Skip header and navigation

44 records – page 1 of 5.

Experimental Testing of Anchoring Devices for Bottom Rail in Partially Anchored Timber Frame Shear Walls with Two-Sided Sheathing

https://research.thinkwood.com/en/permalink/catalogue400
Year of Publication
2012
Topic
Connections
Material
Light Frame (Lumber+Panels)
Application
Shear Walls
Author
Caprolu, Giuseppe
Organization
Luleå University of Technology
Year of Publication
2012
Format
Report
Material
Light Frame (Lumber+Panels)
Application
Shear Walls
Topic
Connections
Keywords
Failure Modes
Sheathing
Research Status
Complete
Summary
Källsner and Girhammar have presented a new plastic design method for wood-framed shear walls at ultimate limit state. This method allows the designer to calculate the load-carrying capacity of shear walls partially anchored, where the leading stud is not fully anchored against uplift. The anchorage system of shear walls is provided from anchor bolts and hold downs. Anchor bolts provide horizontal shear continuity between the bottom rail and the foundation. Hold downs are directly connected from the vertical end stud to the foundation. When hold downs are not provided, the bottom row of nails transmits the vertical forces in the sheathing to the bottom rail (instead of the vertical stud) where the anchor bolts will further transmit the forces into the foundation. Because of the eccentric load transfer, due to forces acting in the same vertical plane, transverse bending is created in the bottom rail and splitting often occurs. It is important to evaluate this cross-wise bending and to ensure that no brittle failure occur in the bottom rail. The bottom rail is experimentally studied with respect to two primary failure modes, splitting along the bottom of the bottom rail due to cross-wise bending and splitting along the edge side of the bottom rail due forces perpendicular to the grain from the sheathing-to-framing connections. The parameters varied are the size of the washer and the orientation of the pith. The bottom rail was subjected to loading perpendicular to grain through two-sided sheathing. In this report the different set of series are presented. Five sets were conducted depending on the size of the washer and in each set the pith was placed upwards and downwards. The tests showed three different failure modes. In addition to the failure modes that the testing program was aimed at, splitting along the bottom or side of the bottom rail, the final failure was also due to plastic bending and withdrawal of the sheathing-to-framing nails. The results show that the size of the washer has a significant influence on the maximum load and the failure modes. The results show also that the orientation of the pith have a significant influence on the maximum load.
Online Access
Free
Resource Link
Less detail

Investigations on the Serviceability Limit State of Dowel-Type Timber Connections

https://research.thinkwood.com/en/permalink/catalogue911
Year of Publication
2012
Topic
Serviceability
Connections
Author
Dorn, Micheal
Organization
Vienna University of Technology
Year of Publication
2012
Format
Thesis
Topic
Serviceability
Connections
Keywords
dowel-type connection
Steel-to-Timber
Failure Modes
Ductility
Eurocode 5
Strength
Stiffness
contact behavior
finite element method
Research Status
Complete
Summary
The aim of this thesis is to study the load-carrying behaviour of dowel-type steel-to-timber connections in detail. This is achieved by performing experimental tests on single-dowel connections. A large variety of influencing parameters is assessed, which include wood density, connection width, the dowel roughness, and the application of reinforcements in order to prevent brittle behaviour. Separate stages in the loading history are identified, starting from an initial consolidation phase, the region of maximum stiffness during load increase, and the point of maximum connection strength. The results of the experiments are compared to the design practice in Eurocode 5 for strength and stiffness estimation. Strength prediction is conservative except for slender connections, while stiffness prediction complied with experimental results only for connections of intermediate width.
Online Access
Free
Resource Link
Less detail

Experimental Analysis of the Structural Behavior of Timber-Concrete Composite Slabs Made of Beech-Laminated Veneer Lumber

https://research.thinkwood.com/en/permalink/catalogue611
Year of Publication
2013
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
LVL (Laminated Veneer Lumber)
Application
Floors
Author
Boccadoro, Lorenzo
Frangi, Andrea
Publisher
American Society of Civil Engineers
Year of Publication
2013
Format
Journal Article
Material
Timber-Concrete Composite
LVL (Laminated Veneer Lumber)
Application
Floors
Topic
Connections
Mechanical Properties
Keywords
Beech
Spruce
Load Carrying Capacity
Structural Behavior
Failure Modes
Notch Connections
Research Status
Complete
Series
Journal of Performance of Constructed Facilities
Summary
The wood engineering community has dedicated a significant amount of effort over the last decades to establish a reliable predictive model for the load-carrying capacity of timber connections under wood failure mechanisms. Test results from various sources (Foschi and Longworth 1975; Johnsson 2003; Quenneville and Mohammad 2000; Stahl et al. 2004; Zarnani and Quenneville 2012a) demonstrate that for multi-fastener connections, failure of wood can be the dominant mode. In existing wood strength prediction models for parallel to grain failure in timber connections using dowel-type fasteners, different methods consider the minimum, maximum or the summation of the tensile and shear capacities of the failed wood block planes. This results in disagreements between the experimental values and the predictions. It is postulated that these methods are not appropriate since the stiffness in the wood blocks adjacent to the tensile and shear planes differs and this leads to uneven load distribution amongst the resisting planes (Johnsson 2004; Zarnani and Quenneville 2012a). The present study focuses on the nailed connections. A closed-form analytical method to determine the load-carrying capacity of wood under parallel-to-grain loading in small dowel-type connections in timber products is thus proposed. The proposed stiffness-based model has already been verified in brittle and mixed failure modes of timber rivet connections (Zarnani and Quenneville 2013b).
Online Access
Free
Resource Link
Less detail

Design of Multiple Bolted Connections for Laminated Veneer Lumber

https://research.thinkwood.com/en/permalink/catalogue252
Year of Publication
2014
Topic
Connections
Design and Systems
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Yeh, Borjen
Rammer, Douglas
Linville, Jeff
Year of Publication
2014
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Connections
Design and Systems
Keywords
National Design Specifications for Wood Construction (NDSR)
Failure Modes
Bolted Connection
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
The design of multiple bolted connections in accordance with Appendix E of the National Design Specification for Wood Construction (NDS) has incorporated provisions for evaluating localized member failure modes of row and group tear-out when the connections are closely spaced. Originally based on structural glued laminated timber (glulam) members made with all L1 Douglas fir-Larch laminating lumber, the NDS provisions were confirmed by additional analysis, which indicates the applicability of the provisions to glulam with reduced design shear values. Due to the similarity to glulam in the grain orientation and layup strategy, laminated veneer lumber (LVL) is subject to similar failure modes. As a result, a study was initiated by APA – The Engineered Wood Association and the LVL industry, in collaboration with the Forest Products Laboratory (FPL) of the U.S. Department of Agriculture (USDA) to evaluate if a reduced design shear stress is necessary for LVL under similar multiple bolted connection configurations. This paper describes the test results obtained from the study, which indicate that an adequate load factor exists for LVL multiple bolted connections without a reduction in the LVL design shear stress when designed in accordance with Appendix E of the NDS.
Online Access
Free
Resource Link
Less detail

Racking Resistance and Ductility of CLT Shear Walls Under Horizontal and Vertical Loads

https://research.thinkwood.com/en/permalink/catalogue457
Year of Publication
2014
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Yasumura, Motoi
Ito, Yoshimasa
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Mechanical Properties
Connections
Keywords
Yield Load
Ultimate Load
Failure Modes
Joints
Hold-Down
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
The determination procedure of the failure mechanism of CLT shear walls due to the failure of joints was presented in the 45th CIB-W18 meeting in Vaxjo1. It showed that the reliability based analysis based on the ultimate capacity of fasteners predicted quite well the failure process of shear walls when a rigid loading beam was applied. However, the failure process due to the failure of hold-down connectors was not very clear when the flexible loading beam was used. Therefore additional lateral loading tests were conducted by using flexible loading beam as shown in Fig.1 with different procedures to determine the failure mode. This new procedure based on the yield strength of shear plates and the ultimate capacity of hold-down connectors showed better determination of the failure mechanism of CLT shear walls without conspicuous slips between CLT panels. This paper shows the racking test results of CLT shear walls with different failure modes. The failure modes of shear walls were designed by using reliability analysis considering the failure of the hold down connections at the bottom end of shear wall and that of the joints connecting two CLT panels at the centre of the wall. It was shown that the design of joints with the yield capacity Py for the central joints SP and the ultimate capacity Pu for the hold down connection HD (Mode III) determined well the precedence of HD failure without slips in SP and showed high capacity, while Modes I and II failure showed higher ductility than Mode III failure.
Online Access
Free
Resource Link
Less detail

Failure Modes in CLT Connections

https://research.thinkwood.com/en/permalink/catalogue495
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Mohammad, Mohammad
Quenneville, Pierre
Salenikovich, Alexander
Zarnani, Pouyan
Munoz, Williams
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Failure Modes
Brittle Behaviour
Canada
New Zealand
Dowels
Bolts
Rivets
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Information on ductile and brittle failure modes is critical for proper design of timber connections in Crosslaminated Timber (CLT). While considerable research has been conducted in Europe and Canada on the ductile performance of connections in CLT, little is known about the brittle behaviour. This paper presents new information from testing programs and analysis performed in Canada and in New Zealand on the brittle performance of dowel-type fasteners in CLT. The testing programs have been designed to trigger brittle failure modes based on minimum end distances and fasteners spacings specified in the Canadian timber design standard. Timber rivets and bolts/dowels are covered under this study. At the time of writing of this abstract, the testing program is advancing and results will be available at the time of paper submission.
Online Access
Free
Resource Link
Less detail

Bond Behavior of Glued-In Timber Joint with Deformed Bar Epoxied in Glulam

https://research.thinkwood.com/en/permalink/catalogue537
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Ling, Zhibin
Liu, Weiqing
Yang, Huifeng
Lu, Weidong
Year of Publication
2014
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Glued-in Rods
Bond behavior
Withdrawal Strength
Pull-Pull tests
Failure Modes
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
This paper describes the test program of glued-in deformed bar timber joint conducted in pull-pull configuration, which aims to investigate the bond behavior of glued-in deformed bar systems in glulam. The varying parameter are bar slenderness ratio and glue-line thickness. In order to obtain the bond stress distribution along the anchorage length, special deformed bar with strain gauges attached internally were designed. Test results show that both the bar slenderness ratio and glue-line thickness have obvious influence on withdrawal strength and bond behavior of glued-in deformed bar joint. Failure modes of specimens are also analyzed in this paper. Ductile failure modes of glued-in rod timber joint could be realized with reasonable design.
Online Access
Free
Resource Link
Less detail

Group Tear-Out in Small-Dowel-Type Timber Connections: Brittle and Mixed Failure Modes of Multinail Joints

https://research.thinkwood.com/en/permalink/catalogue579
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Zarnani, Pouyan
Quenneville, Pierre
Publisher
American Society of Civil Engineers
Year of Publication
2014
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Connections
Mechanical Properties
Keywords
dowel-type connections
Load Carrying Capacity
Brittle Failure
Failure Modes
Research Status
Complete
Series
Journal of Structural Engineering
Summary
In existing wood strength prediction models for parallel to grain failure in timber connections using dowel-type fasteners, different methods consider the minimum, maximum, or summation of the tensile and shear capacities of the failed wood block planes. It is postulated that these methods are not appropriate since the stiffness of the adjacent wood loading the tensile and shear planes differs, and this leads to uneven load distribution among the resisting planes. A closed-form analytical method to determine the load-carrying capacity of wood under parallel-to-grain loading in small-dowel-type connections in timber products is thus proposed. For the wood strength, the stiffness of the adjacent loading volumes and strength of the failure planes subjected to nonuniform shear and tension stresses are considered. The effective wood thickness for the brittle failure mode is derived and related to the elastic deformation of the fastener. A mixed failure mode is also defined (a mixture of brittle and ductile) and depends on the governing ductile failure mode of the fastener. To help the designer, an algorithm is presented that allows the designer to calculate the resistances associated with predictions of the different possible brittle, ductile, and mixed failure modes. The proposed stiffness-based model has already been verified in brittle and mixed failure modes of timber rivet connections. In the research reported in this paper, an extended application is proposed for other small-dowel-type fasteners such as nails and screws. Results of nailed joint tests on laminated veneer lumber (LVL) and the test data available from the literature on glulam confirm the validity of this new method, and show that it can be used as a design provision for wood load-carrying capacity prediction of small-dowel-type timber connections.
Online Access
Free
Resource Link
Less detail

Feasibility of Using Poplar as Cross Layer to Fabricated Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue620
Year of Publication
2014
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Wang, Zhiqiang
Fu, Hongmei
Chui, Ying-hei
Gong, Meng
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Bonding Strength
Shear Strength
Modulus of Elasticity
Failure Modes
Poplar
Douglas-Fir
Pine
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Use of poplar (Populus euramericana cv. I-214) as cross layer to manufacture cross-laminated timber (CLT) was examined in this study. For comparison purpose, Douglas fir (Pseudotsuga menziesii) and Monterey pine (Pinus radiata D.Don) were used as well to produce five layups of CLT panels. The mechanical properties tested in this study included the bending strength in the major direction, modulus of elasticity in the major direction, shear strength parallel to the major direction and shear strength perpendicular to the major direction. It was found that the mechanical properties of CLT panels containing poplar were similar to those made of non-poplar wood. The major failure modes found were joint failure, shear failure and delamination. It could be feasible to use poplar as a cross layer to fabricate CLT without decreasing its strength properties.
Online Access
Free
Resource Link
Less detail

Cross-Laminated Timber Failure Modes for Fire Conditions

https://research.thinkwood.com/en/permalink/catalogue188
Year of Publication
2015
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Author
Emberley, Richard
Torero, José
Year of Publication
2015
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Keywords
Adhesives
Charring Rate
Delamination
Codes
Failure Modes
Conference
International Conference on Performance-based and Life-cycle Structural Engineering
Research Status
Complete
Notes
December 9-11, 2015, Brisbane, Australia
Summary
Tall timber building designs have utilized cross-laminated timber (CLT) significantly over the past decade due the sustainable nature of timber and the many advantages of using an engineered mass timber product. Several design methods have been established to account for the composite action between the orthogonally adhered timber plies. These methods assume perfect bonding of the adjacent plies by the adhesive. CLT designs methods for timber in fire have also been formulated. These methods rely on the relatively constant charring rate of timber to calculate a sacrificial layer to be added onto the cross-sectional area. While these methods focus on the timber failure mode of reduced cross section by charring, the failure mode of ply delamination is often overlooked and understudied. Due to the reduction of shear and normal strength in the adhesive, the perfect bond assumption can be questioned and a deeper look into the mechanics of CLT composite action and interfacial stress needs be conducted. This paper seeks to highlight the various design methods for CLT design and identify the failure mode of delamination not present in the current design codes.
Online Access
Free
Resource Link
Less detail

44 records – page 1 of 5.