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Bond Behavior between Glulam and GFRP’s by Pullout Tests

https://research.thinkwood.com/en/permalink/catalogue560
Year of Publication
2011
Topic
Connections
Design and Systems
Material
Glulam (Glue-Laminated Timber)
Author
Sena-Cruz, José
Branco, Jorge
Jorge, Marco
Barros, Joaquim
Silva, Catarina
Cunha, Vitor
Publisher
ScienceDirect
Year of Publication
2011
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Design and Systems
Keywords
GFRP
Bond behavior
Pull-Out Tests
Stress-Slip
Research Status
Complete
Series
Composites Part B: Engineering
Summary
To evaluate the bond behavior between glulam and GFRP rods, applied according to the nearsurface mounted strengthening technique, an experimental program composed of beam and direct pullout tests was carried. In this experimental program three main variables were analyzed: the GFRP type, the GFRP location into the groove, and the bond length. From the monitoring system it was registered the loaded and free end slips, and the pullout force. Based on these experimental results, and applying an analytical-numerical strategy, the local bond stress-slip relationship was calculated. In this work the tests are described, the obtained results are presented and discussed, and the applicability of the inverse analysis to obtain the local bond law is demonstrated.
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Bond Between Glulam and NSM CFRP Laminates

https://research.thinkwood.com/en/permalink/catalogue331
Year of Publication
2013
Topic
Design and Systems
Material
Glulam (Glue-Laminated Timber)
Author
Sena-Cruz, José
Jorge, Marco
Branco, Jorge
Cunha, Vitor
Publisher
ScienceDirect
Year of Publication
2013
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Design and Systems
Keywords
Carbon Fiber Reinforced Polymer
Pull-Out Tests
Bond behavior
Stress-Slip
Research Status
Complete
Series
Construction and Building Materials
Summary
With the aim of evaluating the bond behaviour between glulam and carbon fibre reinforced polymer laminates strips, an experimental program using pull-out tests was carried, when the near-surface strengthening technique is applied. Two main variables were studied: the bond length and the type of pull-out test configuration. The instrumentation included the loaded and free-end slips, as well as the pullout force. Based on the obtained experimental results, and applying an analytical-numerical strategy, the local bond stress-slip relationship was determined. In this work the tests are described, the obtained results are presented and analysed, and the applicability of an inverse analysis to obtain the local bond law is demonstrated.
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Combination of laser scanner and drilling resistance tests to measure geometry change for structural assessment of timber beams exposed to fire

https://research.thinkwood.com/en/permalink/catalogue3057
Year of Publication
2021
Topic
Fire
Application
Beams
Author
Cabaleiro, Manuel
Suñer, Carlos
Sousa, Hélder S.
Branco, Jorge M.
Organization
University of Vigo
University of Minho
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Application
Beams
Topic
Fire
Keywords
Drilling Resistance Test
Structural Assessment
Laser Scanning
Cloud Point
Research Status
Complete
Series
Journal of Building Engineering
Summary
A structure may be totally destroyed due to a fire, but often it is only partially damaged and parts of it may still be salvaged and reused. For buildings with significant historic and cultural value, it is of utmost importance that these elements, which were only partially damaged, can still be recovered as to preserve the authenticity of the structure. In the case of timber elements after a fire, it is common to find damage on the cross-section exterior part, whereas the inner part presents still a non-damaged section. Therefore, the element is often found with an exterior irregular shape, either due to its original shape prior decay or due to the exposure to fire, that does not coincide with the inner residual cross-section. Moreover, it is essential to perform a preliminary safety analysis to verify which elements can be preserved and to what extent interventions could be needed. The objective of this work is to apply a methodology that allows to calculate the residual cross-section of partially burnt timber elements structures as to calculate the resistant and apparent sections for geometry assessment and to implement that information in three-dimensional structural models. For this purpose, this work proposes a methodology based on a combination of drilling resistance tests together with laser scanner measurements. The methodology was first tested and calibrated within a controlled laboratory environment and then validated onsite using elements from a building exposed to a past fire. The Casa de Sarmento (Sarmento's House) in Guimarães (Portugal) was used as case study, where various structural damages due to a past fire were found.
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Design of Connections in Timber Structures

https://research.thinkwood.com/en/permalink/catalogue1937
Year of Publication
2018
Topic
Connections
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Bader, Thomas
Blaß, Hans Joachim
Bocquet, Jean-François
Branco, Jorge
Brandner, Reinhard
Manuel Cabrero, José
de Proft, Kurt
Descamps, Thierry
Dietsch, Philipp
Franke, Bettina
Franke, Steffen
Görlacher, Rainer
Jockwer, Robert
Jorissen, André
Kleiber, Marion
Lemaître, Romain
Munch-Andersen, Jørgen
Pazlar, Tomaž
Ranasinghe, Keerthi
Ringhofer, Andreas
Sandhaas, Carmen
Schweigler, Michael
Stepinac, Mislav
Tuhkanen, Eero
Verbist, Maxime
Yurrita, Miguel
Editor
Sandhaas, Carmen
Munch-Andersen, Jørgen
Dietsch, Philipp
Publisher
COST (European Cooperation in Science and Technology)
Year of Publication
2018
Format
Book/Guide
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Design and Systems
Keywords
Eurocode 5
Fasteners
Screws
Dowel Type Fastener
Glued-In Rods
Numerical Modeling
Europe
Load Distribution
Research Status
Complete
Summary
This state-of-the-art report has been prepared within COST Action FP1402 Basis of structural timber design from research to standards, Working Group 3 Connections. The Action was established to create an expert network that is able to develop and establish the specific information needed for standardization committee decisions. Its main objective is to overcome the gap between broadly available scientific results and the specific information needed by standardization committees. This necessitates an expert network that links practice with research, i.e. technological developments with scientific background. COST presents the ideal basis to foster this type of joint effort. Chapter 8 Connections presents an integral part of Eurocode 5 and is in need of revision. This state-of-the-art report shall provide code writers with background information necessary for the development of the so-called Second Generation of the Eurocodes, now aimed to be produced in 2022.
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Finite Element Modelling of the Cyclic Behaviour of CLT Connectors and Walls

https://research.thinkwood.com/en/permalink/catalogue1653
Year of Publication
2016
Topic
Mechanical Properties
Seismic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Aranha, Chrysl
Branco, Jorge
Lourenço, Paulo
Flatscher, Georg
Schickhofer, Gerhard
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Mechanical Properties
Seismic
Connections
Keywords
Shear Tests
Axial Tests
Cyclic Loads
Force-Displacement Curves
Numerical Model
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3533-3540
Summary
The characterization of the behaviour of connectors used in Cross-laminated Timber (CLT) structures is an important aspect that needs to be considered in their seismic design. In this paper, the data from shear and axial tests conducted on connectors have been used to define their force-displacement curves under cyclic loads using the SAWS model in OpenSees. The component curves were then incorporated into the corresponding wall models and the results were compared with their experimental counterparts, in order to determine the validity of the finite element model. Thereby, the non-linear behaviour was restricted to the connectors while the walls themselves were composed of linear orthotropic shell elements. The models were found to provide a good estimate of the initial stiffness and maximum load capacity of the wall specimens. The effects of vertical loading and the presence of openings were determined based on analyses run on the calibrated model.
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Fragility Analysis of a Mass-Timber Frame Structure with Ring-Doweled Moment-Resisting Connections

https://research.thinkwood.com/en/permalink/catalogue2065
Year of Publication
2018
Topic
Connections
Mechanical Properties
Seismic
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Rodrigues, Leonardo
Neves, Luís
Barbosa, André
Branco, Jorge
Organization
University of Minho
University of Nottingham
Oregon State University
Year of Publication
2018
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Connections
Mechanical Properties
Seismic
Keywords
Eurocode 5
Eurocode 8
Non-Linear Model
Failure Modes
Fragility Curves
Nonlinear Static Analysis
Multi-Record Incremental Dynamic Analysis
Ring-Doweled Connections
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
The nonlinear behaviour of connections between structural elements is critical to the performance of mass-timber structures under seismic loads. However, limited work has been developed in nonlinear modelling and fragility assessment of mass-timber structures. To improve the accuracy of this approach, in particular when considering structures with ring-doweled moment-resisting connections, a nonlinear modelling approach and fragility assessment are proposed and a prototype example of a three-story building is analysed herein as a case study. For the case study, connections and members were designed following the prescriptions in Eurocode 5 and Eurocode 8, considering a high ductility structure. The mechanical properties of the structure are modelled as random variables to evaluate the impact of uncertainty on the prediction of the structural performance, in particular, on the probability of occurrence of ductile and brittle failure modes. The structure is studied under both nonlinear static analysis and multi-record incremental dynamic analysis. From these, fragility curves for different damage levels are computed and a q-factor is proposed. Results indicate that the requirements of Eurocode 5 and Eurocode 8 are sufficient to guarantee adequate performance for this type of structure, albeit these may be overconservative. Moreover, it is shown that uncertainties in material properties have a significant impact on the collapse capacity of these structures.
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Influence of Moisture Content and Gaps on the Withdrawal Resistance of Self Tapping Screws in CLT

https://research.thinkwood.com/en/permalink/catalogue299
Year of Publication
2014
Topic
Connections
Mechanical Properties
Moisture
Material
CLT (Cross-Laminated Timber)
Author
Silva, Catarina
Ringhofer, Andreas
Branco, Jorge
Lourenço, Paulo
Schickhofer, Gerhard
Organization
National Congress of Experimental Mechanics
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Moisture
Keywords
Self-Tapping Screws
Withdrawal
Gaps
Moisture Content
Conference
9th National Congress of Experimental Mechanics
Research Status
Complete
Notes
October 15-17, 2014, Aveiro, Portugal
Summary
Self-tapping screws (STS) have been proclaimed as the easiest solution for structural timber connections, in special for cross laminated timber (CLT) constructions. In order to understand deeply the composite model “CLT-STS”, an experimental campaign which comprised 270 withdrawal tests was carried out. Maximum withdrawal load capacity of self-tapping screws inserted in plane side of a three layered CLT panel was evaluated considering three main parameters: moisture levels of CLT (i), number of gaps (ii) and the width of gaps (iii). Regarding (i), connections were tested with CLT at 8%, 12% and 18% of moisture content. Concerning (ii) and (iii), different test configurations with 1, 2 and 3 gaps, with 0 or 4mm, were tested. The influences of moisture content and number of gaps were modeled. Further a correlation between test results and a prediction model developed by Uibel and Blaß (2007) has been proposed.
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The Influences of Moisture Content Variation, Number and Width of Gaps on the Withdrawal Resistance of Self Tapping Screws inserted in Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1359
Year of Publication
2016
Topic
Connections
Moisture
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Silva, Catarina
Branco, Jorge
Ringhofer, Andreas
Lourenço, Paulo
Schickhofer, Gerhard
Publisher
ScienceDirect
Year of Publication
2016
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Moisture
Mechanical Properties
Keywords
Withdrawal Tests
Withdrawal Resistance
Self-Tapping Screws
Moisture Content
Gaps
Research Status
Complete
Series
Construction and Building Materials
Summary
A large experimental campaign comprised of 470 withdrawal tests was carried out, aiming to quantify the withdrawal resistance of self-tapping screws (STS) inserted in the side face of cross laminated timber (CLT) elements. In order to deeply understand the “CLT-STS” composite model, the experimental tests considered two main parameters: (i) simple and cyclic changes on moisture content (MC) and (ii) number and width of gaps. Regarding (i), three individual groups of test specimens were stabilized with 8%, 12% and 18% of moisture content and one group was submitted to a six month RH cycle (between 30% and 90% RH). Concerning (ii), different test configurations with 0 (REF), 1, 2 and 3 gaps, and widths equal to 0mm (GAP0) or 4mm (GAP4), were tested. The influences of MC and number of gaps were modeled by means of least square method. Moreover, a revision of a prediction model developed by Uibel and Blaß (2007) was proposed. The main findings of the experimental campaign were: the decrease of withdrawal resistance for specimens tested with MC=18% in most configurations; the unexpected increase of withdrawal resistance as the number of gaps with 0mm increased; and, the surprising increase of withdrawal resistance for REF specimens submitted to the RH cycle.
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In-Plane Stiffness of Timber Floors Strengthened with CLT

https://research.thinkwood.com/en/permalink/catalogue516
Year of Publication
2015
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Branco, Jorge
Kekeliak, Milos
Lourenço, Paulo
Publisher
Springer Berlin Heidelberg
Year of Publication
2015
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Mechanical Properties
Connections
Keywords
Full Scale
Numerical model
Push-Out Tests
Stiffness
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
Five full-scale timber floors were tested in order to analyse the in-plane behaviour of these structural systems. The main objective was an assessment of the effectiveness of in-plane strengthening using cross-laminated timber (CLT). To that end, one unstrengthened specimen (original), one specimen strengthened with a second layer of floorboards, two specimens strengthened with three CLT panels, and one specimen strengthened with two CLT panels, were tested. A numerical analysis was then performed in order to analyse the composite behaviour of the timber floors in more detail. Due to its importance as regards composite behaviour, the first phase of the experimental programme was composed of push out tests on specimens representing the shear connection between the timber beams and the CLT pan CLT panels. This paper describes els. This paper describes the tests performed and the numerical modelling applied the tests performed and the numerical modelling applied to evaluate the composite behaviour of the strengthened timber floors. The use of CLT panels is revealed to be an effective way to increase the in-plane stiffness of timber floors, through which the behaviour of the composite structure can be significantly changed, depending on the connection applied, or modified as required.
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A Project Contribution to the Development of Sustainable Multi-Storey Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue1162
Year of Publication
2013
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Silva, Catarina
Branco, Jorge
Lourenço, Paulo
Year of Publication
2013
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Urban Timber System
Conference
Portugal SB13
Research Status
Complete
Notes
October 30-November 1 2013, Guimarães, Portugal
Summary
Wood is a natural material, renewable, easily recyclable, and able to store carbon-dioxide, which makes tall timber buildings a solution with potential to answer the main sustainability targets. Cross laminated timber (CLT) has been pointed out as the best wood-based material to make this ambition a real thing. In order to understand why, this paper introduces the material and describe some demonstration buildings recently built. Based on diagnosed weaknesses of CLT buildings, it is presented an initial propose for a new CLT/glulam hybrid construction system, called Urban Timber (UT) system, which aims be able to support taller timber buildings. The main motivation was the development of a wood-based structural solution that provides more spatial flexibility and wider versatility for visual architectural expressions. The system is described and illustrated, considering concerns related with structural behavior, architectural value, structural connections and wood shrinkage.
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14 records – page 1 of 2.