Timber Design Society 2021 Series

Timber Design Society 2021 Series 1
Reinforcement of Timber Members
Presented by Daniel Moroder, 8th April 2021

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Current advances in timber engineer are mostly due to the large availability of mass timber products and modern fastener systems. In addition to these, reinforcement of timber members around disturbed areas like notches, penetrations or complex member connections is allowing designers to push the limitations of timber.

These limitations, like low tensile and compression strength perpendicular to grain, can be overcome with the use of reinforcement like screws, rods or glued wooden panels. These measures can ensure an adequate and robust load path in complex timber designs, similar to rebars in concrete.

This webinar revisits basic timber properties to justify the need of reinforcement and provides an overview of typical design situations where additional design checks and potential reinforcement might be required. Different solutions will be discussed including their advantages and disadvantages. The presentation is based on the NZ Wood Guideline Chapter 12.6 ‘Reinforcement of Timber Members’ and will also include the derivations of some of the recommendations. Typical design situations with notches, joints loaded perpendicular to grain, penetrations, bearing reinforcement, shear reinforcement, moment resisting connections and joints with multiple fasteners will be discussed.

Timber Design Society 2021 Series 2
Fire Engineering for Timber Structures
Presented by Dr Andy Buchanan, 6th May 2021

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The topic of most interest to architects is the group number system for exposed wood surfaces, as influenced by the effect of automatic fire sprinkler systems.

The main part of the webinar will cover structural design for fire safety in timber buildings, with reference to the new standard AS/NZS 1720.4. This will include an introduction to fire resistance testing as the basis for structural fire design of light timber framing and mass timber structural members. The webinar will also include charring rates of protected and unprotected wood products, wood properties at elevated temperatures, and fire design of connections. The seminar will be based on the NZ Wood Design Guide for Fire Safety

Timber Design Society 2021 Series 3
Timber Connections with Engineered Wood Screws
Presented by Justin Brown, 3rd June 2021

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This webinar provides an overview of engineered wood screws properties, applications in timber connections, and considerations for design.

Engineered wood screws have distinct differences to traditional wood screws and coach screws which are currently referenced in the NZS 3603 Timber Structures Standard. Their high yield strength, thread pitch and length (for some application over the full length), and large range of diameters, lengths, and head types provide many advantages. The webinar will present state-of-the-art design considerations for Engineered wood screws based on recent research.

Timber Design Society 2021 Series 4
An introduction of mass timber post and beam construction
Presented by Lisa Oliver, 1st July 2021

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Post and beam construction refers to a system where a buildings’ vertical support is built of beams and columns. Compared to conventional light timber framing, timber post and beam construction replaces the need for load bearing walls, allowing for large open spaces. This webinar will highlight the benefits and flexibility of mass timber post and beam construction. You will be introduced to what is possible, some key design drivers and where to find more detailed design information.

Lisa Oliver is a Project Director with Holmes Consulting LP and vice president of the Timber Design Society. She is a Chartered Professional Engineer and has a master’s degree from the University of Canterbury. Lisa has a broad range of structural design and assessment experience in New Zealand and in the Netherlands. Lisa’s design experience with timber includes designing projects such as the MOTAT Aviation Display Hall. She recently co-authored the NZWood Design Guide, Post and Beam Timber Construction. Currently based in Christchurch, Lisa is involved in the sustainability and timber aspects across many projects.

Timber Design Society 2021 Series 5
A Kiwi in Canada: Mass timber case studies and timber design learnings
Presented by Andrew Dunbar, 12th August 2021

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North America is quickly becoming an innovation hub for the implementation of mass timber structures. This is helped by an abundant source of an excellent natural resource (trees) and a supporting industry turning that resource into a material perfect for the building environment.

This presentation is based on experience while working in Canada at Fast + Epp, a firm recognised internationally for their work with mass timber. The presentation will cover general observations of the differences between the New Zealand and Canadian mass timber industries along with case studies of two mass timber buildings – the new 4-storey Fast + Epp office featuring “kiwi” seismic resilience technology, and a 10-storey structure with a full timber lateral system.

Andrew Dunbar is a senior structural engineer at Structex based predominantly in Christchurch. Andrew originally joined Structex as a graduate engineer following the completion of his master’s degree at the University of Canterbury with a focus on mutli-storey timber structures. Andrew is particularly passionate about timber structures, and in 2019, returned to Structex after a 2-year sabbatical in Vancouver, Canada, working at Fast + Epp – renowned for pushing the boundaries of mass timber. In Vancouver, he furthered his expertise in mass timber structures and was involved in several large projects and has returned to New Zealand to continue the push towards mass timber in the NZ context.

Timber Design Society 2021 Series 6
Mass timber structures: The role of resilient connections
Presented by Dr. Ashkan Hashemi, 2nd September 2021

There is an increasing public interest in seismic-resistant structures made with massive wooden panels such as Cross Laminated Timber (CLT). It is well-known that the type and behaviour of the connections govern the overall seismic performance of the building. Thus, special attention must be paid to the connections when designing such buildings. It has been demonstrated that although mass timber structures with conventional seismic detailing could survive the design level earthquakes, the extent of damage in the connectors could be severe. Therefore, it is necessary to have resilient connection systems if a low damage performance is desired.

This webinar provides concepts and case studies of low damage mass timber structures where resilient connections are used instead of conventional high damage/pinching connectors to firstly, introduce energy dissipation to the structures (without damage), and secondly, provide a self-centering behavior. The design approach, design challenges and different aspects of construction are discussed. Furthermore, the significant advantages of low damage mass timber buildings over conventional buildings are discussed. This webinar highlights a great potential for low damage mass timber structures in high seismicity areas.

Timber Design Society 2021 Series 7
Timber connections – the European Yield Model explained
Presented by Pierre Quenneville, 7th October 2021

The webinar will cover the basics of the EYM and its limitations, the load-displacement behaviour expected of the joints and some intricacies and possibilities for timber joint designs. Examples of joints using timber only or timber with steel will be provided. It will not cover the issue of brittle failures.

Timber connections normally consist of metal fasteners that transfer shear loads through a combination of wood bearing and fastener yielding. The design method developed in Europe in the late 1940’s and identified as the European Yield Model (EYM) is very well suited to determine the behaviour and capacity of the connection for a range of timber densities and thicknesses, fastener diameter and stiffnesses. However, some basic understanding of the assumptions is needed to make sure that the theory applies for the problem to be solved.

Timber Design Society 2021 Series 8
Corrosion of Fastener in Timber
Presented by Zhengwei Li, 4th November 2021

This presentation outlines the current scheme and solutions used to specify fasteners to minimise corrosion risks in timber structures and to comply with the New Zealand Building Code clauses B2 Durability. 

Timber-framed buildings retain their prime importance in New Zealand’s residential construction systems where metallic fastenings and fixings such as bolts, brackets, nails and screws play an indispensable role. Metals are not naturally compatible with timbers, and will corrode when timber-metal structures are exposed to adverse environmental conditions, this being contributing to pre-mature material failures, structural damage and building performance degradation.

Timber Design Society 2021 Series 9
Design of light timber-framed bracing walls
Presented by Wouter van Beerschoten, 18th November 2021

This presentation explains different compliance pathways applicable to light timber-framed (LTF) braced structures. It highlights some of the background and assumptions of NZS3604 bracing design based on P21-tested systems. Furthermore, it provides an in-depth overview of the P21 testing protocol and raises awareness of crucial aspects which designers should be aware off when using these values in designs outside the scope of NZS3604. Lastly, it provides some useful data for specific engineering design of LTF bracing walls, as well as several examples of good and not so good designs.