Special Issue "Advances in Mass Timber and Timber Hybrid Lateral Load Resisting Systems"

A special issue of Buildings (ISSN 2075-5309).

Deadline for manuscript submissions: closed (30 September 2018)

Special Issue Editor

Guest Editor
Dr. Tannert Thomas

University of Northern British Columbia
Website | E-Mail
Interests: Wood and hybrid structures, design of wood joints and components

Special Issue Information

Dear Colleagues,

There is a great potential for timber to be used as structural material beyond the more common low-rise residential light-frame construction. The prospect of building larger timber structures comes with certain challenges, amongst them increased lateral force created by wind and earthquakes. Two of the most promising solutions to this problem involve the notions of “mass timber”, such as cross-laminated timber and hybrid constructions that strategically combine two (or more) materials, such as timber–steel and timber–concrete systems. This Special Issue will provide insight into state-of-the-art research on the challenges and innovative solutions of adopting mass timber and timber–hybrid structural systems. Considering the global need for more sustainable building solutions, this Special Issue is of international interest.

Dr. Tannert Thomas
Guest Editor

Manuscript Submission Information

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Keywords

  • Sustainable Construction
  • Lateral Load Resisting Systems
  • Mass Timber
  • Cross-Laminated Timber
  • Hybrid Structures

Published Papers (8 papers)

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Research

Open AccessArticle Numerical Study of Alternative Seismic-Resisting Systems for CLT Buildings
Buildings 2018, 8(11), 162; https://doi.org/10.3390/buildings8110162
Received: 26 September 2018 / Revised: 29 October 2018 / Accepted: 14 November 2018 / Published: 16 November 2018
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Abstract
Changes to building codes that enable use of materials such as cross-laminated timber (CLT) in mid- and high-rise construction are facilitating sustainable urban development in various parts of the world. Keys to this are the transition to multi-performance-based design approaches along with fewer
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Changes to building codes that enable use of materials such as cross-laminated timber (CLT) in mid- and high-rise construction are facilitating sustainable urban development in various parts of the world. Keys to this are the transition to multi-performance-based design approaches along with fewer limitations on heights or the number of storeys in superstructures constructed from combustible materials. Architects and engineers have increased freedom to apply new design and construction concepts and methods, as well as to combine timber with other structural materials. They also have started to develop wall arrangements that optimise interior space layouts and take advantage of the unique characteristics of CLT. This paper discusses the seismic response of multi-story buildings braced with a CLT core and perimeter shear walls anchored to foundations and floor platforms using modern high-capacity angle brackets and hold-downs, or X-Rad connectors. Linear dynamic finite element (FE) models of seismic responses of superstructures of various heights are presented, based on experimentally determined characteristics of wall anchor connections. Particular attention is given to fundamental vibration periods, base shear and uplift forces on walls, as well as inter-story drift. Discussion of FE model results focuses on structural engineering implications and advantages of using CLT to create shear walls, with emphasis on how choice of wall anchoring connections impacts the possible number of storeys and configurations of superstructures. Employing CLT shear walls with X-Rad or other types of high capacity anchoring connections makes possible the creation of building superstructures having eight and potentially more storeys even in high seismicity regions. However, it is important to emphasise that proper selection of suitable arrangements of shear walls for CLT buildings depends on accurate representation of the semi-rigid behaviors of anchoring connections. The linear dynamic analyses presented here demonstrates the need during engineering seismic design practices to avoid use of FE or other design models which do not explicitly incorporate connection flexibilities while estimating parameters like fundamental periods, base shear and uplift forces, as well as inter-story drift. Full article
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Open AccessArticle Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels
Buildings 2018, 8(10), 146; https://doi.org/10.3390/buildings8100146
Received: 21 September 2018 / Revised: 16 October 2018 / Accepted: 19 October 2018 / Published: 22 October 2018
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Abstract
The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is affected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate
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The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is affected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels. Full article
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Open AccessArticle Mechanical Properties of Innovative, Multi-Layer Composite Laminated Panels
Buildings 2018, 8(10), 142; https://doi.org/10.3390/buildings8100142
Received: 4 September 2018 / Revised: 1 October 2018 / Accepted: 10 October 2018 / Published: 12 October 2018
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Abstract
Cross-laminated timber (CLT) possesses both good shape stability and possible two-way force transfer ability due to its crosswise lamination. However, the transverse layers in CLT are prone to rolling shear failure under an out-of-plane load. An innovative multi-layer composite laminated panel (CLP) was
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Cross-laminated timber (CLT) possesses both good shape stability and possible two-way force transfer ability due to its crosswise lamination. However, the transverse layers in CLT are prone to rolling shear failure under an out-of-plane load. An innovative multi-layer composite laminated panel (CLP) was developed by combining structural composite lumber (SCL) and dimension lumber to overcome the rolling shear failure while maintaining the high mechanical performance and aesthetic appearance of natural wood. The mechanical properties of 5-layer CLP that consisted of laminated strand lumber (LSL) and dimension lumber with different layups were evaluated by both static and modal tests. The results showed that the shear resistance, bending stiffness, and moment resistance of CLP were up to 143%, 43%, and 87% higher than their counterparts of regular CLT, respectively. The failure modes observed in both shear and bending tests indicated that the use of LSL in transverse layers could eliminate the potential rolling shear failure in CLT. With the lamination properties from components tests as inputs, the validity of shear analogy method was assessed by test results. The mechanical properties can be well predicted by shear analogy method except for the bending moment resistance of CLP and CLT with either rolling failure in the cross layer or tension failure in the bottom layer. Full article
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Open AccessArticle Fire Resistance of In-Plane Compressed Log-House Timber Walls with Partial Thermal Insulation
Buildings 2018, 8(10), 131; https://doi.org/10.3390/buildings8100131
Received: 29 August 2018 / Revised: 14 September 2018 / Accepted: 18 September 2018 / Published: 21 September 2018
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Abstract
This paper presents the full-scale experimental assessment of a log-house timber wall with partial thermal insulation under in-plane compression and exposed to fire on one side. A key aspect of the current design application for log-house systems is represented by geometrical details, like
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This paper presents the full-scale experimental assessment of a log-house timber wall with partial thermal insulation under in-plane compression and exposed to fire on one side. A key aspect of the current design application for log-house systems is represented by geometrical details, like cross-sectional properties of logs (typically characterised by high depth-to-width ratios) and outriggers. The latter provides restraint condition for the examined walls and hence markedly affects their overall load-carrying capacity. As a result, careful consideration should be given to the choice of these details, compared to fully monolithic timber walls (i.e., made from cross-laminated timber), due to the possible occurrence of local structural and/or thermo-mechanical mechanisms. This is the case of exceptional loading conditions like fire load, as the fire resistance of these systems could be affected by a multitude of variables, including the presence (even though limited to few surfaces only) of thermal insulation panels. To this aim, the results of a full-scale furnace test are discussed in the paper for a log-wall with partial thermal insulation, namely thermal insulation applied on the outriggers only, under the effects of EN/ISO standard fire conditions. The results of Finite Element (FE) numerical studies are also reported, to further explore the load-carrying performance of the reference log-house specimen and compare it with the experimental observations. Several thermal insulation configurations are finally numerically investigated, showing their effects on the overall fire resistance of the assembly. In accordance with literature, the test shows that the log house’s timber wall is suitable to obtain a fire resistance of about 60 min under relevant loading. The FE results are in rather close agreement with the temperature measurements within the section of logs, as well as a qualitative correlation with respect to the mechanical behaviour observed in the full-scale furnace experiment. The key role of outriggers and their thermo-mechanical boundaries, finally, is emphasised. Full article
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Open AccessArticle The Influence of Panel Lay-Up on the Characteristic Bending and Rolling Shear Strength of CLT
Buildings 2018, 8(9), 114; https://doi.org/10.3390/buildings8090114
Received: 28 June 2018 / Revised: 14 August 2018 / Accepted: 16 August 2018 / Published: 21 August 2018
Cited by 1 | PDF Full-text (3522 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this study was to characterise the behaviour of cross laminated timber (CLT) panels and the influence of the panel lay-up on the failure strength. Three different panel configurations of thickness, 60 mm, 100 mm, and 120 mm, were loaded in
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The objective of this study was to characterise the behaviour of cross laminated timber (CLT) panels and the influence of the panel lay-up on the failure strength. Three different panel configurations of thickness, 60 mm, 100 mm, and 120 mm, were loaded in the out-of-plane direction. The 60 mm and 120 mm panel configuration comprised three layers of equal thickness, and the intermediate 100 mm thick panel comprised five layers of equal thickness. The mean and characteristic bending and rolling shear strength of the panels were examined. The results show that the mean bending and rolling shear strength decrease with the panel thickness. The characteristic results have shown that there is an influence because of the number of boards within the panel. The characteristic bending strength values for the five-layer 100 mm thick panel were found to be higher than that of the three-layer 60 mm panel. The characteristic rolling shear values decreased in the five-layer panels, however, the increased number of layers subjected to the rolling shear results in a reduced variability in the rolling shear strength. Full article
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Open AccessArticle In-Plane Strength and Stiffness of Cross-Laminated Timber Shear Walls
Buildings 2018, 8(8), 100; https://doi.org/10.3390/buildings8080100
Received: 28 June 2018 / Revised: 24 July 2018 / Accepted: 30 July 2018 / Published: 3 August 2018
Cited by 1 | PDF Full-text (3316 KB) | HTML Full-text | XML Full-text
Abstract
The research presented herein investigated the in-plane performance of cross-laminated timber (CLT) shear walls for platform-type buildings under lateral loading. Finite element models of CLT connections (i.e., brackets, hold-downs and self-tapping screws) were developed in OpenSees and calibrated against experimental tests to represent
[...] Read more.
The research presented herein investigated the in-plane performance of cross-laminated timber (CLT) shear walls for platform-type buildings under lateral loading. Finite element models of CLT connections (i.e., brackets, hold-downs and self-tapping screws) were developed in OpenSees and calibrated against experimental tests to represent the connections’ hysteresis behaviour under cyclic tension and shear loading. The results were incorporated into models of CLT single and coupled shear walls. The results in terms of peak displacement, peak load and energy dissipation were in good agreement when compared to full-scale shear wall tests. Subsequently, a parametric study of 56 single and 40 coupled CLT shear walls was conducted with varying numbers and types of connectors (wall-to-floor and wall-to-wall) for evaluating their seismic performance. It was found that the strength, stiffness and energy dissipation of the single and coupled CLT shear walls increased with an increase in the number of connectors. Single shear walls with hold-downs and brackets performed better under seismic loading compared to walls with brackets only. Similarly, coupled shear walls with four hold-downs performed better compared to walls with two hold-downs. Finally, ductility of coupled shear walls was found to be 31% higher compared to that of single shear walls. The findings from this research are useful for engineers to efficiently design CLT shear walls in platform-type construction. Full article
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Open AccessArticle Shear Performance Assessment of Timber Log-House Walls under In-Plane Lateral Loads via Numerical and Analytical Modelling
Received: 30 June 2018 / Revised: 26 July 2018 / Accepted: 31 July 2018 / Published: 1 August 2018
Cited by 2 | PDF Full-text (5113 KB) | HTML Full-text | XML Full-text
Abstract
Log-house is an ancient construction technology based on the superposition of linear timber logs, connected to the orthogonal walls by a system of carvings, notches and corner joints. Due to the fact that this solution is widely used in constructions located in seismic
[...] Read more.
Log-house is an ancient construction technology based on the superposition of linear timber logs, connected to the orthogonal walls by a system of carvings, notches and corner joints. Due to the fact that this solution is widely used in constructions located in seismic or windy areas, the in-plane behaviour of walls represents an attractive research topic. In this paper, major outcomes of a Finite-Element (FE) numerical investigation carried out on single corner joints currently in use for log-house buildings are discussed under different loading conditions (i.e., in-plane lateral and vertical compressive loads), including parametric analyses to capture the key aspects of their typical structural response. Careful consideration is paid for the elastic stiffness of such joints, being of primary interest for design purposed. At the same time, a linear analytical formulation is presented, with the aim of providing a simple but useful tool in support of design, and especially to estimate the maximum lateral displacement/resistance for a given log-house wall when subjected to in-plane lateral forces. There, the intrinsic mechanical features of corner joints and related aspects are properly considered (i.e., static friction phenomena, as well as the presence of small gaps, etc.). The analytical model, in addition, takes advantage of the numerically predicted joint stiffness values, being dependent on several parameters. As shown, rather good agreement is obtained between the FE model output, the analytical predictions and past reference experimental/numerical results available in the literature for full-scale log-house walls under in-plane lateral loads, hence suggesting the potential of the proposed approach. In conclusion, possible Force-Preload-Displacement (FPD) charts are presented, to act as simplified tools for preliminary design considerations. Full article
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Open AccessFeature PaperArticle Feasibility Study of Mass-Timber Cores for the UBC Tall Wood Building
Received: 28 June 2018 / Revised: 25 July 2018 / Accepted: 25 July 2018 / Published: 1 August 2018
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Abstract
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,
[...] Read more.
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. Full article
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