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25 records – page 1 of 3.

Analysis of Shear Transfer and Gap Opening in Timber–Concrete Composite Members with Notched Connections

https://research.thinkwood.com/en/permalink/catalogue1399
Year of Publication
2017
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
Author
Boccadoro, Lorenzo
Steiger, René
Zweidler, Simon
Frangi, Andrea
Publisher
Springer Netherlands
Year of Publication
2017
Country of Publication
Netherlands
Format
Journal Article
Material
Timber-Concrete Composite
Topic
Connections
Mechanical Properties
Keywords
Notched Connections
Analytical Model
Shear Stress
Failure
Language
English
Research Status
Complete
Series
Materials and Structures
ISSN
1871-6873
Summary
In timber–concrete composite members with notched connections, the notches act as the shear connections between the timber and the concrete part, and have to carry the shear flow necessary for composite action. The shear transfer through the notches generates shear and tensile stresses in both parts of the composite member, which may lead to brittle failure and to an abrupt collapse of the structure. Although simplified design formulas already exist, some structural aspects are still not clear, and a reliable design model is missing. This paper summarizes current design approaches and presents analytical models to understand the shear-carrying mechanism, to estimate the shear stresses acting in the timber and concrete, and to predict failure. The analysis concentrates on three problems: the shearing-off failure of the timber close to the notch, the shear failure of the concrete, and the influence of the shear flow on the gap opening between the timber and concrete. Parts of the model calculations could be compared to experimental observations. The conclusions of this paper contribute to improving current design approaches.
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Bending Tests on Glued Laminated Timber Beams with Well-Known Material Properties

https://research.thinkwood.com/en/permalink/catalogue186
Year of Publication
2013
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Fink, Gerhard
Kohler, Jochen
Frangi, Andrea
Organization
ETH Zurich
Year of Publication
2013
Country of Publication
Switzerland
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Bending Strength
Failure
Load Bearing Capacity
Four Point Bending Test
Density
Model
Bending Stiffness
Language
English
Research Status
Complete
Summary
At the Institute of Structural Engineering at the ETH Zurich numerous of investigations are conducted to analyse the load bearing capacity of glued laminated timber beams. The investigations are part of the research project ’Influence of varying material properties on the load bearing capacity of glued laminated timber (glulam)’. The investigations are taking place on 24 glulam beams with well-known material properties. The glulam beams are fabricated out of 400 timber boards. From those boards the material properties are investigated non-destructively within a former research project. During the glulam fabrication it is particularly focused to keep the information of the timber boards; i.e. after the glulam fabrication the position of each particular timber board within the glulam beam and thus the position of each particular knot is still known. The glulam beams are investigated during a 4-point bending test. On the glulam members the load bearing capacity, the bending stiffness and the density is measured. Furthermore local strains within the glulam beams are investigated using an optical coordinate-measurement device. Following the test the failure is investigated in detail. Hereby the type of failure (knot cluster, finger joint, clear wood) and the amount of failure (number of damaged lamellas) is documented. Afterwards the failed glulam beams are loaded again to analyse the remaining bending strength and the corresponding remaining bending stiffness. The major aim of the experimental analysis is the investigation of the load bearing capacity of glulam beams with well-known local material properties. The gained results can be used for an investigation of the influence of local weak zones, such as knot clusters or finger joints, on the load bearing capacity of glulam. In addition a data basis is produced to develop a new model (or to evaluate existing models) for the estimation of the load bearing capacity of glulam.
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Bending Tests with Glulam Columns under Eccentric Normal Force Stress

https://research.thinkwood.com/en/permalink/catalogue1138
Year of Publication
2015
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Frangi, Andrea
Theiler, Matthias
Organization
ETH Zurich
Year of Publication
2015
Country of Publication
Switzerland
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Load Bearing Capacity
Axial Compression
Buckling Tests
Spruce
Language
German
Research Status
Complete
Summary
The force-displacement behaviour of structural timber members subjected to axial compression or combined axial compression and bending is distinctively non-linear. This behaviour is caused by the non-linear increase of the deformation due to the increasing eccentricity of the axial load as well as by the non-linear material behaviour of timber when subjected to compression. The present report describes experimental investigations on glued laminated timber members subjected to eccentric compression. The aim of these experimental investigations was to create a data base, which can be used to validate theoretical calculation models and to assess the accurateness of the design approaches given in the design codes for timber structures. The specimens for the main bunch of experiments were produced using lamellas made of Norway spruce grown in Switzerland. For this purpose, a total of 336 lamellas were available. In the first step, non-destructive tests on the lamellas were performed. These tests aimed at the collection of data in order to characterise the raw material. In the second step, the lamellas were strength graded. The aim of the grading process was to select two classes of lamellas for the production of the test specimens. The lamellas were selected so that they were suitable to produce glued laminated timber of strength classes GL24h and GL32h. Within the grading process, visual grading criteria as well as machine grading criteria were used. In the third step, the graded lamellas were used to produce glued laminated timber members. Five tests series were produced. Each of the test series consisted of ten specimens. Three series were made of glued laminated timber GL24h and two series were made of glued laminated timber GL32h. The length of the timber members was varied between the different test series. The lengths were L = 1’400 mm, L = 2’300 mm and L = 3’200 mm respectively. During the production, the setup of the test specimens was recorded. Hence, the position and the orientation of every lamella within the test specimen were documented. Additionally, some non-destructive tests were performed using the test specimens. In the last step, the glued laminated timber members were subjected to buckling tests. The test specimens were loaded with an eccentric compression force up to failure. During the tests, different measurements were carried out in order to document the experimental investigations as accurate as possible. Amongst others, the applied loads as well as horizontal and vertical deformations were recorded. For a subsample of 20 test specimens, additional local deformation measurements were performed using an optical measurement device.
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Correct Temperature Measurements in Fire Exposed Wood

https://research.thinkwood.com/en/permalink/catalogue2025
Year of Publication
2018
Topic
Fire
Material
CLT (Cross-Laminated Timber)

Design of Timber Members Subjected to Axial Compression or Combined Axial Compression and Bending Based on 2nd Order Theory

https://research.thinkwood.com/en/permalink/catalogue115
Year of Publication
2015
Topic
Design and Systems
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Author
Frangi, Andrea
Steiger, René
Theiler, Matthias
Organization
International Network on Timber Engineering Research (INTER)
Year of Publication
2015
Country of Publication
Germany
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Topic
Design and Systems
Mechanical Properties
Keywords
Bending
Buckling
Codes
Compression
Deformation
Monte Carlo
Simulation
Structural
Testing
Language
English
Conference
INTER 2015
Research Status
Complete
Notes
August 24-27, 2015, Sibenik, Croatia
Summary
The paper examines the behaviour of structural timber members subjected to axial compression or combined axial compression and bending. Based on experimental and numerical investigations, the accuracy of the existing approach in Eurocode 5 for the design of timber members subjected to axial compression or combined axial compression and bending is assessed and modifications are suggested. By means of extensive experimental investigations, a data base was created for the validation of calculation models and for the assessment of design concepts. In order to assess the behaviour of timber members subjected to axial compression or combined axial compression and bending, strain-based calculation models were developed. The investigations indicate that the existing approach of Eurocode 5 based on 2nd order analysis can lead to an overestimation of the load-bearing capacity. Hence, a modified design approach was developed which agrees with the results of the Monte Carlo simulations very well and thus ensures a safe and economical design of timber members subjected to compression or combined compression and bending.
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Dowelled Timber Connections with Internal Members of Densified Veneer Wood and Fibre-Reinforced Polymer Dowels

https://research.thinkwood.com/en/permalink/catalogue1498
Year of Publication
2016
Topic
Mechanical Properties
Connections
Material
LVL (Laminated Veneer Lumber)
Author
Palma, Pedro
Kobel, Peter
Minor, Alexander
Frangi, Andrea
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Topic
Mechanical Properties
Connections
Keywords
Timber-to-Timber
Densified Veneer Wood
Fibre-Reinforced Polymer
Dowel Type Fastener
Embedment Tests
Bending Test
Shear Test
Full Scale
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 236-243
Summary
The mechanical behaviour of timber-to-timber connections with internal panels of densified veneer wood (DVW) and fibre-reinforced polymer (FRP) dowels was experimentally assessed and a design method, based on EN 1995-1-1, was developed. Embedment tests on DVW plates and bending/shear tests on FRP dowels were performed to characterise these components, followed by full-scale tests of connections assembled with these materials. The results show that these connections exhibit a mechanical behaviour compatible with structural applications, regarding both load-carrying capacity and ductility. The proposed design model is based on EN 1995-1-1’s expressions for connections with dowel-type fasteners and gives good predictions of the experimental load-carrying capacities.
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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
Country of Publication
United States
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
Language
English
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).
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Experiments with Tension and Shear Reinforced Glulam Beams

https://research.thinkwood.com/en/permalink/catalogue2209
Year of Publication
2018
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Blank, Lukas
Frangi, Andrea
Organization
ETH Zurich
Year of Publication
2018
Country of Publication
Switzerland
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Fibre Reinforcement
Bending Resistance
Load Bearing Capacity
Language
English
Research Status
Complete
Series
IBK Bericht
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Field Testing on Innovative Timber Structures

https://research.thinkwood.com/en/permalink/catalogue671
Year of Publication
2014
Topic
Design and Systems
Material
LVL (Laminated Veneer Lumber)
Application
Floors
Frames
Author
Leyder, Claude
Wanninger, Flavio
Frangi, Andrea
Year of Publication
2014
Country of Publication
Canada
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Floors
Frames
Topic
Design and Systems
Keywords
Beech
Post-Tensioned
Office Buildings
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
In timber research, a main objective is the development and promotion of innovative and efficient timber structures. Therefore a pilot building, named ETH House of Natural Resources, has been designed, which uses two innovative structural systems, a post-tensioned timber frame and a composite beech LVL concrete floor. The building will be used as an office building for the Laboratory of Hydraulics, Hydrology and Glaciology from ETH Zürich and will serve as a showcase building of a sustainable and reliable timber construction for students and researchers, among others.
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Fire Tests on Finger-Jointed Timber Boards

https://research.thinkwood.com/en/permalink/catalogue170
Year of Publication
2014
Topic
Fire
Material
Glulam (Glue-Laminated Timber)
Author
Klippel, Michael
Frangi, Andrea
Organization
ETH Zurich
Year of Publication
2014
Country of Publication
Switzerland
Format
Report
Material
Glulam (Glue-Laminated Timber)
Topic
Fire
Keywords
Adhesives
Strength
Finger-joint
Temperature
Fire Resistance
Language
English
Research Status
Complete
Summary
This testing report summarises the experimental investigations on finger-jointed timber speci- mens, glued with different types of adhesives, loaded in tension and exposed to standard ISO-fire. The tests were performed as part of the project entitled “Fire safety of bonded structural timber elements” in the frame of a CTI-project (Commission for Technology and Innovation). The extensive testing programme on finger-jointed timber specimens was performed in cooperation with industry partners at the Swiss Federal Institute of Technology Zurich (ETH Zurich). The main aim of this research project is to clarify if the currently used design model for the fire re- sistance of bonded structural timber elements, such as glued-laminated timber, should consider the behaviour of adhesives at elevated temperatures. In this experimental study, different adhesives available on the market from adhesive man- ufacturer from Europe (such as Casco AG, Dynea AG, Jowat AG, Türmerleim AG, Purbond AG) were tested. Adhesives being used for structural applications as well as adhesives not certified according to current European testing standards for the use in structural applications were tested. The fire performance of 12 different adhesives - of type 1C PUR, MUF, PRF, EPI, PVAc, UF - were tested in a finger-jointed connection for cross-sections with a width of 80, 140 and 200 mm. In total, 49 fire tests were performed under ISO-fire exposure at the Swiss Federal Labora- tories for Materials Testing and Research (EMPA) in Duebendorf/ Switzerland. Two tests were conducted with specimens equipped with thermocouples to determine the temperature distribu- tion along the cross-section width. In the other tests, different parameters and their influence on the fire resistance were varied, such as the adhesive in the finger joint, the width of the specimen, the load level and the type of fire exposure on the testing lamella. The tests were performed in two test series in March and April, 2011 as well as in July and August, 2012. The second test series was extended by five additional tests with higher graded timber in August 2013. The main result from the first test series can be concluded as follows: The adhesives tested (2 x PUR, 1 x MUF) fulfil current approval criteria according to EN 301 (2013c) and EN 15425 (2008) for the use in load-bearing timber components in Europe. The adhesives fulfil at least the A7 test at 70 ° C according to EN 302-1 (2013a). Taking into account the failure pattern, no significant difference was observed between these adhesives. It could be shown that the higher loss of strength for some adhesives tested at elevated temperature does not necessarily lead to the same loss of strength in fire, since defects like knots may be dominant - depending on the strength class (grading). The main result from the second test series can be concluded as follows: No substantial difference was obtained for finger-jointed specimens glued with PRF and other structural ad- hesives. The PUR adhesive fulfilling the ASTM D7247 (2007) standard test at temperatures higher than 200 C did not reach a higher fire resistance than PUR adhesives which do not fulfil this standard. It was found that adhesives, which are used in structural timber members such as glued-laminated timber beams, need sufficient strength at lower temperatures than 200 C. iv This is especially explained by the steep temperature gradient typical for timber members such as glued-laminated timber. In addition to the fire tests, about 120 tensile tests on finger-jointed lamellas were performed at normal temperature. These lamellas were produced with the same types of adhesives as studied in the fire tests. The results of the whole investigation are summarised in this test report
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25 records – page 1 of 3.