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Nonlinear FE-analysis and testing of light-frame timber shear walls subjected to cyclic loading

https://research.thinkwood.com/en/permalink/catalogue3253
Year of Publication
2023
Topic
Mechanical Properties
Author
Kuai, Le
Ormarsson, Sigurdur
Vessby, Johan
Organization
Linnaeus University
Karlstad University
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Topic
Mechanical Properties
Keywords
Finite Element Modeling
Light-frame Shear Walls
Numerical Model
Elasto-plastic Connectors
Research Status
Complete
Series
Construction and Building Materials
Summary
Light-frame timber shear walls have been used as load-bearing elements in buildings for several decades. To predict the performance of such structural elements under loading, numerous analytical and numerical models have been developed. However, little focus has been on the prediction of the plastic damage behaviour and unloading of the walls. In this paper, a parametric Finite Element (FE) model is further developed by introducing elasto-plastic connectors to simulate the mechanical behaviour of the sheathing-to-framing connections. To verify the accuracy of the elasto-plastic model, full-size walls were tested and compared with results from simulations. The numerical results, from a few loading cycles, indicate that the model achieves reasonable accuracy in predicting both the nonlinear elastic and plastic deformations. Both experimental and simulation results demonstrate the importance of opening locations relating to the external racking force. The results also indicate that for a double-layer wall, its racking strength can be achieved by summation of the separate contribution from each layer. Furthermore, the internal layer was observed to contribute significantly less than the external layer since its nail pattern was based on the sheathing pattern of the external layer.
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Analysis and enhancement of the new Eurocode 5 formulations for the lateral elastic deformation of LTF and CLT walls

https://research.thinkwood.com/en/permalink/catalogue3311
Year of Publication
2023
Topic
Mechanical Properties
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Aloisio, Angelo
Boggian, Francesco
Sævareid, Håkon Østraat
Bjørkedal, Johan
Tomasi, Roberto
Organization
Norwegian University of Life Sciences
Università degli Studi di Trento
Università degli Studi dell’Aquila
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Design and Systems
Keywords
Light Timber Frames
Lateral Deformation
Shear Walls
Eurocode 5
Finite Element Modelling
Research Status
Complete
Series
Structures
Summary
This paper analyses the analytical formulations for the lateral elastic deformation of Light Timber Framed (LTF) and Cross-Laminated Timber (CLT) shear walls according to the new Eurocode 5 (EC5) proposal. Finite Element (FE) models and the Standard predictions are compared by emphasizing the role of each deformation contribution. A total of 1830 comparisons between analytical and numerical estimations are carried out by exploiting the Application Programming Interface of SAP2000 to modify the FE model parameters automatically. The parametric analyses proved that the numerical and analytical predictions are pretty consistent. Furthermore, in both LTF and CLT shear walls, the estimates for in-plane shear and rigid body sliding are in excellent agreement. Conversely, the analytical formulas for kinematic rocking are generally conservative for LTF and monolithic CLT shear walls, with an approximate 18%–19% discrepancy. The analytical expressions of the upcoming EC5 perfectly match the numerical model for segmented CLT shear walls under lateral forces and no vertical load. However, the presence of the vertical load determines a significant bias. Additionally, the predictions for bending deformations are not in good agreement. Therefore, the paper discusses possible enhancements for the equations proposed in the next generation of Eurocodes for the rocking deformation of segmented CLT walls to better conform with FE predictions.
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Analysis Behavior of Openings on Full-Size Cross-Laminated Timber (CLT) Frame Shear Walls Tested Monotonically

https://research.thinkwood.com/en/permalink/catalogue3335
Year of Publication
2023
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Dungani, Rudi
Sulistyono
Karliati, Tati
Suhaya, Yoyo
Malik, Jamaludin
Alpian
Supriyati, Wahyu
Organization
Institut Teknologi Bandung
Kuningan University
Palangka Raya University
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Monotonic Test
Seismic Resistance
Wood-Frame
Opening
Research Status
Complete
Series
Forests
Summary
Walls, as components of the lateral-force-resisting system of a building, are defined as shear walls. This study aims to determine the behavior of shear wall panel cross-laminated-timber-based mangium wood (Acacia mangium Willd) (CLT-mangium) in earthquake-resistant prefabricated houses. The earthquake performance of CLT mangium frame shear walls panels has been studied using monotonic tests. The shear walls were constructed using CLT-mangium measuring 2400 mm × 1200 mm × 68 mm with various design patterns (straight sheathing, diagonal sheathing/45°, windowed shear wall with diagonal pattern and a door shear wall with a diagonal pattern). Shear wall testing was carried out using a racking test, and seismic force calculations were obtained using static equivalent earthquake analysis. CLT-mangium sheathing installed horizontally (straight sheathing) is relatively weak compared to the diagonal sheathing, but it is easier and more flexible to manufacture. The diagonal sheathing type is stronger and stiffer because it has triangulation properties, such as truss properties, but is more complicated to manufacture (less flexible). The type A design is suitable for low-intensity zones (2), and types B, D, E1 and E2 are suitable for moderate-intensity zones (3, 4), and type C is suitable for severe-intensity zones (5).
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Experimental investigations of a new highly ductile hold-down with adaptive stiffness for timber seismic bracing walls

https://research.thinkwood.com/en/permalink/catalogue3370
Year of Publication
2023
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Maître, K.
Lestuzzi, P.
Geiser, M.
Organization
Bern University of Applied Sciences
École Polytechnique Fédérale de Lausanne
Publisher
Springer
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Hold-Down
Adaptative Stiffness
Buckling Restrained Brace
Capacity Design
CLT Shear Wall
High Ductility
Research Status
Complete
Series
Bulletin of Earthquake Engineering
Summary
An efficient implementation of the capacity design requires high ductility combined with a low overstrength of the critical regions. Conventional timber connections do not generally offer such ideal combination, resulting in modest behaviour and relatively high overstrength factors. Inspired by the Buckling Restrained Brace a new hold-down has been developed where the timber wall directly acts as a casing. The new hold-down has been given an adaptive stiffness allowing the structure to be stiff in the wind, while becoming more flexible in the case of an earthquake. Furthermore, local crushing of the timber members is completely avoided, and the new hold-down could be replaced after an earthquake. Experimental investigations were performed on hold-down specimens. The results show ultimate displacement values vu,c of more than 30 mm in a cyclic test according to EN12512. Eleven Cross Laminated Timber shear walls, in which the new hold-down has been implemented, were tested following monotonic and static-cyclic tests procedures, with and without vertical load. A very high ductility has been achieved with almost no strength degradation, little pinching and limited overstrength.
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Modeling of Cross-Laminated Timber (CLT) panels loaded with combined out-of-plane bending and compression

https://research.thinkwood.com/en/permalink/catalogue2842
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Author
Huang, Zirui
Huang, Dongsheng
Chui, Ying Hei
Shen, Yurong
Daneshvar, Hossein
Sheng, Baolu
Chen, Zhongfan
Organization
Southeast University
University of Alberta
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Topic
Mechanical Properties
Keywords
Rolling Shear
Beam-and-Column
Analytical Model
Load-Carrying Capacity
Research Status
Complete
Series
Engineering Structures
Summary
Rolling shear is one of the major concerns that significantly impact the performance of CLT walls if they are subjected to combined out-of-plane bending and compression loads. Because the effects of rolling shear and out-of-plane bending are coupled to each other, prediction of the load-carrying capacity of CLT wall is always a challenge for the design of CLT structures. Current design codes employ an Ayrton-Perry type interaction equation as the failure criterion to check the safety of a CLT panel loaded with combined bending and compression. Nevertheless, there is no model available to predict their load-carrying capacity. The presented work aims at developing an analytical model to predict the load-carrying capacity of CLT wall loaded with combined out-of-plane bending and compression. In total 12 five-layer CLT panels loaded with different initial load eccentricities were tested to investigate the failure modes. Observed during the test were two ultimate failure modes, i.e., compression crush on the concave side and tension rupture in convex side. Based on these failure modes and deeming the test member as a beam-column, an analytical model which takes rolling shear effects into account to predict the load-carry capacity of CLT compression-bending members was developed. An explicit formula based on compression failure mode was proposed. The model is capable of determining the distribution of rolling shear stress along longitudinal direction, rolling shear-induced axial force and moments in CLT beam-columns. By calculating the load-carrying capacities of the specimens tested in this study as well as the additional three- and seven-layer specimens tested by another studies, it was found that the compression failure mode-based formula can provide good agreements with the test results.
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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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Mechanical Behavior of GFRP Dowel Connections to Cross Laminated Timber-CLT Panels

https://research.thinkwood.com/en/permalink/catalogue2957
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Almeida, Amanda
Moura, Jorge
Organization
Maringá State University
Londrina State University
Editor
Knapic, Sofia
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Connections
Keywords
GFRP
Dowel-Type Connections
Panel-to-Panel
Design Methodology
Push-Out Tests
Research Status
Complete
Series
Forests
Summary
Sustainability issues are driving the civil construction industry to adopt and study more environmentally friendly technologies as an alternative to traditional masonry/concrete construction. In this context, plantation wood especially stands out as a constituent of the cross-laminated timber (CLT) system, laminated wood glued in perpendicular layers forming a solid-wood structural panel. CLT panels are commonly connected by screws or nails, and several authors have investigated the behavior of these connections. Glass-fiber-reinforced polymer (GFRP) dowels have been used to connect wooden structures, and have presented excellent performance results; however, they have not yet been tested in CLT. Therefore, the objective of this study is to analyze the glass-fiber-reinforced polymer (GFRP)-doweled connections between CLT panels. The specimens were submitted to monotonic shear loading, following the test protocol described in EN 26891-1991. Two configurations of adjacent five-layer panels were tested: flat-butt connections with 45° dowels (x, y, and z axes), and half-lap connections with 90° dowels. The results were evaluated according to the mechanical connection properties of strength, stiffness, and ductility ratio. The results showed higher stiffness for butt-end connections. In terms of strength, the half-lap connections were stronger than the butt-end connections.
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A numerical and experimental investigation of non-linear deformation behaviours in light-frame timber walls

https://research.thinkwood.com/en/permalink/catalogue3022
Year of Publication
2022
Topic
Mechanical Properties
Application
Walls
Shear Walls
Author
Kuai, Le
Ormarsson, Sigurdur
Vessby, Johan
Maharjan, Rajan
Organization
Linnaeus University
Karlstad University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Application
Walls
Shear Walls
Topic
Mechanical Properties
Keywords
Timber Structures
Internal Force Distribution
Light-frame Shear Walls
Parametric Study
Openings
Research Status
Complete
Series
Engineering Structures
Summary
In recent decades, there is a trend in Scandinavian countries to build multi-storey residential houses using prefabricated timber modules. It is a highly efficient construction process with less environmental impact and less material waste. A significant building element in the timber modules is the light-frame timber wall, which has to be carefully analysed and optimized in this process. This paper presents a new parametric Finite Element (FE) model that can simulate both in-plane and out-of-plane deformations in the light-frame walls. A new and flexible (Eurocode based) approach to define the properties of the mechanical connections is introduced. A numerical model is presented through simulations of several walls that were verified with full-scale experiments. The results indicate that the numerical model could achieve fairly reasonable accuracy with the new approach. Furthermore, several parametric studies are presented and discussed from global and local points of view, to investigate the effects of certain parameters that are not considered in the design method according to Eurocode 5.
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Performance of midply shear wall

https://research.thinkwood.com/en/permalink/catalogue3037
Year of Publication
2022
Topic
Mechanical Properties
Fire
Acoustics and Vibration
Application
Shear Walls
Author
Ni, Chui
Dagenais, Christian
Qian, Cheng
Hu, Lin
Organization
FPInnovations
Year of Publication
2022
Format
Report
Application
Shear Walls
Topic
Mechanical Properties
Fire
Acoustics and Vibration
Keywords
Midply Shear Wall
Structural Performance
Fire Performance
Acoustic Performance
Research Status
Complete
Summary
Midply shear wall, which was originally developed by researchers at Forintek Canada Corp. (predecessor of FPInnovations) and the University of British Columbia, is a high-capacity wood-frame shear wall system that is suitable for high wind and seismic loadings. Its superior seismic performance was demonstrated in a full-scale earthquake simulation test of a 6-storey wood-frame building in Japan (Peietal.,2010). Midply shear wall, however, had limited applications due to its low resistance to vertical load and difficulty to accommodate electrical and plumbing services. For broader applications of Midply shearwall, these limitations needed to be addressed. In collaboration with APA–The Engineered Wood Association and the American Wood Council (AWC), a new framing arrangement was designed to increase the vertical load resistance of Midply shearwalls and make it easier to accommodate electrical and plumbing services. Consequently, structural, fire and acoustic tests have been conducted to evaluate various performance attributes of Midply shear wall with the new framing configuration. This InfoNote provides a summary of the structural, fire and acoustic performance of Midply shearwalls from the tests.
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Innovations in mass timber lateral systems

https://research.thinkwood.com/en/permalink/catalogue3099
Year of Publication
2022
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Bailey, Dawson
Organization
Kansas State University
Year of Publication
2022
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Rocking Timber Walls
Lateral Systems
Post Tensioning
Research Status
Complete
Summary
As mass timber becomes increasingly popular in the United States and around the world, there comes more demand for mass timber in larger buildings. With this demand comes a necessity for these buildings to be able to withstand seismic forces; and in some locations, these forces can get quite high. Typical mass timber lateral systems (such as CLT shear walls) have worked fine for lower seismic forces and shorter buildings, but with this new demand comes a need for newer systems. Rocking timber walls is one of these systems. The goal of a rocking timber wall is to allow the lateral wall system to move in the case of high seismic force, thus reducing the loading the wall experiences. This is done with vertical post tensioning (PT) within cross-laminated timber panels (CLT). In addition, easily replaceable energy dissipation devices, such as U-shaped flexural plates (UFPs), allow for concentration of inelastic deformation during rocking of the walls, which keeps the CLT and PT components free from harm. Another system used to handle seismic load in tall mass timber structures are inter-story isolation systems. These systems can isolate the force at separate levels, effectively decreasing the load the foundation takes from the building's movement. Even newer than these systems is the Floor Isolated Re-centering Modular Construction System (FIRMOC), which utilizes rocking timber walls, inter-story isolation, and the addition of prefabricated modular mass timber to create a system capable of effectively and efficiently dealing with large seismic forces. This report seeks to present these innovative, capable, and effective lateral systems for seismic forces in large scale mass timber structures in a manner that provides understanding of how they work and what makes them effective.
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Seismic performance evaluation of innovative balloon type CLT rocking shear walls

https://research.thinkwood.com/en/permalink/catalogue3133
Year of Publication
2022
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Yang, T.Y.
Lepine-Lacroix, S.
Guerrero, J.A. Ramos
McFadden, J.B.W.
Al-Janabi, M.A.Q.
Organization
The University of British Columbia
National Research Council Canada
Al-Nahrain University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Rocking Shear Walls
CLT Shear Walls
Seismic Performance
Nonlinear Finite Element Model
Research Status
Complete
Series
Resilient Cities and Structures
Summary
Balloon type cross laminated timber (CLT) rocking shear walls are a novel seismic force resisting system. In this paper, the seismic performance of four 12-story balloon type CLT rocking shear walls, designed by a structural engineering firm located in Vancouver (Canada) using the performance-based design procedure outlined in the technical guideline published by the Canadian Construction Materials center (CCMC)/National Research Council Canada (NRC), is assessed. The seismic performance of the prototype CLT rocking shear walls was investigated using nonlinear time history analyses. Robust nonlinear finite element models were developed using OpenSees and the nonlinear behavior of the displacement-controlled components was calibrated using available experimental data. A detailed site-specific hazard analysis was conducted and sets of ground motions suitable for the prototype buildings were selected. The ground motions were used in a series of incremental dynamic analyses (IDAs) to quantify the adjustable collapse margin ratio (ACMR) of the prototype balloon type CLT rocking shear walls. The results show that the prototype balloon type CLT rocking shear walls designed using the performance-based design procedure outlined in the CCMC/NRC technical guideline have sufficient ACMR when compared to the acceptable limits recommended by FEMA P695.
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Experimental Investigation of Cross Laminated Timber Elements with Holes or Notches at In-Plane Beam Loading Conditions

https://research.thinkwood.com/en/permalink/catalogue3152
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Jelec, Mario
Damjanovic, Domagoj
Varevac, Damir
Rajcic, Vlatka
Organization
Josip Juraj Strossmayer University of Osijek
University of Zagreb
Editor
Brandner, Reinhard
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
In-Plane
Hole
Notch
Crossing Area
Research Status
Complete
Series
Buildings
Summary
Environmental and urbanisation challenges have encouraged steady growth of mass timber structures where cross laminated timber (CLT) stands out in applications as full-size wall, floor, or beam elements. Beam elements are used mainly in situations where cross layers have a reinforcing effect on the tensile stress perpendicular to the beam axis, such as when introducing holes or notches, which is common practice in beams, due to engineering, installation, or architectural requirements. This paper presents experimental investigations of CLT beams with holes or notches for comparison and validation of an analytical model provided in the literature. Different sizes of holes and notches as well as different placements of the holes were considered in the experiments. All relevant failure modes were analysed and discussed in detail. Two predominant failure modes were indicated, i.e., bending failure and shear failure in crossing areas (mode III). Results further indicate that reduced lamination widths near the hole, notch, or element edges have a relatively small influence on the beam strength. Parametric studies indicate net shear failure (mode II) and tensile failure perpendicular to the beam axis as the critical failure modes in most of the considered cases, indicating their strong underestimation in design verifications according to the analytical model.
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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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Practical Modeling Approaches for Buildings with Mass Timber Lateral Systems

https://research.thinkwood.com/en/permalink/catalogue3169
Year of Publication
2022
Topic
Seismic
Application
Shear Walls
Organization
Colorado School of Mines
Year of Publication
2022
Application
Shear Walls
Topic
Seismic
Keywords
Numerical Modeling
Modeling Guide
Post-tensioned Rocking Wall Lateral Systems
Performance-Based Seismic Design
Research Status
In Progress
Notes
Project contact is Shiling Pei (United States)
Summary
This project is aimed at meeting the needs of mass timber design industry by developing a numerical modeling guide for multi-story wood buildings with post-tensioned rocking wall lateral systems. Through close collaboration of researchers, practicing engineers, and software developers, three main deliverables will be generated from this project. The first one is a tall wood modeling guide which provide detailed suggestions on mass timber building modeling options and processes using commercial programs widely available in design offices. One or multiple of PERFORM-3D, ETABS and SAP2000 packages will be used in this study. The second deliverable will be a mass timber dynamic response validation data package based on full-scale dynamic testing results from two- and ten-story mass timber buildings. This package contains building design detail and dynamic test responses, which can be used by design engineers to validate their own numerical model for performance-based seismic design or approval for new mass timber projects. Finally, the third deliverable will be a show-case archetype building modeling example in which a 6-story office building will be designed and modeled for a high seismic region location. The example will demonstrate typical steps a design engineer can follow to design and model such a building for review and approval by building officials.
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A unified design proposal for shear stress prediction in crossing areas for cross laminated timber at in-plane shear and beam loading conditions

https://research.thinkwood.com/en/permalink/catalogue3186
Year of Publication
2022
Topic
Design and Systems
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams
Walls
Author
Danielsson, Henrik
Jelec, Mario
Organization
Lund University
Josip Juraj Strossmayer University of Osijek
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Beams
Walls
Topic
Design and Systems
Mechanical Properties
Keywords
Unified Design Proposal
Crossing Area
In-Plane Shear
Research Status
Complete
Series
Construction and Building Materials
Summary
Environmental and urbanization challenges during the last few decades encouraged steady growth of mass timber construction where attention is drawn to cross laminated timber (CLT) as one of the most interesting products in terms of mechanical properties, versatility, efficient prefabrication and sustainability. Standardisation and codification regarding testing and design of CLT elements are hence pointed out as one of the main issues within the ongoing revision procedure of Eurocode 5. A consistent and unified design approach for CLT at pure in-plane shear loading conditions (shear walls) and at in-plane beam loading conditions is however still missing. This paper deals with analytical models for the determination of stress components related to predictions of load bearing capacity of CLT with respect to shear failure mode III – shear failure in the crossing areas constituted by the flatwise bonded areas between laminations of adjacent layers. This failure mode is relevant for both pure in-plane shear loading and in-plane beam loading conditions. The paper presents a review of previously proposed models for the prediction of shear stresses in crossing areas of CLT, for both loading conditions. Comparisons between FE-results and model predictions are reviewed indicating significant differences between them concerning the predicted influence of the CLT element lay-up and values of maximum shear stresses. Based on simplifications of models previously presented, a unified design proposal that is based on a rational and consistent mechanical background for both loading situations and that shows overall good agreement with FE-results is presented.
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The Dimensional Stability and Bonding Performance of Hybrid CLT Fabricated with Lumber and COSB

https://research.thinkwood.com/en/permalink/catalogue3195
Year of Publication
2022
Topic
Moisture
Application
Floors
Walls
Author
Liang, Zhijun
Chen, Guojun
Wang, Yi
Wang, Zhiqiang
Gong, Meng
Organization
Nanjing Forestry University
University of New Brunswick
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Application
Floors
Walls
Topic
Moisture
Keywords
Hybrid Cross Laminated Timber
Construction Oriented Strand Board
Dimensional Stability
Bonding Performace
Delamination
Research Status
Complete
Series
Buildings
Summary
The differences of physical and mechanical properties of different laminations, such as softwood, hardwood or other structural composite lumber, in hybrid cross-laminated timber (HCLT), lead to their dimensional stability and bonding performance more complex than generic cross-laminated timber (CLT). In this paper, the spruce-pine-fir (SPF) dimension lumber and construction oriented strand board (COSB) were employed to fabricate HCLT. The effects of four configurations and three adhesives on the dimensional stability and bonding performance of CLT and HCLT were evaluated in term of the water absorption (WA), thickness swelling (TS), block shear strength (BSS), wood failure percentage (WFP) and rate of delamination (RD). The results showed that with the increase of the COSB laminations, the WA of HCLT specimens decreased, and the values of TS, BBS and WFP increased. The configuration had a significant influence on the dimensional stability, BBS and WFP of the specimen. The adhesive had a significant influence on the dimensional stability and some bonding performances of the specimen. The phenol resorcinol formaldehyde (PRF) specimens had the lowest average RD value compared with the one-component polyurethane (PUR) and emulsion polymer isocyanate (EPI) specimens. Failures were prone to occur in the middle of the thickness of COSB lamination during block shear and delamination tests. The outcome of this paper could help the engineering application of HLCT.
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Determination of seismic performance factors for cross-laminated timber shear walls based on FEMA P695 methodology

https://research.thinkwood.com/en/permalink/catalogue3215
Year of Publication
2022
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Lindt, John van de
Amini, M. Omar
Rammer, Douglas
Line, Philip
Pei, Shiling
Popovski, Marjan
Organization
Forest Products Laboratory
Year of Publication
2022
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Seismic Design
Mass Timber Design
FEMA P695
Research Status
Complete
Summary
Cross-laminated timber (CLT) construction has been gaining popularity in North America. However, CLT-based seismic force resisting systems are not recognized in current U.S. design codes, which is among the many challenges preventing widespread adoption of CLT in the United States. The purpose of this study was to investigate the seismic behavior of CLT-based shear wall systems and to determine seismic performance factors, namely, the response modification factor (R factor), the system overstrength factor(O), and the deflection amplification factor (Cd), using the FEMA P695 procedure. Nine index buildings including single-family dwellings, multifamily dwellings, and commercial (including mixed use) midrise buildings were developed, from which 72 archetypes were extracted. Testing performed at the component and subassembly levels included connector tests and isolated shear wall tests. A CLT shear wall design method was developed and used to design the archetypes, which were then assessed with nonlinear pushover analysis and incremental dynamic analysis. Based on the required collapse margin, an R factor of 3 is proposed for CLT shear wall systems with 2:1 or mixed aspect ratio panels up to 4:1, and an R factor of 4 is proposed for CLT shear wall systems made up of only 4:1 aspect ratio panels. Results from this study have been proposed for recognition in U.S. building codes (such as the International Building Code) through specific change proposals to update reference standards such as ASCE 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures and Special Design Provisions for Wind and Seismic.
Online Access
Free
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The wall–frame interaction effect in CLT-steel hybrid system

https://research.thinkwood.com/en/permalink/catalogue3260
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Frames
Shear Walls
Author
Vogiatzis, Tzanetis
Tsalkatidis, Themistoklis
Efthymiou, Evangelos
Organization
Aristotle University of Thessaloniki
Norwegian University of Life Sciences
Publisher
Frontiers
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Frames
Shear Walls
Topic
Mechanical Properties
Keywords
Steel-moment Resisting Frame
Steel-timber Hybrid Structure
Seismic Behavior
Numerical Analysis
Ductility
Research Status
Complete
Series
Frontiers in Built Environment
Summary
Behaviour and capacity of cross-laminated timber (CLT) infills built inside steel frames have been given increasing research attention in recent years. It is widely accepted that when the CLT wall panel is built in tight contact with the bounding steel frame to participate in the load sharing, its inherently large in-plane stiffness will attract additional forces to the frame area and change the behaviour of the hybrid system. If not designed properly, the structural integrity of both the infill and the frame will be compromised. It is thus crucial to accurately evaluate the contribution of the infill CLT wall panel to the stiffness and strength of the hybrid system. To that end, a finite element study was performed to investigate the frame-wall interaction effect on the behaviour of hybrid systems. The lateral stiffness, lateral load capacities and hysteretic characteristics of the hybrid systems with frictional and connected interfaces were investigated. The load-sharing effect between the CLT wall and the steel frame was studied. The numerical results showed that the connected models were very effective as the infill absorbed a substantial part of the lateral load, during the initial stages of loading.
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Free
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Experimental and analytical study of Friction Connection for seismic retrofit with Cross-Laminated Timber (CLT) panels

https://research.thinkwood.com/en/permalink/catalogue3366
Year of Publication
2022
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Boggian, Francesco
Aloisio, Angelo
Tomasi, Roberto
Organization
Norwegian University of Life Sciences
University of Trento
University of L’Aquila
Publisher
Wiley Online Library
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Friction Connection
Energy Dissipation
Renovation
Research Status
Complete
Series
Earthquake Engineering & Structural Dynamics
Summary
Within the European project e-SAFE (Energy and Seismic AFfordable rEnovation solutions), this paper presents the experimental tests and modeling attempts for a class of Asymmetric Friction Connections (AFCs) tested in the laboratories of the Norwegian University of Life Sciences. The AFCs are part of the seismic retrofitting solution, called e-CLT, based on installing Cross-Laminated Timber (CLT) panels in reinforced concrete structures using friction connections. The authors carried out experimental tests on AFCs fixed with screws to a CLT panel to observe the contribution of timber to the total dissipation performance. The investigation is based on 20 cyclic test data with two different setups. The main one includes a CLT panel and screw connection, while the second one isolates the friction behaviour to evaluate the influence of the screw connection. A modified LuGre hysteresis model for friction is developed to simulate the experimental cyclic response of the tested specimen. The model possesses a direct physical meaning, and it explicitly depends on the slip force and the pre-slip stiffness. The optimized model is used to assess the performance of the AFC by varying the pre-slip stiffness and the slip force.
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Free
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Pinching Effect on Seismic Performance of a SDOF Lightframe Timber Structure

https://research.thinkwood.com/en/permalink/catalogue2542
Year of Publication
2021
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Shear Walls
Author
Eini, Ariya
Zhou, Lina
Ni, Chun
Organization
University of Victoria
Year of Publication
2021
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Shear Walls
Topic
Seismic
Keywords
Pinching Behavior
Energy Dissipation
Hysteresis Loop
Light-frame wood
IDA Analysis
SDOF System
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
Although energy dissipation is one of the key factors in resisting seismic force, current design codes only take into account the ductility of the backbone properties of hysteresis curves, and the energy dissipation is usually not accounted for. This paper focuses on understanding and assessing the influence of energy dissipation due to different pinching levels on the seismic performance of a light-frame wood shear wall system. Timber structures with identical backbone curves but different pinching levels were analyzed. Incremental dynamic analyses were run on a single-degreeof-freedom system with varying pinching stiffness and residual strength. The seismic evaluation is presented by the spectral accelerations causing failure of the structure and the hysteresis energy dissipation under a suite of 22 ground motions (2 components per motion) over a wide range of fundamental periods of typical timber structures. Results show that the effect of pinching on the seismic performance of timber structures is period-dependent. Short period structures are more sensitive to the pinching of hysteresis loops compared to long period structures. The residual strength of pinching loops has a greater influence on the seismic performance than the stiffness of the pinching loops. Hysteretic energy dissipation derived from standard reversed-cyclic tests can provide a better understanding on the seismic resistance of timber structures. However, the hysteretic energy under a seismic event at near-collapse stage neither agrees with quasistatic cyclic test’s energy dissipation nor is well correlated to the maximum seismic capacity of the structure.
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Free
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