A cyclical assembly and disassembly of non-standard timber structures with timber joints
1Royal Danish Academy, Denmark Copenhagen Centre for Information Technology and Architecture (CITA) 2022
Choo Ee Pin1
Tutored by: Tom Svilans1
1. Background
(1)The practice of building permanent structures only to tear them down when it no longer meets the demands of society is a huge drain on our natural resources
(2)Construction sector produces 37% share of global CO2 emissions This mainly comes from the manufacturing of steel and concrete (UNEP 2021).
How can we challenge the existing paradigm of a building’s life cycle?
Design for Disassembly (DfD) responds to the growing weight of embodied energy in the materials and the sequential renovation cycles over the building’s lifetime (Crowther 2009). This thesis will explore these cyclic processes of timber structures with timber joints at the scale of materials, components, and structure.
What are the challenges of disassembling timber structures?
1. Background
Wood is an anisotropic material that shrinks and expands nonuniformly due to changes in moisture content, and these changes need to be accounted for during the design (Rogeau et al., 2020). Any misalignment could lead to improper connection and separation.
How can digitalisation and automation aid in these cyclical processes?
As the construction industries move towards digitalisation and automation (Construction 4.0), automation could potentially increase productivity in construction (Sawhney et al., 2020). Digitalisation offer opportunities to enable DfD through adaptive work flows and managing complexities in disassemblable timber structures.
2. Architectural intention
1. Use modular designs
2.Provide realistic tolerances to allow for manoeuvring during disassembly
1972 - Nakagin Capsule Tower
2. Architectural intention
3. Use mechanical connections rather than chemical ones
4. Design joints and connectors to withstand repeated use
2. Architectural intention
5. Make materials and components of a size that suits the intended means of handling
6. Use construction technologies compatible with standard building practice and common tools
Tsugite: Interactive Design and Fabrication of Wood Joints
How can [adaptive digital processes] [prolong the life cycle] of timber structures through designing for [multiple stages of reconfiguration]?
4.1. Research scope
Right: Architectural intervention that enables materials to stay within the system through multiple layers of reuse before finally being removed when it is no longer viable.
Left: A flow chart showing a conventional life cycle of timber from extraction to a recycling plant or a landfill.
(1) Digitalisation
(2) Reconfiguration
5. Automation and digitalisation
The diagram illustrates the complexity of buildings being assembled and disassembled over the same period of time (Smith, R. E.,2010). Automation through tracking larger amount of parts could provide a possible solution to organise these elements and allocate them appropriately based on their functions.
5.1. Digitalisation and tracking
Timber frames are disassembled into individual elements. Each element is then scanned processed and updated in the database for the next cycle.
5.1. Digitalisation and tracking
Using the unique grain pattern and geometric shape as key features it is possible identify individual elements and its orientation.
Test image (Incomming)
Original image (Data base)
5.1. Digitalisation and tracking
Using the unique grain pattern and geometric shape as key features it is possible identify individual elements and its orientation.
Test image (Incomming)
Original image (Data base)
5.2. Digitalisation and tracking
Computer vision
5.2. Markings
Computer vision
- Identification - Instruction
5.2. Markings
Computer vision
- Identification
- Instruction
5.2. Markings
Computer vision
- Identification - Instruction
5.1. Digitalisation and tracking
5.1. Digitalisation and tracking
*Typical oven-dry shrinkage values for medium density woods ** At the range of 8-15% moisture content. The shrinkage will then be only a half to three-quarters of the oven-dry shrinkage value - Walker and Walker 2006
6. Multi phase elements
Above: Mapping of joint roles changing over multiple cycles of reconfiguration and re-machining with new functions.
Compression
Degraded None Finishing Tension
(a) Additive
(b) Subtractive
6.2.1. Re-machining
n
n
6.3. Aggregation of parts
7. Case study / Speculation
7. Case study / Speculation
7. Case study / Speculation
Overlay of contours and building foot print from 2021 to 2061.
7. Case study / Speculation
University of Stuttgart - flexible robotic timber construction platform, TIM,
9. Conclusion
How can [adaptive digital processes] [prolong the life cycle] of timber structures through designing for [multiple stages of reconfiguration]?
[adaptive digital processes] [prolong the life cycle]
[multiple stages of reconfiguration]
This thesis explores these cyclic processes of timber structures at the scale of materials, components and structures. It establishes a potential solution for extending the life cycle of buildings by giving timber elements multiple functions over time. This thesis also highlights and overcome some of the challenges of designing for disassembly with adaptive digital processes through the use of digital tools and current build technologies.
10. Limitations and further studies
Limitations:
(1) While this thesis only explored the use of a 3 axis CNC machine, this method can be expanded to use more advanced tools. This would enable the fabrication of more intricate joints and non planar elements.
(2) Although this thesis focuses only the timber frame structure, designing architecture that can be disassembled involves planning for all components used during construction.
(3) The joints designed in this thesis are designed through the iterative process of the physical prototypes. When applied to a larger scale, proper structural analysis needs to be done in order to determine the specifications of the joints needed.
Further studies:
(1) Further studies can explore the use of different types wood for specific functions. This could potentially increase the longevity of each joint. However extra care needs to be taken when gluing hard and soft wood.
(2) Deeper material behavior understanding of how the joints degrade over time. Being able to predict the decay of elements would help with both the designing of parts and maximizing its potential life span.
(3) Further studies could evaluate how many times an element is re-machined before the energy cost out weighs producing a new component.
