Glued laminated timber

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Glulam brace with plates used for connections Glulam.brace.png
Glulam brace with plates used for connections
Glulam frame of a roof structure Glulam.JPG
Glulam frame of a roof structure

Glued laminated timber, commonly referred to as glulam, is a type of structural engineered wood product constituted by layers of dimensional lumber bonded together with durable, moisture-resistant structural adhesives so that all of the grain runs parallel to the longitudinal axis. In North America, the material providing the laminations is termed laminating stock or lamstock.

Contents

Glulam arches of the Sheffield Winter Garden Sheffield Winter Gardens - geograph.org.uk - 702939.jpg
Glulam arches of the Sheffield Winter Garden

History

Curved glulam-framed building at the Faculty of Education, University of Cambridge. Donald Mcintyre Building, Faculty of Education, University of Cambridge.jpg
Curved glulam-framed building at the Faculty of Education, University of Cambridge.

The principles of glulam construction are believed to date back to the 1860s, in the assembly room of King Edward VI College, a school in Southampton, England. [2] The first patent however emerged in 1901 when Otto Karl Freidrich Hetzer, a carpenter from Weimar, Germany, patented this method of construction. Approved in Switzerland, Hetzer's patent explored creating a straight beam out of several laminations glued together. In 1906 he received a patent in Germany for curved sections of glulam. Other countries in Europe soon began approving patents and by 1922, glulam had been used in 14 countries.

The technology was first brought to the United States by Max Hanisch Sr., who had been associated with the Hetzer firm in 1906 before emigrating to the United States in 1923. With no financial backing, it was not until 1934 that Hanisch was able to first use glulam in the United States. The project, a school and community gym in Peshtigo, Wisconsin, took time to get started, as manufacturers were hard to find, but eventually the Thompson Brothers Boat Manufacturing Company took on the project. The Wisconsin Industrial Commission, however, rejected the arches as they had no previous experience working with glulam. A compromise was reached in which the arches could be used if they were used in conjunction with bolts, lags, metal strapping, and angles to reinforce the structure. Though the reinforcements were unnecessary, ground finally broke in late 1934 featuring four spans of three-hinged arches with clear spans of 20 metres (64 ft). The partnership for this project lead to the creation of Unit Structures Inc., a construction firm for glulam owned by both the Hanisch and Thompson families.

In 1936, Unit Structures patented both the forming equipment used to produce glulam arches and the glulam arches themselves. A second project, this time for the Forest Products Laboratory (FPL), gave Unit Structures the opportunity to prove the strength and stiffness of glulam members to architects and engineers. Full-scale load tests conducted by placing 14.3 tonnes (31,500 lb) of sandbags on the roof exceeded the design specs by 50%. The noted deflections were also in favor of the system. While the results took some time to get published, the test enabled Unit Structures to continue building with glulam. At this time, I-sections featuring plywood webs and glulam flanges became popular in Europe while rectangular sections became the norm in America. The I-sections saved on lumber, which was beneficial to Europeans as they had high lumber costs but were more labor intensive, which was expensive in the States. The glulam system piqued the interest of those on the west coast and many firms began to engage with it.

In 1942, the introduction of a fully water-resistant phenol-resorcinol adhesive enabled glulam to be used in exposed exterior environments without concern of glue line degradation, expanding its applicable market. During the midst of World War II, glulam construction became more widespread as steel was needed for the war effort. In 1952, leading fabricators of engineered and solid wood joined forces to create the American Institute of Timber Construction (AITC) to help standardize the industry and promote its use. [3] The first U.S. manufacturing standard for glulam was published by the Department of Commerce in 1963. Since then, glulam manufacturing has spread within the United States and into Canada and has been used for other structures, such as bridges, as well. It is currently standardized under ANSI Standard A190.1. [4]

Manufacturing

The manufacturing of glulam is typically broken down into four steps: drying and grading the lumber, joining the lumber to form longer laminations, gluing the layers, and finishing and fabrication. The lumber used to produce glulam may come to the manufacturers pre-dried or will have to be dried onsite. A hand-held or on the line moisture meter is used to check the moisture levels of the lumber. Each piece of lumber going into the manufacturing process should have a moisture content between 8% and 14% in accordance with the adhesive used. [5] If a piece of lumber is above this threshold it is redried.

Once the lumber is dry, knots on the ends of the lumber are trimmed and grading occurs. Lumber is then grouped based on the grade. To create lengths of glulam longer than those typically available for sawn lumber, the lumber must be end-jointed. The most common joint for this is a finger joint, 1.1 in (2.8 cm) in length that is cut on either end with special cutter heads. A structural resin, typically RF curing melamine formaldehyde (MF) or PF resin, is applied to the joint between successive boards and cured under end pressure using a continuous RF curing system. After the resins have cured, the lumber is planed on each side to ensure smooth surfaces for gluing.

Once planed, a glue extruder spreads the resin onto the lumber. This resin is most often phenol-resorcinol-formaldehyde, but PF resin or melamine-urea-formaldehyde (MUF) resin can also be used. For straight beams, the resinated lumber is stacked in a specific lay-up pattern in a clamping bed so that a mechanical or hydraulic system can press the lumber together. For curved beams, the same process occurs, but lumber is instead stacked in a curved form. These beams are cured at room temperature for 5 to 16 hours before the pressure is released unless the hydraulic pressure is combined with RF curing, which can reduce the length of time needed for curing. Once the glulam beams are completely cured, they are removed from the clamping system the wide-side faces are sanded or planed to remove any resin that is squeezed out between the boards. The narrow top and bottom faces may also be sanded if necessary, based on the desired appearance. The corners are often rounded as well. Specifications for appearance govern whether or not additional finishing is completed. Additional finishing may include filling knot holes with putty, sanding the beams further, and applying sealers, finishes, or primers. [6]

Technological developments

Resin glues

When glued laminated timber was introduced as a building material in the early twentieth century, casein glues (which are waterproof but have low shear strength) were widely used. Joints with casein glues had detachment failures due to inherent stresses in the wood. The invention of cold-curing synthetic resin glues in 1928 ("Kaurit") and other urea-formaldehyde glues solved these problems - resin glues, which are inexpensive and easy to use, are waterproof and enable high adhesive strength. The development of resin glues contributed to the wide use of glued laminated timber construction. [7]

Finger joints

The use of finger joints with glulam allowed for production of glulam beams and columns on large scale. Glulam finger joints were developed to provide broad surface area for gluing. Automatic finger-jointing machines help cut the finger joints, connect and glue them together under pressure, allowing for a strong, durable joint, capable of carrying high loads comparable to natural wood with the same cross-section. [8]

Computer numerical control

Computer numerical control (CNC) allows architects and designers to cut glued laminated timber into unusual shapes with a high degree of precision. CNC machine tools can utilize up to five axes, which enables undercutting and hollowing-out processes. The cost-effective CNC machines carve the material using mechanical tools, like a router. [9]

Advantages

There are several advantages to using glulam in construction:

Disadvantages

As with any system, there are some drawbacks to using glulam:

Applications

Sport structures

Richmond Olympic Oval Richmond Olympic Oval intern View.jpg
Richmond Olympic Oval

Sport structures are a particularly suitable application for wide-span glulam roofs. This is supported by the light weight of the material, combined with the ability to furnish long lengths and large cross-sections. Prefabrication is invariably employed, and the structural engineer needs to develop clear method statements for delivery and erection at an early stage in the design. The PostFinance Arena is an example of a wide-span sports stadium roof using glulam arches reaching up to 85 metres. The structure was built in Bern in 1967, and has subsequently been refurbished and extended. Eastern Kentucky University's Alumni Coliseum was built in 1963 with the world's largest glued laminated arches, which span 93.967 metres (308 ft 3+12 in).

The roof of the Richmond Olympic Oval, built for speed skating events at the 2010 Winter Olympic Games in Vancouver, British Columbia, features one of the world's largest clearspan wooden structures. The roof includes 2,400 cubic metres of Douglas fir lamstock lumber in glulam beams. A total of 34 yellow cedar glulam posts support the overhangs where the roof extends beyond the walls. [20]

Anaheim Ice in Anaheim, California, is also an example of using glued laminated timber. Disney Development Company desired to build an aesthetic ice rink with less cost, and glulam was one of the most qualified materials in order to meet the owner's requirement. Architect Frank Gehry suggested a design with large double-curved yellow pine glulam beams, and the ice rink was constructed in 1995. [21]

Bridges

Heavy-traffic Accoya Glulam Bridge at Sneek, the Netherlands Accoya-Glulam-Bridge.jpg
Heavy-traffic Accoya Glulam Bridge at Sneek, the Netherlands
Glulam bridge crossing Montmorency River, Quebec Wood bridge Montmorency.jpg
Glulam bridge crossing Montmorency River, Quebec

Pressure-treated glulam timbers or timbers manufactured from naturally durable wood species are well suited for creating bridges and waterfront structures. Wood's ability to absorb impact forces created by traffic and its natural resistance to chemicals, such as those used for de-icing roadways, make it ideal for these installations.

Glulam has been successfully used for pedestrian, forest, highway, and railway bridges. One North American glulam bridge is Keystone Wye in the Black Hills of South Dakota, constructed in 1967. The da Vinci Bridge in Norway, completed in 2001, is almost completely constructed with glulam. The Kingsway Pedestrian Bridge in Burnaby, British Columbia, Canada, is constructed of cast-in-place concrete for the support piers, structural steel and glulam for the arch, a post tensioned precast concrete walking deck, and stainless steel support rods connecting the arch to the walking deck.

Religious buildings

The interior of the Cathedral of Christ the Light formed with glued laminated timber Cathedral of Christ the Light in Oakland, California LCCN2013635148.tif
The interior of the Cathedral of Christ the Light formed with glued laminated timber

Glulam is used for the construction of multi-use facilities such as churches, school buildings, and libraries. The Cathedral of Christ the Light in Oakland, California, is one such example and uses glulam to enhance the ecological and aesthetic effect. It was built as the replacement of the Cathedral of Saint Francis de Sales, which became unusable after the Loma Prieta earthquake in 1989. The 2,010-square-metre (21,600 sq ft), 34-metre-high (110 ft) vesica piscis -shaped building formed the frame with a glued-laminated timber beam and steel-rod skeleton covered with a glass skin. Considering the conventional mode of construction with steel or reinforced concrete moment-frame, this glulam-and-steel combination case is regarded as an advanced way to realize the economy and aesthetic in the construction. [22]

As an alternative to new-felled oak trees, glued laminated timber was proposed as the structural material in the replacement spire of Notre-Dame de Paris , destroyed by fire in 2019. [23] [24]

Other

Mjostarnet, on the shore of Lake Mjosa. Mjostarnet.jpg
Mjøstårnet, on the shore of Lake Mjøsa.

In 2019, the world's tallest structure employing the use of glulam was Mjøstårnet, an 18-story mixed-use building in Brumunddal, Norway. [25] In 2022, the Ascent MKE building in Milwaukee, Wisconsin, surpassed it with 26 stories, measuring over 86 meters tall. [26]

The roof of the Centre Pompidou-Metz museum in France is composed of sixteen kilometers of glued laminated timber intersecting to form hexagonal units. With a surface area of 8,000 m2, the irregular geometry of the roof, featuring various curves and counter-curves, resembles a Chinese hat. [27]

Failures

In 2005, researchers at Lund University, Sweden, found a number of failures of glulam structures in Scandinavian countries. They concluded that construction faults or design errors were responsible. [28] In January 2002 the roof of the Siemens velodrome arena in Copenhagen collapsed when a joint between glulam trusses failed at the point of its dowel fastenings. [28] In February 2003 the roof of a newly built exhibition hall in Jyväskylä, Finland, collapsed. It was found that during construction the specified number of dowels at joints between glulam timbers were missing or had been wrongly placed. [28]

The collapse of the Perkolo bridge in Sjoa, Norway, in 2016 was caused by a design miscalculation of stresses at joints. [29] Following this incident thirteen road bridges of glulam construction were checked, with only minor faults found.[ citation needed ]

On 15 August 2022 Tretten Bridge in Gudbrandsdalen, Norway, collapsed as two vehicles were crossing. It was made with glulam and steel construction and had been erected in 2012, with a design life of "at least 100 years". The cause of the failure was not immediately apparent, although during the 2016 inspection (see above), one joint was found to have dowels that were too short. [30] [31] [32]

See also

Related Research Articles

<span class="mw-page-title-main">Wood</span> Fibrous material from trees or other plants

Wood is a structural tissue found in the stems and roots of trees and other woody plants. It is an organic material – a natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or more broadly to include the same type of tissue elsewhere, such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, woodchips, or fiber.

<span class="mw-page-title-main">Lumber</span> Wood that has been processed into beams and planks

Lumber is wood that has been processed into uniform and useful sizes, including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing. Lumber has many uses beyond home building. Lumber is referred to as timber in the United Kingdom, Europe, Australia, and New Zealand, while in other parts of the world the term timber refers specifically to unprocessed wood fiber, such as cut logs or standing trees that have yet to be cut.

<span class="mw-page-title-main">Plywood</span> Manufactured wood panel made from thin sheets of wood veneer

Plywood is a composite material manufactured from thin layers, or "plies", of wood veneer that are glued together with adjacent layers, having both glued with each other at right angle or at 90 degrees angle. It is an engineered wood from the family of manufactured boards, which include medium-density fibreboard (MDF), oriented strand board (OSB), and particle board.

<span class="mw-page-title-main">Joinery</span> Where pieces of wood are fixed together in an assembly

Joinery is a part of woodworking that involves joining pieces of wood, engineered lumber, or synthetic substitutes, to produce more complex items. Some woodworking joints employ mechanical fasteners, bindings, or adhesives, while others use only wood elements.

<span class="mw-page-title-main">Engineered wood</span> Range of derivative wood products engineered for uniform and predictable structural performance

Engineered wood, also called mass timber, composite wood, human-made wood, or manufactured board, includes a range of derivative wood products which are manufactured by binding or fixing the strands, particles, fibres, or veneers or boards of wood, together with adhesives, or other methods of fixation to form composite material. The panels vary in size but can range upwards of 64 by 8 feet and in the case of cross-laminated timber (CLT) can be of any thickness from a few inches to 16 inches (410 mm) or more. These products are engineered to precise design specifications, which are tested to meet national or international standards and provide uniformity and predictability in their structural performance. Engineered wood products are used in a variety of applications, from home construction to commercial buildings to industrial products. The products can be used for joists and beams that replace steel in many building projects. The term mass timber describes a group of building materials that can replace concrete assemblies.

<span class="mw-page-title-main">Structural insulated panel</span>

A structural insulated panel, or structural insulating panel, (SIP), is a form of sandwich panel used in the construction industry.

This page is a list of construction topics.

<span class="mw-page-title-main">Laminated veneer lumber</span> Engineered Wood Product used in wood frame construction

Laminated veneer lumber (LVL) is an engineered wood product that uses multiple layers of thin wood assembled with adhesives. It is typically used for headers, beams, rimboard, and edge-forming material. LVL offers several advantages over typical milled lumber: Made in a factory under controlled specifications, it is stronger, straighter, and more uniform. Due to its composite nature, it is much less likely than conventional lumber to warp, twist, bow, or shrink. LVL is a type of structural composite lumber, comparable to glued laminated timber (glulam) but with a higher allowable stress. A high performance more sustainable alternative to lumber, Laminated Veneer Lumber (LVL) beams, headers and columns are used in structural applications to carry heavy loads with minimum weight.

<span class="mw-page-title-main">Falsework</span> Temporary structure to support permanent structure during construction

Falsework consists of temporary structures used in construction to support a permanent structure until its construction is sufficiently advanced to support itself. For arches, this is specifically called centering. Falsework includes temporary support structures for formwork used to mold concrete in the construction of buildings, bridges, and elevated roadways.

<span class="mw-page-title-main">Formwork</span> Molds for cast

Formwork is molds into which concrete or similar materials are either precast or cast-in-place. In the context of concrete construction, the falsework supports the shuttering molds. In specialty applications formwork may be permanently incorporated into the final structure, adding insulation or helping reinforce the finished structure.

<span class="mw-page-title-main">Structural steel</span> Type of steel used in construction

Structural steel is a category of steel used for making construction materials in a variety of shapes. Many structural steel shapes take the form of an elongated beam having a profile of a specific cross section. Structural steel shapes, sizes, chemical composition, mechanical properties such as strengths, storage practices, etc., are regulated by standards in most industrialized countries.

<span class="mw-page-title-main">Flitch beam</span>

A flitch beam is a compound beam used in the construction of houses, decks, and other primarily wood-frame structures. Typically, the flitch beam is made up of a vertical steel plate sandwiched between two wood beams, the three layers being held together with bolts. In that common form it is sometimes referenced as a steel flitch beam. Further alternating layers of wood and steel can be used to produce an even stronger beam. The metal plates within the beam are known as flitch plates.[1] Flitch beams were used as a cost-effective way to strengthen long-span wooden beams, and have been largely supplanted by more recent technology.

<span class="mw-page-title-main">Cross-laminated timber</span> Wood panel product made from solid-sawn lumber

Cross-laminated timber (CLT) is a subcategory of engineered wood with panel product made from gluing together at least three layers of solid-sawn lumber. Each layer of boards is usually oriented perpendicular to adjacent layers and glued on the wide faces of each board, usually in a symmetric way so that the outer layers have the same orientation. An odd number of layers is most common, but there are configurations with even numbers as well. Regular timber is an anisotropic material, meaning that the physical properties change depending on the direction at which the force is applied. By gluing layers of wood at right angles, the panel is able to achieve better structural rigidity in both directions. It is similar to plywood but with distinctively thicker laminations.

<span class="mw-page-title-main">I-joist</span>

An engineered wood joist, more commonly known as an I-joist, is a product designed to eliminate problems that occur with conventional wood joists. Invented in 1969, the I-joist is an engineered wood product that has great strength in relation to its size and weight. The biggest notable difference from dimensional lumber is that the I-joist carries heavy loads with less lumber than a dimensional solid wood joist. As of 2005, approximately 50% of all wood light framed floors used I-joists. I-joists were designed to help eliminate typical problems that come with using solid lumber as joists.

<span class="mw-page-title-main">Plyscraper</span> Skyscraper made at least partly of wood

A plyscraper, or timber tower is a skyscraper made of wood. They may alternatively be known as mass timber buildings.

<span class="mw-page-title-main">Carbon12</span> Mixed-use in Oregon, United States

Carbon12 is a wooden building in Portland, Oregon's Eliot neighborhood, in the United States. The eight-story structure built with Oregon-made cross-laminated timber (CLT) became the tallest wood building in the United States upon its completion.

Pres-Lam is a method of mass engineered timber construction that uses high strength unbonded steel cables or bars to create connections between timber beams and columns or columns and walls and their foundations. As a prestressed structure the steel cables clamp members together creating connections which are stronger and more compact than traditional timber fastening systems. In earthquake zones, the steel cables can be coupled with internal or external steel reinforcing which provide additional strength and energy dissipation creating a damage avoiding structural system.

<span class="mw-page-title-main">Gothic-arch barn</span> Type of barn with curved rafters

A Gothic-arched roof barn or Gothic-arch barn or Gothic barn or rainbow arch is a barn whose profile is in the ogival shape of a Gothic arch. These became economically feasible when arch members could be formed by a lamination process. The distinctive roofline features a center peak as in a gable roof, but with symmetrical curved rafters instead of straight ones. The roof could extend to the ground making the roof and walls a complete arch, or be built as an arched roof on top of traditionally framed walls.

Brock Commons Tallwood House is an 18-storey student residence at the Point Grey Campus of the University of British Columbia (UBC) in Canada. At the time it was opened, it was the tallest mass timber structure in the world.

Shane Homes YMCA at Rocky Ridge, designed by GEC Architecture for the city of Calgary, Alberta, Canada is a large recreational facility located at Rocky Ridge, Calgary. The main sponsor of the project, Shane Homes, is a large homebuilder company rooted in Calgary. The investment for this recreational center totaled $192 million. The design objective was to introduce a multipurpose health facility to bring both the rural and urban populations in Calgary together through a space that promotes healthy living and community. Shane Homes YMCA opened to the public in 2018 as the construction was fully completed in 2017. This particular YMCA is known as the World's largest YMCA in terms of square footage (284,000 sq ft [26,400 m2]) and contains North America's largest glue-laminated timber roof. This communal facility is home to a multitude of active spaces that provide all ages and abilities with an area that promotes healthy living.

References

  1. Smith and Wallwork. "Faculty of Education". Archived from the original on 27 April 2016. Retrieved 19 April 2016.
  2. Booth, L.G. (1994). "Henry Fuller's Glued Laminated Timber Roof for Rusholme Road Congregational Sunday School and other early Timber Roofs". Construction History. 10: 29–45. JSTOR   41613729.
  3. Rhude, Andreas Jordahl (January 1996). "Structural glued laminated timber: History of its origins and early development". Forest Products Journal. 46 (1): 15–22. ProQuest   214631336.
  4. "History of APA, Plywood, and Engineered Wood". www.apawood.org. Retrieved 12 December 2022.
  5. Sean How, S., Shing Sik, H. and Khairun Anwar Uyup, M. (2016). An Overview of Manufacturing Process of Glued-Laminated Timber. [online] Available at: https://www.researchgate.net/publication/306401137_An_Overview_of_Manufacturing_Process_of_Glued-Laminated_Timber.
  6. Engineered Wood Products Manufacturing. (2002). In: AP-42: Compilation of Air Emissions Factors. [online] Environmental Protection Agency. Available at: https://www3.epa.gov/ttnchie1/ap42/ch10/final/c10s09.pdf.
  7. Simone, Jeska (2015). Emergent timber technologies: materials, structures, engineering, projects. Pascha, Khaled Saleh,, Hascher, Rainer, 1950-. Basel. p. 40. ISBN   9783038215028. OCLC   903276880.{{cite book}}: CS1 maint: location missing publisher (link)
  8. Jeska 2015, p. 41.
  9. Jeska 2015, p. 46.
  10. "APA Publication Search - APA – The Engineered Wood Association". www.apawood.org. Retrieved 13 December 2022.
  11. 1 2 Abed, Joseph; Rayburg, Scott; Rodwell, John; Neave, Melissa (January 2022). "A Review of the Performance and Benefits of Mass Timber as an Alternative to Concrete and Steel for Improving the Sustainability of Structures". Sustainability. 14 (9): 5570. doi: 10.3390/su14095570 . ISSN   2071-1050.
  12. Ong, C. B. (1 January 2015), Ansell, Martin P. (ed.), "7 - Glue-laminated timber (Glulam)", Wood Composites, Woodhead Publishing, pp. 123–140, doi:10.1016/B978-1-78242-454-3.00007-X, ISBN   978-1-78242-454-3 , retrieved 13 December 2022
  13. 1 2 3 Hassan, O.A.B. and Johansson, C. (2018). "Glued laminated timber and steel beams". Journal of Engineering, Design and Technology, 16(3), pp.398–417. doi : 10.1108/jedt-12-2017-0130.
  14. Timber Engineering Europe Ltd. Glulam beams. Timberengineeringeurope.com. Retrieved on 27 September 2015.
  15. 1 2 3 Hassan, Osama A. B.; A.a., Nour Emad; Abdulahad, Gabriel (1 June 2022). "A comparative study between glulam and concrete columns in view of design, economy and environment". Case Studies in Construction Materials. 16: e00966. doi: 10.1016/j.cscm.2022.e00966 . ISSN   2214-5095. S2CID   247065579 .
  16. Harris, Mark (October 2012). "Wood goes high-rise". Engineering & Technology. 7 (9): 43–45. doi:10.1049/et.2012.0902. ISSN   1750-9637.[ dead link ]
  17. Quesada, H.; Adhikari, S.; Smith, R. (2022). "Glue-Laminated Timber" (PDF). Virginia Cooperative Extension. Archived (PDF) from the original on 18 January 2024.
  18. Uwizeyimana, P., Perrin, M. and Eyma, F. (2022). "Assessment of glulam structures: moisture monitoring and investigation on the effect of climatic conditions on durability". doi : 10.24451/2xwb-rt40.
  19. Ayanleye, Samuel; Udele, Kenneth; Nasir, Vahid; Zhang, Xuefeng; Militz, Holger (April 2022). "Durability and protection of mass timber structures: A review". Journal of Building Engineering. 46: 103731. doi: 10.1016/j.jobe.2021.103731 . ISSN   2352-7102. S2CID   244563808.
  20. Naturally:wood Richmond Olympic Oval. Imagelibrary.bcfii.ca. Retrieved on 27 September 2015.
  21. Disney ICE - the warmth of wood heats up an Anaheim ice rink (pdf). APA - The Engineered Wood Association. 2002.
  22. Case Study: Cathedral of Christ The Light - The Ultimate Engineering Challenge (PDF). APA - The Engineered Wood Association. 2008.
  23. Elbein, Saul (13 January 2020). "Will the skyscrapers of the future be made out of wood?". National Geographic. Archived from the original on 17 February 2021. Retrieved 20 February 2021.
  24. Carpentier, Stéphane (24 January 2021). "Notre-Dame de Paris : la restauration de la Cathédrale" (in French). RTL.
  25. Mjøstårnet: World's Tallest Timber Building, Adrian Welch, e-architect.co.uk, 18 August 2018
  26. "World's tallest timber building opens". US Forest Service. 29 July 2022. Retrieved 13 December 2022.
  27. "Centre Pompidou Metz". Architectuul. Retrieved 13 December 2022.
  28. 1 2 3 Hansson, M.; Larsen, H. J. (1 October 2005). "Recent failures in glulam structures and their causes". Engineering Failure Analysis. 12 (5): 808–818. doi:10.1016/j.engfailanal.2004.12.020.
  29. Pousette, Anna; et al. "Durable Timber Bridges Final Report and Guidelines" (PDF). RISE. Research Institutes of Sweden. p. 96. Retrieved 16 August 2022.
  30. Legg, Chris; Tingley, Dan (3 May 2019). "Viability of Modern Timber Highway Bridges" (PDF). School of Renewable Natural Resources, Louisiana State University. Retrieved 16 August 2022.
  31. Jessel, Ella (15 August 2022). "Timber bridge in Norway 'built to last 100 years' collapses after a decade". New Civil Engineer .
  32. "Faults were found on the Tretten bridge when it was inspected in 2016 - news Norway". Teknomers English News. 15 August 2022. Retrieved 16 August 2022.