Trends in timber engineering

By - , Build 157

BRANZ Structural Engineer David Carradine reports on the 14th World Conference on Timber Engineering (WCTE) held in Vienna, Austria, in August.

Mock-up of glulam arch frames, made in Austria as an example of prefabrication methods being used.
Mock-up of glulam arch frames, made in Austria as an example of prefabrication methods being used.

WHILE THERE is not a large quantity of timber to be seen in Vienna, Austria has a deep tradition of timber construction, and more than 50% of its land area is covered in forest. It is currently the world’s largest supplier of cross-laminated timber (CLT) panels.

Key topics

As a BRANZ delegate at the conference, I was able to soak up what is happening around the world in the design, analysis, construction and innovation of modern timber buildings.

The conference had some clear trends in the topics covered in papers, posters and keynote and plenary session presentations. They included:

  • integration across research and design disciplines
  • prefabrication of building components
  • large timber buildings.

Integrating primary product research

One early discussion was about integrating timber building development with further research on the primary properties of timber, including influences around growing, selecting and harvesting trees.

Linkages between forestry, timber processing, post-processing, design and performance, including durability, were presented as a way to develop buildings where the base material is engineered from the beginning of the life of the tree.

This notion is also a means of integrating work by researchers, engineers, producers, architects and builders to be mutually beneficial to all involved in developing contemporary timber structures.

Prefab growth driven by CLT

Prefabrication was an underlying theme, driven by the proliferation of cross-laminated timber (CLT) research and development, which has been a major focus at the WCTE for several years.

CLT has moved away from being a uniquely European product. It is now a worldwide construction option gaining popularity in regions where timber is widely used and where improved performance of timber buildings is required. CLT plants have opened in North America and Australasia, and there will soon be one or more in Japan.

CLT’s appeal is strongly tied to its ability to enable a high level of prefabrication – a significant portion of a building can be created in a factory, minimising time and effort on sites.

There have also been improvements in processing mechanisation allowing for very complex structures to be created using timber components – CLT and others. This has opened up a huge market for architects wanting to create a range of building forms that would have previously been impossible using timber.

Timber buildings up to 20 storeys

At the WCTE in 2014, there was a significant focus on larger timber buildings with discussions on many potential projects around the world. The 2016 WCTE took this to the next level with examples of completed and under-construction timber buildings that were previously only concepts.

Timber is no longer only considered suitable for low-rise and mid-rise buildings, and is being implemented in increasingly larger buildings. In British Columbia, Canada, the largest timber hybrid building in the world is under construction, with a completion date of 2019 anticipated.

The Brock Commons building is 18 storeys of student accommodation for the University of British Columbia in Vancouver. It utilises two concrete cores for lateral load resistance with CLT floor plates supported by glue-laminated columns. Numerous papers were presented on the development, design and construction of the building, and time-lapse imagery showed the unprecedented speed with which the building has come together.

The Treet Building in Norway, a completed 14-storey apartment building, currently holds the record for the tallest timber building. It consists of prefabricated modules supported by a glue-laminated structure.

Both buildings were discussed at the conference, and many other projects are in design and construction stages around the world, including a 20-storey building in Austria.

Clearly the move towards bigger timber structures is underway, and at the conference, there was a sense of competition around who would be building the next and biggest timber structure!

NZ post-tensioned systems in the mix

The post-tensioned timber systems developed in New Zealand are increasingly being considered for taller timber buildings as well. The design of a 15-storey building with rocking post-tensioned walls was presented as an option for a building in Ottawa, Canada.

Shake table testing is currently in the development stages for a 10-storey building using rocking CLT walls. This will be a collaborative effort between researchers worldwide, conducted at the University of California, San Diego.

CLT use in New Zealand

While New Zealand may not be racing to construct the biggest timber building on the planet, all the resources are available here to develop innovative timber structures and incorporate global knowledge.

The use of CLT is expanding, with buildings in Christchurch and Kaikoura providing examples of how the technology can be implemented given our seismic risk. Manufacturing capabilities, including computer numerical controlled (CNC) timber fabrication are on the rise, providing more opportunities for accurate prefabrication of timber components and increasingly complex timber designs.

There is a push in New Zealand to make more use of locally grown timber for added-value products like CLT, glue-laminated timber and laminated veneer lumber.

Numerous examples at the conference showed how these products and prefabricated timber systems are being used to push the limits of what can be done with wood.

For more

Visit wcte2016.conf.tuwien.ac.at. A copy of the proceedings is also available from the BRANZ Library.

Download the PDF

More articles about these topics

Articles are correct at the time of publication but may have since become outdated.

Mock-up of glulam arch frames, made in Austria as an example of prefabrication methods being used.
Mock-up of glulam arch frames, made in Austria as an example of prefabrication methods being used.

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