Work Packages

We are organized in 4 interdisciplinary working groups to achieve our goals in the field of multi-storey timber building design fields:

  1. Working group 1: Design for adaption, reuse and repair
  2. Working group 2: Deformations and vibrations
  3. Working group 3: Accidental load situations
  4. Working group 4: Sustainability and durability

WG 1 – Design for adaption, reuse and repair

This WG will revolve around the planning and design of buildings to be more sustainable and reliable from the very beginning of the process. A holistic approach is chosen in order to consider the demands and benefits of all stakeholders in the building design process. We want tall timber buildings of the future to fulfill not only the basic design code requirements, regardless if national or international, but also be prepared for potential future changing demands and requirements. Hence, they would serve as lighthouses of future construction in general. This shall be achieved by considering robustness and approaching the adaption, repair and reuse of the building and its components in a cross-sectional strategy considering the various stakeholder interests. If structures are not design keeping Robustness in mind, the collapse of a single element can trigger further disproportional consequences, possibly even leading to full collapse of a structure. In taller timber buildings the concept is still not well understood, yet it is recognized as crucial due to complex timber properties and assembly procedures. As such it needs to be analysed more in depth and become a part of standard taller timber building design of course in a holistic manner, considering several other boundary conditions and consequences.

Adaption is the process of considering the demands and needs of the prospective users in the actual usage of a product. This concept is already valid for other products, such as smartphones, cars, clothes etc. The users of the building can adopt the building to their demands, both in a short-term perspective or for long term use, including the adaptation of both load-bearing and non-load-bearing elements. This also includes extensions of the structure (topping up, etc.) and provides higher benefits for the owner.

Repair will implement the possibility that damaged load-bearing components meaning that parts of the structure can be easily restored or exchanged, which allows to react to unforeseen and accidental cases of e.g. water leakage, compartment fire, etc. Timber buildings are often seen to be potentially more prone to damage compared to other building materials. Concerns are related to wood degradation due to water damage or insect attack but also to fire damage or damages after earthquakes. Replacing load-bearing elements is already a challenge in smaller buildings and is even a greater for taller ones. Redundancy is only a part of the answer, solutions need to be sought through a wider audience. The possibility to repair will increase the trust in timber as a reliable and high-quality building material and increase and maintain value of the building.

Reuse is obligatory in the light of long-term sustainability, carbon storage, recycling, and circular economy. After reaching the end of the service life, which is often planned to be after at least 50 years, the building can be deconstructed and parts can be reused, recycled or rearranged and can be fed back to the value chain. The approach to design for adoption, reuse and repair introduces the concept of circularity not only to the material and material flow but is a more holistic approach on the structural, building, user, and societal level. By making buildings adaptable to new demands, circumstances or needs to repair, the life cycle of the building can be extended into further cycles. Introducing timber in multi storey buildings is still rare on the market and not necessarily applicable to larger quantities. The challenges described need to be explicitly considered when scaling up the market and not taken for granted.

WG 2 – Deformations and vibrations

WG 2 will focus on the wide topic of deformations and vibrations in taller timber buildings. Timber has inherently low mass and elastic modulus compared to other building materials. For spruce, the respective values are 5- and 3-times lower compared to reinforced concrete. The low mass is generally beneficial as it results in lower forces. Either on foundation that can in term be smaller (less material used, beneficial for the environment) or simpler (foundation plate instead of piles). Or for seismic design where, due to second Newton’s law, the lower accelerated mass generates lower seismic forces, which result in lower damage or possibly even no structural damage at all. However, these same inherent properties of wood present design challenges for taller timber buildings. Firstly, because the more standard spans in certain building typologies, i.e. offices, are optimized to other materials, namely steel and concrete. Merely adopting the same building boundary conditions for timber structures can lead to non-rational design as the load bearing elements need to be thicker due to serviceability demands, namely, keeping the deformation as well as vibration in check. And secondly because mid-rise timber buildings are already tall enough to be affected by wind vibration. In addition to their low mass and stiffness also due to the uncertainties in viscous damping they offer. These properties are also responsible for the low sound isolation timber constructions offer in the lower part of the acoustic spectrum. Consequently, the acoustic demands lead to decoupling of structural elements in order to break the sound vibration transfer. That unfortunately causes problems with both wind as well as seismic design demands where a tightly bonded system is essential.

WP 3 – Accidental load situations

Work in this Work Group would in essence revolve around the main accidental load situations taller (timber) buildings face, namely earthquake and fire. In unfavorable, but not uncommon situations, these events are not independent, but fires follow earthquakes due to ruptured electrical and gas installations. This issue has been given little attention in Europe, however more in the United States but not yet well on taller structures. The issues of earthquake and fire are demanding by themselves. Earthquake design of multi storey timber buildings has only been a topic of (isolated) research for less than 15 years, with the current state of knowledge still low compared to concrete and steel counterparts. Fire design of timber on the other hand can be handled with existing design methods and principles, however the protection demands (protection times) have been raised as taller buildings need to withstand fire longer in order to enable safe evacuation of people. This in term also raises the bar for fire protecting solutions as well as performance of existing products. Namely, CLT made with polyurethane adhesive has displayed delamination problems, unacceptable in taller timber buildings. Combining merely seismic and fire demands is a challenge by itself. However, the fire cladding demands can run into collision with acoustic cladding and these run into conflict with seismic and wind demands. The cladding demands overall are in conflict with the human wellbeing aspects which prefer to have timber exposed.

WG 4 – Sustainability and durability

Timber constructions have gained the (rightful) reputation of being a sustainable building option. On the other hand, they also raise questions regarding their durability. They are more susceptible to damage, either induced by moisture or insects as well as design mistakes due to their complexity. They are also less forgiving when it comes to construction mistakes, possibly leading to premature failure of their building components. This Work Group will look into the issues dealing with taller timber building environmental footprint and their longevity based on the design details, all assessed through the interdisciplinary prism of the consortium’s experts. The results of this Work Group’s work will be in close correlation to WG 1, where the initial design assumptions will be considered. As in other WGs, work in this group will also be country dependent as, apart from local legislation, local climate properties are also of great importance. The possibility to build safely and effectively in areas with heavy rain and snow differs greatly from dryer places. This in term influences the construction technologies, which in term affect the building erection price, which makes the timber alternatives to concrete or steel more or less viable. For Europe that strives for an increase in sustainable timber construction, this opens a discussion on state subsidies for timber construction in order to make them more attractive to investors. The interdisciplinary consortium, also including LCC and S-LCA experts, will also be able to provide answers to such questions.