks of current design regulations, which are unable to appropriately predict stiffness properties of dowel connections. Moreover, the quasi-elastic limit of dowel connections was calculated and discussed by means of the model.
This paper deals specifically with the splitting mode of failure, for bolted connections loaded perpendicular to grain in glued laminated timber (glulam). In 2004, a new design equation was developed by Lehoux and Quenneville to predict the ultimate load capacity of these splitting failures. Although the new design equation takes into account the many parameters that affect the ultimate load capacity, the equation was only validated for the Spruce-Pine glulam species. Therefore, the experimental program and research described in this document was undertaken to assess the effect of wood species on connection resistance. It was observed that, as for loading situations governed by tension strength perpendicular to grain, the species has no effect on the splitting resistance of bolted connections.
The current Canadian code provisions for the design of timber bolted connections were essentially developed based on connections showing a ductile behavior and then further modified to account for situations where connections fail in a brittle way. An experimental study was undertaken to evaluate the strength of bolted connections specifically experiencing a brittle mode of failure. Specimens consisting of steel-wood-steel connections with either 19.1 mm or 12.7 mm bolts were tested in tension. Test variables included end distance, bolt spacing, row spacing, number of bolts per row, number of rows, thickness and species of wood member, glulam or sawn lumber members. Connections were tested to the ultimate to observe possible modes of failure as variables were changed. Results show that the current Canadian standard approach to evaluate the resistance of timber bolted connections is not optimal although conservative. Brittle modes of failure such as row shear-out, group tear-out, and splitting were observed. The resistances calculated using the O86.1 design provisions are as little as a third as compared to tested results. Also, the design equations do not allow the designer to take advantage of the increases in strength as a result of increases in row spacing, as observed in tests. Analysis of the results show that the longitudinal shear stress at failure is related to a parameter which is a function of the smaller distance (end distance or bolt spacing) and the specimen thickness. This relation was used to formulate design equations to predict the row shear-out and group tear-out strengths of glulam specimens using the specified strength values listed in O86.1. As well, it was found that Mode I of the European yield model is the only ductile ultimate failure mode and that other equations for bearing failure can be neglected. In this paper, the research program is described, results are presented, and an alternate design approach is proposed to predict the failure mode and the ultimate strength of steel-wood-steel bolted connection groups.Key words: bolt, connection, strength, failure, design, code, ductile, brittle.
National design specification for wood construction
AF&PA
(1997)
National
design
specification
for
wood
construction.Retrieved
from:
https://www.abebooks.com/book-search/title/national-design-specification-wood-construction/.
AF&PA
(2005)
National
Design
Specification
for
Wood
Construction.Retrieved
from:
http://courses.washington.edu/cee454/2005ASD-LRFD_Manual_WEB.pdf.
Evaluating Dowel-Bearing Strength of Wood and Wood-based proucts (ASTM D576497a)
ASTM (2013) Evaluating Dowel-Bearing Strength of Wood and Wood-based proucts (ASTM D576497a).Retrieved from: https://www.astm.org/Standards/D5764.htm.
Bearing properties of Shorea obtusa beneath a laterally loaded bolt
- A Awaludin
- W Smittakorn
- T Hirai
- T Hayashikawa
Awaludin A, Smittakorn W, Hirai T, Hayashikawa T (2007) Bearing properties of Shorea obtusa beneath a laterally
loaded bolt Journal of wood science 53:204-210 doi:10.1007/s10086-006-0842-z
- Bristish Standard
Bristish Standard (2004) Eurocode 5-Design of Timber Structures-Part 1:General Rules and Rules for Buildings
(Bristish
Standard
EN1995-1-1:2004).Retrieved
from:
https://bsol-bsigroupcom.ezproxy.library.uq.edu.au/Bibliographic/BibliographicInfoData/000000000030201375.
Timber Structures-Test methods-Determination of embedment strength and foudation values for dowel type fasteners
- Bristish Standard
Bristish Standard (2007) Timber Structures-Test methods-Determination of embedment strength and foudation
values for dowel type fasteners. (Bristish Standard EN383:2007).Retrieved from: https://bsol-bsigroupcom.ezproxy.library.uq.edu.au/Bibliographic/BibliographicInfoData/000000000030149611.
Basic properties of mechanical wood-joints, 2: Bearing properties of wood under a bolt Research Bulletins of the
- T Hirai
Hirai T (1989) Basic properties of mechanical wood-joints, 2: Bearing properties of wood under a bolt Research
Bulletins of the College Experiment Forests-Hokkaido University (Japan)
Bearing properties of engineered wood products I: effects of dowel diameter and loading direction
- K Hwang
- K Komatsu
Hwang K, Komatsu K (2002) Bearing properties of engineered wood products I: effects of dowel diameter and
loading direction Journal of Wood Science 48:295-301 doi:10.1007/bf00831350
- K Johnsen
Johnsen K (1949) Theory of timber connections Int Assoc Bridge Struct Eng 9:249-262
Experimental Analysis on the Structural Behaviour of Connections with LVL Made of Beech Wood
- P Kobel
- R Steiger
- A Frangi
Kobel P, Steiger R, Frangi A (2014) Experimental Analysis on the Structural Behaviour of Connections with LVL
Made of Beech Wood. In: Materials and Joints in Timber Structures: Recent Developments of
Technology. Springer Netherlands, Dordrecht, pp 211-220. doi:10.1007/978-94-007-7811-5_20
The yield load of bolted and nailed joints Structural Research Laboratory
- H Larsen
Larsen H (1973) The yield load of bolted and nailed joints Structural Research Laboratory, Department of
Structural Engineering and Materials, Technical University of Denmark, International Union of Forestry
Research Organizations (IUFRO), Division 5
Densified Veneer: An Alternative to Steel Plate in Timber
- Ajm Leijten
Leijten AJM (1993) Densified Veneer: An Alternative to Steel Plate in Timber Joints Structural Engineering
International 3:181-183 doi:10.2749/101686693780607859
Optimisation of cross-banded Laminated Veneer Lumber manufactured from Spotted Gum and Southern Pine veneers Bioresources
- H Nguyen
- B P Gilbert
- R Mcgavin
- H Bailleres
Nguyen H, Gilbert BP, McGavin R, Bailleres H (2018) Optimisation of cross-banded Laminated Veneer Lumber
manufactured from Spotted Gum and Southern Pine veneers Bioresources
Design of bolted connections: A comparison of a proposal and various existing standards Proc WCTE
- P Quenneville
Quenneville P (2008) Design of bolted connections: A comparison of a proposal and various existing standards
Proc WCTE
Load-to-grain angle dependence of the embedment behavior of dowel-type fasteners in laminated veneer lumber
- M Schweigler
- T K Bader
- G Hochreiner
- G Unger
- J Eberhardsteiner
Schweigler M, Bader TK, Hochreiner G, Unger G, Eberhardsteiner J (2016) Load-to-grain angle dependence of
the embedment behavior of dowel-type fasteners in laminated veneer lumber Construction and Building
Materials 126:1020-1033 doi:10.1016/j.conbuildmat.2016.09.051
Characteristic properties of nailed and bolted joints under short-term lateral load, part 4-the influence of testing mode and fastener diameter upon embedment test data
- L Whale
- I Smith
- B Hilson
Whale L, Smith I, Hilson B (1989) Characteristic properties of nailed and bolted joints under short-term lateral
load, part 4-the influence of testing mode and fastener diameter upon embedment test data J Inst Wood
Sci 11:156-161
Hilson BO Behaviour of nailed and bolted joints under short-term lateral load-conclusions from some recent research
- L R Whale
- I Smith
Whale LR, Smith I, Hilson BO Behaviour of nailed and bolted joints under short-term lateral load-conclusions
from some recent research. In: Proceedings of CIB W, 1986.
Review of existing and newly developed approaches to obtain timber embedding strength
- T Zhou
- Z Guan
Zhou T, Guan Z (2006) Review of existing and newly developed approaches to obtain timber embedding strength
Progress in Structural Engineering and Materials 8:49-67 doi:10.1002/pse.213