RawLam - extract from the book: Climate - Building Resilience in the Era of Climate Change

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Climate

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innovation technology

materiality circularity

consumption

construction

Contributors Martin Tamke (Associate Professor), Mette Ramsgaard Thomsen (Professor), Tom Svilans (PhD Fellow), Sebastian Gatz (PhD Fellow) Programme CITA (Centre for IT and Architecture) Institute Institute of Architecture and Technology Collaboration Veksebo Savværk

RawLam — Probing Treeto-Timber Workflows

← RawLam Detail.

Increasing the use of wood in construction helps to lower the carbon footprint of buildings and is a first step towards a biobased economy in construction. However, due to the industrial logics of timber production, where every piece of wood needs to live up to set quality standards, up to 70% of input forest material is lost in traditional workflows during the production of timber for buildings, as it is declared low quality or cut or milled away in process.

Our research probes whether computational techniques can create a new link between the highly variant qualities and appearances of the natural grown material of wood in nature and timber construction in buildings, where predictability and performance within set specifications are key. We pursue a holistic approach, which establishes a flow of data between the currently separate areas of processing trees into timber and the use of it as elements in buildings. For this we need to extend the usual top-down design processes in timber architecture with a bottom-up dialogue between existing material qualities and design performance requirements.

Our development combines material and computational systems to acquire data from the tree, a custom design system, which analyses the data and generates specification for the cutting of boards and the lamination of the elements.

DATA ACQUISITION For data acquisition, we investigate Optical and CT-Scan-based techniques to a) reconstruct a three-dimensional representation of the tree and b) to rate the hyper-local material properties of the timber. With the ability to rate the raw timber,

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↑ Timber Sorting. Detail of cutting instructions on board level and sorting of available stock.

Climate

→ Digitized Material.

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Climate it is possible for us to link the material properties to a structural or design model of a glued-laminated timber beam. This allows the matching of local beam requirements with found timber qualities.

DESIGN SYSTEM RawLam consists of three glued-laminated timber beams which are interlocked by a screw-less connection (dovetail joint). The concept is developed in a top-down manner to fulfil functional criteria in an exhibition setup. All parameters on level of geometry, curvature, section and lamella size and the cutting and placement of lamellas in the beams are the result of our computational model. For this we extend our technologies for the optimization of glulam design with a method to determine the performance needs in all areas of the beams. We differentiate between requirements based on position in the layer stack, distance to joints (for milling details) and overall curvature. The weighting of the requirements is informed by a structural model, fabrication limitations and material requirements for detailing of joints.

DESIGN NEGOTIATION AND PRODUCTION The resulting overall requirements of the layers in the beam assembly are linked to the Douglas fir log and its inherent material qualities.

Within this available material ‘stock’, the desired performative and visual properties are then found by means of a scalable ‘best-fit negotiation’ algorithm. We use multi-objective cutting optimization strategies for each raw board from the source log, find the best match between a list of needed lamella lengths with associated strength requirements and a list of available wood lengths and properties and specify digitally cutting and lamination of lamellae.

FUTURE TREE-TO-PRODUCT WORKFLOWS Although RawLam focuses on the steps from the felled tree to the design of a glued-laminated timber beam, it demonstrates the potential of wood to product workflows, which could in a future connect data from living trees in the forest with design and making of our environment. We gain a product that is hyper-optimized in terms of material usage and novel in its visual appearance. We find as well that more material of the tree was used than would have been the case without our data link. We avoided waste and could produce high-quality elements from lower-quality wood.

↑ Raw Material. The sawn Douglas Fir log from the sawmill. ← Making Detail. ↓ The laminated blanks.

→ RawLam Prototype. RawLam uses low-quality wood, such as boards with wane or bark, in areas with low-performance demands.

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RawLam