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48 records – page 1 of 5.

Contemporary and Novel Hold-Down Solutions for Mass Timber Shear Walls

https://research.thinkwood.com/en/permalink/catalogue2941
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Tannert, Thomas
Loss, Cristiano
Organization
University of Northern British Columbia
University of British Columbia
Editor
Tullini, Nerio
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Mechanical Properties
Keywords
Self-Tapping Screws
Internal-Perforated Steel Plates
Hyperelastic Bearing Pads
Proprietary Connections
Research Status
Complete
Series
Buildings
Summary
‘Mass timber’ engineered wood products in general, and cross-laminated timber in particular, are gaining popularity in residential, non-residential, as well as mid- and high-rise structural applications. These applications include lateral force-resisting systems, such as shear walls. The prospect of building larger and taller timber buildings creates structural design challenges; one of them being that lateral forces from wind and earthquakes are larger and create higher demands on the ‘hold-downs’ in shear wall buildings. These demands are multiple: strength to resist loads, lateral stiffness to minimize deflections and damage, as well as deformation compatibility to accommodate the desired system rocking behaviour during an earthquake. In this paper, contemporary and novel hold-down solutions for mass timber shear walls are presented and discussed, including recent research on internal-perforated steel plates fastened with self-drilling dowels, hyperelastic rubber pads with steel rods, and high-strength hold-downs with self-tapping screws.
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Effects of Ground Motion Duration on the Seismic Performance of a Two-Storey Balloon-Type CLT Building

https://research.thinkwood.com/en/permalink/catalogue3154
Year of Publication
2022
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Jafari, Maral
Pan, Yuxin
Shahnewaz, Md
Tannert, Thomas
Organization
University of Northern British Columbia
Fast + Epp
Editor
Bento, Rita
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Keywords
Ground Motion
Collapse Capacity
Dynamic Analysis
Research Status
Complete
Series
Buildings
Summary
The effects of long duration ground motions on the seismic performance of a newly constructed two-storey balloon-type cross-laminated timber (CLT) building located in Vancouver, Canada, was studied. A three-dimensional numerical model of the building was developed in OpenSees. The connection and shear wall models were validated with test data. Twenty-four pairs of long and short duration records with approximately the same amplitude, frequency content, and rate of energy build-up were used for nonlinear dynamic analyses. Fragility curves were developed based on the results of incremental dynamic analysis to assess the building’s collapse capacity. At design intensity level, ground motion duration was shown not to be a critical factor as the difference in inter-storey drift ratio between the two sets of records was negligible. However, due to the larger number of inelastic cycles, the long duration motions increased the median probability of collapse by 9% when compared with the short duration motions. Further research is required to evaluate the duration effects on taller and platform-type CLT buildings.
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Finite element analysis of alternative load paths to prevent disproportionate collapse in platform-type CLT floor systems

https://research.thinkwood.com/en/permalink/catalogue2901
Year of Publication
2021
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Huber, Johannes
Bita, Hercend
Tannert, Thomas
Berg, Sven
Organization
Luleå University of Technology
University of Northern British Columbia
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Design and Systems
Keywords
Mass Timber
Structural Robustness
High Fidelity Model
Progressive Collapse
Structural Integrity
Component Model
Research Status
Complete
Series
Engineering Structures
Summary
Multi-storey buildings require mitigation of consequences of unexpected or accidental events, to prevent disproportionate collapse after an initial damage. Cross-laminated timber (CLT) in platform-type construction is increasingly used for multi-storey buildings, however, the collapse behaviour and alternative load paths (ALPs) are not fully understood. A 3D non-linear component-based finite element model was developed for a platform-type CLT floor system to study the ALPs after an internal wall loss, in a pushdown analysis. The model, which accounted for connection failure, timber crushing and large displacements, was calibrated to experimental results and then adapted for boundary conditions corresponding to typical residential and office buildings. Subsequently, five parameters (floor span, connection type, vertical location of the floor, tying level, horizontal wall stiffness) were varied, to study their effects on the ALPs in 80 models. The results showed that three ALPs occurred, of which catenary action was the most dominant. Collapse resistance was mainly affected by the floor span, followed by the axial strength, stiffness and ductility of the floor-to-floor connection, the weight of the level above and the floor panel thickness. This study provides an approach to model ALPs in a platform-type CLT floor system to design disproportionate collapse resistant multi-storey CLT buildings.
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Experimental Investigations of Full-Scale Cross-Laminated Timber Concrete Composite Floors

https://research.thinkwood.com/en/permalink/catalogue3351
Year of Publication
2021
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Shahnewaz, Md
Jackson, Robert
Tannert, Thomas
Organization
Fast + Epp
University of Northern British Columbia
Publisher
Springer
Year of Publication
2021
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Self-tapping screw
Steel Kerf Plates
Glued-in Holz-Beton-Verbund (HBV) Plates
Conference
Proceedings of the Canadian Society of Civil Engineering Annual Conference 2021
Research Status
Complete
Notes
Page 401
Summary
Experimental investigations on full-scale Timber Concrete Composite (TCC) floor systems with various composite connectors are presented in this paper. The stiffness, strength, and failure modes of were evaluated. The 9.2 m long and 2.4 m wide TCC floor segments were comprised of 245 mm thick, 7-ply Cross-laminated Timber (CLT) panels with 150 mm concrete topping connected with three types of shear connectors: (i) self-tapping screws, (ii) steel kerf plates, and (iii) glued-in Holz-Beton-Verbund (HBV) plates. Six TCC floor segments were tested to failure under symmetric four-point bending and three TCC floor segments were tested under torsional bending by applying eccentric loading near the edge. The floor deformations at nine locations and connector slips at CLT-concrete interfaces at eight locations along the length of the floor were measured. The full-scale tests showed that the steel kerf plates—for the selected connector configurations- exhibited the highest capacity and stiffness.
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Internal Perforated-steel-plate Connections with Self-Drilling Dowels for Cross-laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2807
Year of Publication
2020
Topic
Connections
Seismic
Wind
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Drexler, Maximilian
Tannert, Thomas
Organization
University of Northern British Columbia
Year of Publication
2020
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Seismic
Wind
Keywords
Lateral Load Resisting System
Shear Walls
CSA 086
Internal-Perforated-Steel-Plates
Self-drilling Dowels
Research Status
Complete
Summary
Cross-laminated timber (CLT) constitutes a promising solution for numerous structural applications, including for large and tall residential and commercial buildings. The prospect of building larger timber structures creates some structural challenges, amongst them being that lateral forces created by high winds and strong earthquakes are higher and create higher demands of “holddowns”. The Canadian Standard for Engineering Design in Wood CSA-O86 does not (yet) provide any specific procedures to estimate the resistance of mass-timber Lateral Load Resisting Systems (LLRS) nor how to facilitate the targeted kinematic mode, especially for multi-panel walls where the LLRS behaviour is a function of connection behaviour. The project investigated the viability of internal-perforated-steel-plates (ISP) with self-drilling dowels as high-performance connections for CLT LLRS. The project objective was to contribute towards the development of reliable design guidance for ISP connections. To achieve this objective, first at the material level, the properties of the used steel-plates and dowels were verified. Then, at the component level, the performance of shear connections and hold-downs were investigated by performing quasi-static monotonic and reversed cyclic tests. The most significant finding of the component level tests was the proof that it is possible to control the strength, stiffness, and ductility only through the IPSP and avoid bending of the SDD or crushing of the wood. Furthermore, the length of the steel perforations had a large impact on the performance with the steel-plates with the long slots (Type-D and Type-E) exhibiting lower strength and stiffness. For the hold-down tests, the same perforation geometry as for the shear-connection tests was chosen. As already determined in the shear-connection tests, the hold-down specimens with the short perforation slots resulted in the strongest and stiffest connection. The results from this project will be used to design and test CLT shear walls with ISP connections.
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Serviceability Performance of Timber Concrete Composite Floors

https://research.thinkwood.com/en/permalink/catalogue2353
Year of Publication
2019
Topic
Serviceability
Material
Timber-Concrete Composite
Application
Floors
Author
Tannert, Thomas
Mehdi Ebadi, Md
Gerber, Adam
Year of Publication
2019
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Serviceability
Keywords
Hybrid
Concrete Slab
Bending
Vibration
Long-term Performance
Stiffness
Research Status
Complete
Series
Modular and Offsite Construction (MOC)
Notes
DOI: https://doi.org/10.29173/mocs95
Summary
There is much potential for engineered wood products to be used beyond low-rise residential construction when incorporating the notion of hybrid systems like timber-concrete-composites (TCC). TCC systems are comprised of a timber element connected to a concrete slab through a shear connection. By combining the complimentary properties of timber and concrete, the performance of timber floors can be enhanced, including bending stiffness, load-bearing capacity, dynamic response, airborne sound transmission, structural fire rating, and thermal mass. A large number of T-beam TCC systems existed for decades; however, the growing availability of panel-type products in North America offers designers greater versatility in terms of structural and building physics performance. While stiffness and strength design of TCC systems is straight-forward, there is little design guidance available in terms of vibration and long-term performance. The bending, vibration and long-term performance for a range of TCC systems in several EWPs were validated on small-scale shear tests, floor panels subjected to serviceability loads for 2.5 years, and subsequent full-size bending tests. The tests confirmed that calculations according to the Gamma-method can predict the basic stiffness and dynamic properties of TCC floors within a reasonable degree of accuracy.
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Lateral Performance of Cross-laminated Timber Shear Walls: Analytical and Numerical Investigations

https://research.thinkwood.com/en/permalink/catalogue2425
Year of Publication
2019
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Shahnewaz, Md
Tannert, Thomas
Popovski, Marjan
Organization
University of Northern British Columbia
FPInnovations
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Design and Systems
Keywords
Lateral Loading
Shear Walls
Platform Construction
Finite Element Model
Kinematic Rocking Behaviour
Research Status
Complete
Series
Modular and Offsite Construction (MOC) Summit Proceedings
Summary
Cross-laminated timber (CLT) is becoming a viable option for mid-rise buildings in North America. CLT walls are very effective in resisting lateral forces resulting from wind and seismic loads, yet no standard provisions are available to estimate the resistance of CLT shear walls under lateral loading. The present research investigated CLT shear wall’s performance by evaluating the preferred kinematic rocking behaviour. An analytical procedure was proposed to estimate the resistance of CLT shear walls in a platform type construction. Finite element models of CLT shear with various brackets and hold-downs connections were developed. The models were validated against experimental results. Furthermore, a parametric study on CLT shear walls with the variation of type and number of connectors was conducted. The resistance estimated from parametric study and against analytical were compared. The proposed formulas can be useful tool for the design of CLT platform-type buildings, however, require further experimental validation.
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Feasibility Study of Mass-Timber Cores for the UBC Tall Wood Building

https://research.thinkwood.com/en/permalink/catalogue1895
Year of Publication
2018
Topic
Design and Systems
Environmental Impact
Seismic
Wind
Material
LVL (Laminated Veneer Lumber)
Application
Shafts and Chases
Author
Connolly, Thomas
Loss, Cristiano
Iqbal, Asif
Tannert, Thomas
Publisher
MDPI
Year of Publication
2018
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Application
Shafts and Chases
Topic
Design and Systems
Environmental Impact
Seismic
Wind
Keywords
Student Residence
Inter-Storey Drift
Environmental Footprint
Building Codes
Research Status
Complete
Series
Buildings
Summary
The UBC Brock Commons building in Vancouver, which comprises of 18 stories and stands 53 m in height, was at the time of completion in 2016 the world’s tallest hybrid wood-based building. The building’s 17 stories of mass-timber superstructure, carrying all gravity loads, rest on a concrete podium with two concrete cores that act as both the wind and seismic lateral load-resisting systems. Whereas the construction of the concrete cores took fourteen weeks in time, the mass-timber superstructure took only ten weeks from initiation to completion. A substantial reduction in the project timeline could have been achieved if mass-timber had been used for the cores, leading to a further reduction of the building’s environmental footprint and potential cost savings. The objective of this research was to evaluate the possibility of designing the UBC Brock Commons building using mass-timber cores. The results from a validated numerical structural model indicate that applying a series of structural adjustments, that is, configuration and thickness of cores, solutions with mass-timber cores can meet the seismic and wind performance criteria as per the current National Building Code of Canada. Specifically, the findings suggest the adoption of laminated-veneer lumber cores with supplementary ‘C-shaped’ walls to reduce torsion and optimize section’s mechanical properties. Furthermore, a life cycle analysis showed the environmental benefit of these all-wood solutions.
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Hybrid CLT-Based Modular Construction Systems for Prefabricated Buildings

https://research.thinkwood.com/en/permalink/catalogue1901
Year of Publication
2018
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Wood Building Systems
Floors
Walls
Author
Loss, Cristiano
Tannert, Thomas
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Steel-Timber Composite
Application
Wood Building Systems
Floors
Walls
Topic
Design and Systems
Keywords
Hybrid Structures
Composite Structures
Diaphragms
Connections
Push-Out Tests
Bending Tests
Full-Scale
Sustainability
Conference
International Association for Bridge and Structural Engineering Symposium
Research Status
Complete
Notes
September 19-21, 2018, Nantes, France
Summary
Contemporary structures are required to be earthquake-resistant, sustainable and flexible to changing occupancy needs over time. Hybrid wood-based construction systems are promising solutions for modern buildings and research for cost-efficient systems is underway to compete with more traditional and widely spread non-wood building systems. This paper presents an innovative modular and prefabricated wood-based hybrid construction technology. It is a dry solution obtained by fastening on-site steel frames and composite CLT-steel members using only bolts and screws. The main results obtained from a comprehensive experimental programme with focus on the in-plane and out-of-plane behaviour of floors are reviewed. The influence of connections on the response of floors is discussed. The findings are of practical relevance with direct impacts on other applications.
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Free
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Feasibility of Cross-Laminated Timber Cores for the UBC Tall Wood Building

https://research.thinkwood.com/en/permalink/catalogue1905
Year of Publication
2018
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Shafts and Chases
Author
Connolly, Thomas
Moudgil, Manu
Loss, Christiano
Iqbal, Asif
Tannert, Thomas
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shafts and Chases
Topic
Design and Systems
Keywords
Brock Commons
Hybrid
Environmental Footprint
Seismic Performance
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 20-23,2018. Seoul, Republic of Korea
Summary
The innovation in tall mass-timber buildings is illustrated by the Brock Commons student residence at the University of British Columbia also known as the UBC Tall Wood Building. It is amongst the world’s tallest timber hybrid building with 18 stories and 53 meters’ height. The building has 17 stories of mass-timber superstructure resting on a concrete podium with two concrete cores that act as a lateral force resisting system for earthquake and wind forces. Construction of the mass-timber superstructure took ten weeks whereas the concrete cores were built in fourteen weeks. There could have been a substantial reduction in the project timeline leading to cost savings, as well as a further reduction of environmental footprint if mass-timber had been used for the cores. The objective of this work was to evaluate the possibility to design the UBC Tall Wood Building using mass-timber cores. A validated numerical model was used to study the feasibility of replacing the concrete cores by cores made of Cross Laminated Timber (CLT). The results presented herein show that, with adjustments in the configuration, the structure can meet the seismic performance criteria as per the Canadian code with CLT cores.
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48 records – page 1 of 5.