Durability and protection of mass timber structures: A review

2021 ◽  
pp. 103731
Author(s):  
Samuel Ayanleye ◽  
Kenneth Udele ◽  
Vahid Nasir ◽  
Xuefeng Zhang ◽  
Holger Militz
Keyword(s):  
Timber Structures ◽  
Mass Timber

Structural Systems for Mass Timber Buildings

2019 ◽  
Author(s):  
Tim Gleason ◽  
Gordana Herning ◽  
John Klein
Keyword(s):  
Affordable Housing ◽  
Lateral Force ◽  
Timber Structures ◽  
Braced Frames ◽  
Conventional Concrete ◽  
Composite Systems ◽  
Lateral Resistance ◽  
Mass Timber ◽  
Story Building ◽  
Gravity System

<p>This paper investigates the design of lateral force resisting systems (LFRS) for multi-story mass timber structures in Boston, MA. Structural and environmental tradeoffs of replacing conventional concrete cores or steel braced frames with glue-laminated timber (GLT) braced frames are evaluated through numerical analyses of 8-, 12-, and 18-story building prototypes. Finding an optimal timber gravity system configuration is followed by examining lateral resistance of the prototypes. The resulting designs demonstrate a practical approach to assist designers in selecting a lateral system during the early stages of conceptual design. This research was conducted in parallel with a related study for implementation of mass timber in affordable housing in Boston, enabling a comparison between composite systems and all-timber structures.</p>

scholarly journals Analysis of hygroscopic self-shaping wood at large scale for curved mass timber structures

2019 ◽  
Vol 5 (9) ◽  
pp. eaax1311 ◽  
Author(s):  
Philippe Grönquist ◽  
Dylan Wood ◽  
Mohammad M. Hassani ◽  
Falk K. Wittel ◽  
Achim Menges ◽  
...  
Keyword(s):  
Large Scale ◽  
Manufacturing Industry ◽  
Deformation Mechanisms ◽  
Timber Structures ◽  
Geometric Complexity ◽  
Wood Structures ◽  
Material Parameters ◽  
Industrial Manufacturing ◽  
Shape Prediction ◽  
Mass Timber

The growing timber manufacturing industry faces challenges due to increasing geometric complexity of architectural designs. Complex and structurally efficient curved geometries are nowadays easily designed but still involve intensive manufacturing and excessive machining. We propose an efficient form-giving mechanism for large-scale curved mass timber by using bilayered wood structures capable of self-shaping by moisture content changes. The challenge lies in the requirement of profound material knowledge for analysis and prediction of the deformation in function of setup and boundary conditions. Using time- and moisture-dependent mechanical simulations, we demonstrate the contributions of different wood-specific deformation mechanisms on the self-shaping of large-scale elements. Our results outline how to address problems such as shape prediction, sharp moisture gradients, and natural variability in material parameters in light of an efficient industrial manufacturing.

scholarly journals DURABILITY OF MASS TIMBER STRUCTURES: A REVIEW OF THE BIOLOGICAL RISKS

2018 ◽  
Vol 50 (Special) ◽  
pp. 110-127 ◽  
Author(s):  
J.Y. Wang ◽  
R Stirling ◽  
Paul I. Morris ◽  
A. Taylor ◽  
J. Lloyd ◽  
...  
Keyword(s):  
Timber Structures ◽  
Mass Timber

Mass Timber: Looking Back to Effectively Look Forward

2019 ◽  
Author(s):  
Nat Oppenheimer
Keyword(s):  
The United States ◽  
Hybrid Structures ◽  
Timber Structures ◽  
Structural Element ◽  
High Profile ◽  
The Past ◽  
Industrial Structures ◽  
Timber Construction ◽  
Research Initiatives ◽  
Mass Timber

<p>The use of mass timber as a structural element is not a new phenomenon. For example, within almost every major city in the world, there are upscale enclaves centered around the adaptive reuse of factories and warehouses from the late 19th and early 20th centuries. These former industrial structures are almost always constructed from masonry and mass timber.</p><p>Within the past decade, the building industry has seen a renewed interest in mass timber structures. This resurgence has been fueled by several trends, including the mass production of Cross Laminated Timber (CLT) and a growing awareness of mass timber’s sustainable advantages. A number of high-profile heavy timber structures have found commercial success in the United States and abroad. Leading architectural practices such as Skidmore Owings &amp; Merrill (SOM) have used research initiatives like the Timber Tower Research Project to jump-start a fertile debate within the design industry. On the demand side, building owners have pushed the design community to find innovative ways to incorporate mass timber into their projects.</p><p>This interest has often driven designers and builders to aggressively distinguish their projects from predecessors, pushing for pure mass timber structures while giving less consideration to hybrid structures (mass timber and masonry/concrete structures). This bias towards material purity risks ignoring important lessons from the past and may in some cases lead to inefficient structural choices and structures with less durability and sustainability than their hypothetical hybrid counterparts.</p><p>This paper posits that some of the energy generated by a resurgence in mass timber construction would be well spent on understanding, celebrating, and rediscovering the elegance and importance of hybrid structures.</p>

Enhanced Seismic Systems for Mass-Timber Structures

2019 ◽  
Author(s):  
Mark Sarkisian ◽  
Rupa Garai ◽  
Benton Johnson ◽  
Chris Horiuchi
Keyword(s):  
Base Material ◽  
Shear Walls ◽  
Timber Structures ◽  
Residual Drift ◽  
Moment Resisting ◽  
Recovery Times ◽  
Carbon Mass ◽  
Renewable Material ◽  
Friction Surfaces ◽  
Mass Timber

<p>Mass-timber provides numerous benefits in reducing structural material impact on the environment by limiting building embodied carbon. Mass timber from sustainably harvested farms is a renewable material and considered a sink from wood carbon sequestration, and the reduced weight of mass timber framed buildings results in less lateral system and foundation materials.</p><p>Timber’s limited ductility and traditional connections limit applications in high-seismic regions, but a series of novel connections can reliably provide ductility by using friction to dissipate energy, protecting timber elements as they remain essentially elastic. The bolted connections are designed to be easily replaceable after an earthquake and can re-center the building under any residual drift. In these systems, the seemingly incompatible concepts of resilient and sustainable design can be achieved concurrently, using a renewable material for the base material and connections which specifically target faster recovery times.</p><p>The Pin-Fuse® Joint and Link-Fuse™ Joint systems, used in moment resisting timber frames and cross- laminated timber shear walls systems, rely on slipping of pre-tensioned bolts across friction surfaces to simulate material yielding. This paper will review the theory behind the systems, application of the devices in timber structures, and compare enhanced seismic design to conventional design timber buildings.</p>

Mass-Timber Structures—Increased Ductility through Friction Mechanism

AEI 2019 ◽  
2019 ◽  
Author(s):  
M. Sarkisian ◽  
R. Garai ◽  
B. Johnson ◽  
C. Horiuchi
Keyword(s):  
Timber Structures ◽  
Friction Mechanism ◽  
Mass Timber

scholarly journals Numerical Modelling Analysis of Angle Bracket Connections Used in Cross Laminated Timber Constructions

2019 ◽  
pp. 421-428
Author(s):  
Saeed Rezvani ◽  
Lina Zhou
Keyword(s):  
Failure Modes ◽  
Numerical Models ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Load Resistance ◽  
Timber Structures ◽  
Cross Laminated Timber ◽  
Finite Element Software ◽  
Modelling Analysis ◽  
Mass Timber

Connections are arguably one of the most critical components controlling the structural performance and failure modes of mass timber structures. Over the last two decades, demands for stronger and energy dissipative connections have been raised with increased application of mass timber products in larger and taller buildings. This paper presents numerical analyses of novel mass timber connections used in cross laminated timber structures. The connections are developed by MyTiCon with BB Stanz- und Umformtechnik GmbH angle bracket. Despite being relatively thin, these angle brackets could show comparable load resistance with thicker ones due to the reinforced web and folded edges. The commercially available finite element software ABAQUS was used to develop three dimensional (3D) numerical models to simulate the performance of angle bracket connections under different load combinations. The modelling analysis involves two phases: (1) to determine the most efficient fastener type and setup for the angle brackets connected to CLT wall and floor panels, and (2) to evaluate the capacity of angle brackets connected to CLT wall and floor panels in various loading scenarios. The findings of this study provide an insight into the behaviour of this new angle bracket connections and will be used in the design of the experimental tests in the next phase.

scholarly journals Structural Timber Design in Curricula of Canadian Universities: Current Status and Future Needs

2021 ◽  
Vol 11 (12) ◽  
pp. 765
Author(s):  
Hossein Daneshvar ◽  
Tahiat Goni ◽  
Sigong Zhang ◽  
Reed Kelterborn ◽  
Ying Hei Chui
Keyword(s):  
Civil Engineering ◽  
Quantitative Information ◽  
Structural Timber ◽  
Current Status ◽  
Timber Structures ◽  
Next Generation ◽  
Engineering Programs ◽  
Canadian Universities ◽  
Modern Mass ◽  
Mass Timber

Due to the efficiency, sustainability, and advances in firefighting technologies, the allowable height for wood buildings was increased from 4 to 6 storeys in 2015 and will be further increased to 12 storeys in the 2020 edition of the National Building Code of Canada, as a result of the advent and application of mass timber products. To match the development in the industry and the increasing need in the market for highly skilled timber engineers, structural timber design curricula at the university level must evolve to train the next generation of practitioners. At most Canadian universities, structural timber design courses are mainly provided in civil engineering departments. In this study, 31 accredited civil engineering programs in Canada were reviewed for structural wood design content at undergraduate and graduate levels based on two surveys conducted in 2018 and 2020. In the 2018 survey, the percentage of structural timber design content was estimated and compared with other engineering materials (e.g., steel, concrete, and masonry), and a similar survey was repeated in 2020 to determine if any significant changes had occurred. In early 2021, two complementary questionnaires were sent to the instructors of timber-related courses across the country to collect quantitative information, including enrollment statistics, percentage dedicated to timber design in combined material courses, and potential topics deemed critical to support the design of modern timber structures. Based on the responses provided, and also on the availability of resources and the research ongoing, the content for five advanced-level courses is proposed to address the needs of the timber design community. The findings presented in this paper will assist the timber industry, government agencies, and educational institutions in effecting potential changes to university curricula to educate the next generation of timber design professionals who will possess the necessary skills and knowledge to meet the challenges in designing modern mass timber structures.

A Summary Report on Second World War Activity at Watery Lane, Church Crookham, Hampshire

2019 ◽  
Vol 74 (1) ◽  
pp. 170-176
Author(s):  
Matt Nichol
Keyword(s):  
Second World War ◽  
Late Prehistoric ◽  
Timber Structures ◽  
Summary Report ◽  
World War ◽  
Archaeological Excavation ◽  
Field Boundary ◽  
Development Area ◽  
Five Phases ◽  
Second World

An archaeological excavation of four areas approximately 0.39ha in total, of land at Watery Lane, Church Crookham, Hampshire, was undertaken by Cotswold Archaeology in November and December 2016. It followed the recording of two Pill Boxes and a trial trench evaluation of a wider development area. In all four areas archaeological features were identified. The artefactual evidence indicated five phases of archaeological activity, with features dating from the late prehistoric, medieval, medieval/post-medieval, and post-medieval to modern wartime period. Several heavily truncated isolated prehistoric features were identified, as were field boundary ditches of medieval to the post-medieval date. Many undated, but presumed modern, postholes were found across the site. The postholes may have been the result of an extensive network of Second World War temporary timber structures known as tactical obstacles (including barbed wire entanglements and tank proof obstacles) erected during anti-invasion defence works. These structures were likely to have been part of the important Stop Line Defence network, Line A of the GHQ (General Headquarters) line of defences, which were planned to slow down a ground invasion.

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