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30 records – page 1 of 3.

Quantifying robustness in tall timber buildings: A case study

https://research.thinkwood.com/en/permalink/catalogue3106
Year of Publication
2022
Author
Voulpiotis, Konstantinos
Schär, Styfen
Frangi, Andrea
Organization
Swiss Federal Institute of Technology
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Keywords
Disproportionate Collapse
Tall Timber
System Effects
Risk
Reliability
Classification
Sensitivity Study
Research Status
Complete
Series
Engineering Structures
Summary
Robustness research has become popular, however very little is known on its explicit quantification. This paper summarises a quantification method previously published by the main author and proceeds in demonstrating its step-by-step application with a case study tall timber building. A hypothetical 15-storey post-and-beam timber building with a central core is designed for normal loads, and four improved options are designed to account for abnormal loads in order to increase the building’s robustness. A detailed, nonlinear, dynamic Finite Element model is set up in Abaqus® to model three ground floor column removal scenarios, and a Random Forest classifier is set up to propagate uncertainties, to efficiently estimate the probability of certain collapse classes occurring, and to calculate the importance of each input parameter. The results show how design improvements at the whole building scale (e.g., strong floors) have a higher impact on robustness performance than just improving the strength and ductility of some selected connections, although these results are exclusive to the building studied. The case study reinforces the importance of a sound conceptual design for achieving robustness in tall timber buildings.
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Lateral stiffening systems for tall timber buildings – tube-in-tube systems

https://research.thinkwood.com/en/permalink/catalogue3268
Year of Publication
2022
Topic
Mechanical Properties
Application
Wood Building Systems
Author
Binck, Charles
Sixie, Alex
Frangi, Andrea
Organization
ETH Zurich
Publisher
Taylor&Francis Online
Year of Publication
2022
Format
Journal Article
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Tall Timber Buildings
Tube-in-tube Systems
Wind-induced Vibrations
Moment-resisting Joints
Serviceability Limit State
Research Status
Complete
Series
Wood Material Science & Engineering
Summary
In this paper, an adaptable and architecturally flexible lateral stiffening system for tall timber buildings between 50 and 147 m is developed and investigated. The system is based on a tube-in-tube concept. The internal tube consists of a braced timber core, and the external tube consists of a frame structure with semi-rigid beam-column joints in the façade. Based on a finite element framework, more than 500 000 simulations with different configurations are carried out to assess the performance of the lateral stiffening system subjected to wind loading. The resulting data is used to assess the feasibility of the tube-in-tube system and stiffness requirements for the beam-column joints.
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Micro-notches as a novel connection system for timber-concrete composite slabs

https://research.thinkwood.com/en/permalink/catalogue2841
Year of Publication
2021
Topic
Connections
Mechanical Properties
Design and Systems
Material
DLT (Dowel Laminated Timber)
Timber-Concrete Composite
Application
Floors
Author
Müller, Katharina
Frangi, Andrea
Organization
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
DLT (Dowel Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Connections
Mechanical Properties
Design and Systems
Keywords
Connection Systems
Experimental Investigations
Sustainable Construction
Micro-notches
Research Status
Complete
Series
Engineering Structures
Summary
Timber-concrete composite slabs are more and more in use: the combination of timber and concrete combines the advantages of both materials and offer a valid solution for the increasing demand for sustainable construction. The connection between timber and concrete is the crucial element, yet its potential regarding material and time expenses is not exploited. This paper presents the novel connection system micro-notches, an interlocking concept between timber and concrete with indentations in the millimetre range. Micro-notches provide a continuous shear transfer without additional steel fasteners such as screws or dowels. The paper presents the development of the micro-notch concept in an extensive experimental program supplemented with analytical and numerical models, a calculation model, and practice-relevant guidelines. The results of the investigations show that micro-notches feature an approximately rigid composite action between timber and concrete and a sufficient shear strength for the use in office and residential buildings.
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A holistic framework for designing for structural robustness in tall timber buildings

https://research.thinkwood.com/en/permalink/catalogue2853
Year of Publication
2021
Topic
Design and Systems
Material
Other Materials
Application
Wood Building Systems
Author
Voulpiotis, Konstantinos
Köhler, Jochen
Jockwer, Robert
Frangi, Andrea
Organization
ETH Zurich
National Technical University of Norway
Chalmers University of Technology
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
Other Materials
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Robustness
Tall Timber Buildings
Disproportionate Collapse
Reliability
System Effects
Research Status
Complete
Series
Engineering Structures
Summary
With the ever-increasing popularity of engineered wood products, larger and more complex structures made of timber have been built, such as new tall timber buildings of unprecedented height. Designing for structural robustness in tall timber buildings is still not well understood due the complex properties of timber and the difficulty in testing large assemblies, making the prediction of tall timber building behaviour under damage very difficult. This paper discusses briefly the existing state-of-the-art and suggests the next step in considering robustness holistically. Qualitatively, this is done by introducing the concept of scale, that is to consider robustness at multiple levels within a structure: in the whole structure, compartments, components, connections, connectors, and material. Additionally, considering both local and global exposures is key in coming up with a sound conceptual design. Quantitatively, the method to calculate the robustness index in a building is presented. A novel framework to quantify robustness and find the optimal structural solution is presented, based on the calculation of the scenario probability-weighted average robustness indices of various design options of a building. A case study example is also presented in the end.
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Long-term deformation behaviour of timber columns: Monitoring of a tall timber building in Switzerland

https://research.thinkwood.com/en/permalink/catalogue2881
Year of Publication
2021
Topic
Serviceability
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Columns
Author
Jockwer, Robert
Grönquist, Philippe
Frangi, Andrea
Organization
Chalmers University of Technology
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Columns
Topic
Serviceability
Keywords
Creep
Rheological Material Behaviour
Long-term Behaviour
Research Status
Complete
Series
Engineering Structures
Summary
Knowledge on the short and long term deformation behavior of highly loaded components in tall timber buildings is important in view of improving future design possibilities with respect to serviceability, both in the construction and in the operational state. In this paper, we present the results of a monitoring case-study on a tall timber-hybrid building in Switzerland, a 15 storey and 60 m high office building completed in 2019. A fibre-optic measuring system showed an increase of the deformation with increasing load during the construction phase of highly stressed spruce-GLT and beech-LVL columns. However, the highest strain values were not reported in the columns themselves but at the ceiling transitions and in the area near their supports. The measurements on the columns were compared with model calculations for long-term deformation of timber elements in order to differentiate single components of the total deformation caused by load, time, and changes in climate during the construction. Over a monitoring period of a year, good agreement of the modelled deformations could be confirmed, which indicates that such models could be well suited for future usage in serviceability design of tall timber buildings.
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Experimental analysis of cross-laminated timber rib panels at normal temperature and in fire

https://research.thinkwood.com/en/permalink/catalogue2933
Year of Publication
2021
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Author
Kleinhenz, Miriam
Just, Alar
Frangi, Andrea
Organization
ETH Zurich
Tallinn University of Technology
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Topic
Fire
Keywords
Timber Composite Structures
Massive Timber Rib Panel
Fire Resistance
ISO Fire Exposure
Glue Line Quality
Effective Width
Research Status
Complete
Series
Engineering Structures
Summary
The results of an experimental programme on the structural behaviour, fire behaviour, and fire resistance of CLT rib panels are presented. The floor system consists of cross-laminated timber (CLT) plates rigidly bonded to glued-laminated timber ribs by means of screw-press gluing. The experimental programme comprised ultimate-load tests at normal temperature as reference tests and full-scale fire resistance tests on four cross-sections. In addition to the reference tests, shear tests of the glue line between CLT plate and glued-laminated timber rib were performed for analysis of the cross-sections’ composite action. The results of the reference tests show good agreement with results based on the simplified method according to EN 1995-1-1 [1] and its final draft of CLT design [2]. The importance of the glue line’s quality was confirmed. The fire resistance tests show results on the safe side compared to predictions of the fire behaviour according to EN 1995-1-2 [3] and its actual draft [4]. However, the fire resistance was underestimated due to conservative assumptions about the composite cross-section’s structural behaviour. The experimental programme addressed the fire behaviour and fire resistance of CLT rib panels currently not covered in standards. The project’s overall aim is the development of design rules in fire for EN 1995-1-2.
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Self-camber of timber beams by swelling hardwood inlays for timber–concrete composite elements

https://research.thinkwood.com/en/permalink/catalogue2950
Year of Publication
2021
Topic
Mechanical Properties
Moisture
Material
Timber-Concrete Composite
Application
Beams
Author
Müller, Katharina
Grönquist, Philippe
Cao, Alex
Frangi, Andrea
Organization
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
Timber-Concrete Composite
Application
Beams
Topic
Mechanical Properties
Moisture
Keywords
Self-Camber
Swelling
Serviceability Limit State
European Beech
Research Status
Complete
Series
Construction and Building Materials
Summary
Timber–concrete composites (TCC) are smart solutions for slabs in residential and office buildings regarding the sustainable and performance-optimized use of materials. However, a non-negligible disadvantage is the deflection of the timber elements caused by in-situ concrete casting during construction. This paper presents an approach to camber timber elements without external forces by using the innate swelling capacity of wood. Oven-dried hardwood inlays can be inserted transversally into cuts on the top side of a timber element. After an increase of the moisture content in the inlays, the swelling pressure will result in a self-camber of the timber element. In this study, a procedure for prediction of the self-camber is derived and the model is validated using an experimental test series. The results demonstrate that the self-camber of spruce elements using beech inlays is both feasible and predictable. On this basis, practical application scenarios for TCC elements in timber engineering are shown and discussed.
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Structural Fire Design-Statement on the Design of Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue2398
Year of Publication
2019
Topic
Fire
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Schmid, Joachim
Werther, Norman
Klippel, Michael
Frangi, Andrea
Organization
ETH Zurich
Publisher
Juniper Publishers
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Fire
Design and Systems
Keywords
Fire Safe Design
Fire Characteristics
Building Codes
Research Status
Complete
Series
Civil Engineering Research Journal
Summary
Recently, some comments about Cross-Laminated Timber (CLT) appeared in journals, online press and lobby documents that highlighted “inconsistencies” of the product when it comes to its fire safe use. The actual document summarizes relevant fire characteristics of CLT, which were brought up, and addresses them accordingly with respect to common understanding, established experience, European standardization and available design guidance. This document shows that currently fire design is not fully covered by codes, but safe design is possible using additional sources as guideline and state of the art documents. The authors of this document share the opinion with CEN/TC 250/SC5/WG4 that fire safe design of CLT is achieved when actual state of the art guidance is followed.
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An Improved Model for the Fire Design of Cross Laminated Timber in Bending

https://research.thinkwood.com/en/permalink/catalogue1940
Year of Publication
2018
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Author
Schmid, Joachim
Klippel, Michael
Fahrni, Reto
Frangi, Andrea
Tiso, Mattia
Just, Alar
Werther, Norman
Organization
ETH Zurich
Tallinn University of Technical
Technical University Munich
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Keywords
Fire Resistance
Model
Zero-Strength Layer
Cross-Section
Bending
Strength
Stiffness
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 20-23, 2018, Seoul, Republic of Korea
Summary
In this study, new design models for cross-laminated timber (CLT) are developed to verify the fire resistance up to 120 minutes. This is done aiming for the popular Effective Cross-Section Method using a so-called zero-strength layer (ZSL) to account for losses in strength and stiffness. This was done using a method earlier presented at WCTE 2010 and discussed with the European industry. To allow for improvements, (a) the current CLT product portfolio was analysed and thermal and mechanical simulations were done accordingly for initially unprotected and unprotected members. Further, (b) new definitions for the ZSL were used to allow for a higher accuracy of the simplified models. As anoutcome, a model with (1) tabulated data between 7.0 and 12.0 mm for the effective ZSL only considering longitudinal layers and (2) a simplified model “twelve and two” is proposed for CLT members in bending.
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Assessing the Adhesive Performance in CLT Exposed to Fire

https://research.thinkwood.com/en/permalink/catalogue1945
Year of Publication
2018
Topic
Connections
Fire
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Klippel, Michael
Schmid, Joachim
Fahrni, Reto
Frangi, Andrea
Organization
ETH Zurich
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Connections
Fire
Keywords
Adhesive
Fire Tests
Polyurethane
1C PUR
Melamine Urea Formaldehyde
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
Cross-laminated timber (CLT) became a popular engineered wood product in recent years for highquality and innovative timber buildings. As for any building product, the fire behaviour of CLT panels requires careful evaluation in the design of such buildings. The adhesive used in the bond lines of CLT plays an important role in the fire design. However, currently, European standards do not provide a test method to assess the adhesive performance in CLT exposed to fire. This paper presents a series of fire tests performed with CLT panels glued with different adhesives. It is shown how the mass loss of the CLT panels in standard fire resistance tests can be used to assess the adhesive performance in CLT exposed to fire.
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30 records – page 1 of 3.