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Diaphragmatic Behaviour of Hybrid Cross-Laminated Timber Steel Floors

https://research.thinkwood.com/en/permalink/catalogue2039
Year of Publication
2018
Topic
Design and Systems
Mechanical Properties
Seismic
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Author
Loss, Cristiano
Gobbi, Filippo
Tannert, Thomas
Organization
University of Northern British Columbia
University of Trento
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Topic
Design and Systems
Mechanical Properties
Seismic
Keywords
Numerical Model
In-Plane Stiffness
Aspect Ratio
Load Distribution
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
The diaphragmatic behaviour of floors represents one important requirement for earthquake resistant buildings since diaphragms connect the lateral load resisting systems at each floor level and transfer the seismic forces to them as a function of their in-plane stiffness. This paper presents an innovative hybrid timber-steel solution for floor diaphragms developed by coupling cross-laminated timber panels with cold-formed custom-shaped steel beams. The floor consists of prefabricated repeatable units which are fastened on-site using pre-loaded bolts and self-tapping screws, thus ensuring a fast and efficient installation. An experimentally validated numerical model is used to evaluate the influence of the; i) in-plane floor stiffness; ii) aspect ratio and shape of the building plan; and iii) relative stiffness and disposition of the shear walls, on the load distribution to the shear walls. The load transfer into walls and lateral deformation of the construction system primarily depend on the adopted layouts of shear walls, and for most cases an in-plane stiffness of floors two times larger than that of walls is recommended.
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Nonlinear Static Seismic Response of a Building Equipped with Hybrid Cross-Laminated Timber Floor Diaphragms and Concentric X-Braced Steel Frames

https://research.thinkwood.com/en/permalink/catalogue2761
Year of Publication
2021
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Author
Roncari, Andrea
Gobbi, Filippo
Loss, Cristiano
Organization
University of British Columbia
University of Trento
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Floors
Topic
Seismic
Keywords
Seismic Design
Hybrid Structures
Lateral Resistance
Semi-rigid Diaphragms
Load Distribution
Seismic Performance
Pushover Analysis
Nonlinear Static Analysis
Finite Element Model
Research Status
Complete
Series
Buildings
Summary
Simplified seismic design procedures mostly recommend the adoption of rigid floor diaphragms when forming a building’s lateral force-resisting structural system. While rigid behavior is compatible with many reinforced concrete or composite steel-concrete floor systems, the intrinsic stiffness properties of wood and ductile timber connections of timber floor slabs typically make reaching a such comparable in-plane response difficult. Codes or standards in North America widely cover wood-frame construction, with provisions given for both rigid and flexible floor diaphragms designs. Instead, research is ongoing for emerging cross-laminated-timber (CLT) and hybrid CLT-based technologies, with seismic design codification still currently limited. This paper deals with a steel-CLT-based hybrid structure built by assembling braced steel frames with CLT-steel composite floors. Preliminary investigation on the performance of a 3-story building under seismic loads is presented, with particular attention to the influence of in-plane timber diaphragms flexibility on the force distribution and lateral deformation at each story. The building complies with the Italian Building Code damage limit state and ultimate limit state design requirements by considering a moderate seismic hazard scenario. Nonlinear static analyses are performed adopting a finite-element model calibrated based on experimental data. The CLT-steel composite floor in-plane deformability shows mitigated effects on the load distribution into the bracing systems compared to the ideal rigid behavior. On the other hand, the lateral deformation always rises at least 17% and 21% on average, independently of the story and load distribution along the building’s height.
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Free
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On the distribution of internal forces in single-storey CLT symmetric shear-walls with openings

https://research.thinkwood.com/en/permalink/catalogue2850
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Casagrande, Daniele
Fanti, Riccardo
Greco, Marco
Gavric, Igor
Polastri, Andrea
Organization
Institute of Bioeconomy - National Research Council of Italy
University of Trento
University of Primorska
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Mechanical Properties
Keywords
Shear Walls
Openings
Stress Distribution
Finite Element Modeling
Research Status
Complete
Series
Structures
Summary
This paper presents a numerical and analytical study on single-storey cross-laminated timber (CLT) shear-walls with openings subjected to lateral loads. The main objective was to investigate the location and distribution of maximum values of axial and shear forces in relevant wall sections. The influence of parameters such as wall geometry (different sizes of wall openings, door openings, lintel/parapet lengths and heights, wall thickness) and different stiffness levels of mechanical anchors for CLT wall connection with floor/foundation were studied. Finite element (FE) parametric analyses were performed on a set of single-storey CLT shear-walls with door and window openings and were compared with analytical models for determination of internal forces. The importance of wall connections’ flexibility was identified, as the distribution of internal forces in walls with rigid and flexible anchors were considerably different. The obtained outcomes of this study provide a solid base for the next step, an experimental investigation of in-plane internal force distribution in CLT walls with openings, which will serve for further development of numerical, analytical and design approaches.
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The role of the hold-down in the capacity model of LTF and CLT shear walls based on the experimental lateral response

https://research.thinkwood.com/en/permalink/catalogue2849
Year of Publication
2021
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Shear Walls
Author
Aloisio, Angelo
Boggian, Francesco
Tomasi, Roberto
Fragiacomo, Massimo
Organization
Università degli Studi dell'Aquila
University of Trento
Norwegian University of Life Science
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Shear Walls
Topic
Mechanical Properties
Connections
Keywords
Hold-Down
Rocking
Cyclic Response
Shear Walls
Light-frame wood
Research Status
Complete
Series
Construction and Building Materials
Summary
Cross Laminated Timber (CLT) and Light Timber Frame (LTF) shear walls are widespread constructive technologies in timber engineering. Despite the intrinsic differences, the lateral response of the two structural systems may be quite similar under specific connection layouts, boundary constraints, and size of the shear walls. This paper compares the experimental cyclic responses of CLT and LTF shear walls characterized by the same size 250×250cm, and loaded according to the EN 12512 protocol. The rigid-body rotation of the shear walls prevails over the deformation and rigid-body translation in the post-elastic displacement range. As a consequence, a capacity model of the two systems based on the sole hold-down response accurately seizes the observed cyclic response, despite ignoring the other resisting contributions. The authors examine the differences exhibited by the CLT and LTF shear walls and the related error corresponding to a capacity model based on the sole hold down restraints. Additionally, it is assessed the overstrength of the CLT panel and LTF sheathing to the shear walls collapse due to the hold-down failure. The estimated overstrength factor is the most meaningful difference between the two structural systems in the considered experimental layouts.
Online Access
Free
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