Lamella by finbarcharleson

LAMELLA Finbar Charleson MArch Unit 14 Thesis

LAMELLA Evolving the timber frame in the age of information

Finbar Charleson Unit 14 MArch Thesis BARC0011 Word Count: 9,812

Bartlett School of Architecture UCL

Acknowledgements Thesis Tutor: Oliver Wilton (Bartlett) Module Directors: Oliver Wilton (Bartlett) Edward Denison (Bartlett) Robin Wilson (Bartlett) PG 14 Tutors: Dirk Krolikowski (DKFS/Bartlett) Jakub Klaska (ZHA/ Bartlett) Structural Engineer: Rasti Bartek (Cundall) B-Made Staff: Niamh Grace Mads Pedersen All Workshop Staff Material Provider: Danzer UK Additional Support: Steven Johnson (Arch Ensemble/Bartlett) Tom Svilans (CITA/Bartlett) James Angel (Danzer UK) Fellow PG14 Students Friends and Family

Material Sponsor:

LAMELLA Evolving the timber frame in the age of information

Finbar Charleson Unit 14 MArch Thesis BARC0011 Word Count: 9,812

Bartlett School of Architecture UCL

Material Sponsor:

Lamella Abstract

This thesis focus is on the scaled physical prototyping of large-span engineered timber frame structures, with the work located in a historical and theoretical context. There are three sections to the thesis, under the headings of Topic, Abstraction and Synthesis. The first section forms the literature review wherein a concise history of timber framing is catalogued and discussed, recording some of the techniques and tools utilised in the production of timber frames in line with Christoph Schindler’s periodisation model defining the history of timber construction through three waves : ‘hand tool technology’, ‘machine tool technology’ and ‘information tool technology’. The second section of the thesis takes Schindler’s third wave as a point of departure, documenting the design and fabrication of a series of scaled structures utilising digital tools for design, analysis and fabrication. The third section draws from the library of techniques developed in the previous section in order to develop a design methodology for the design of a long-span structure within the design studio project, and to develop a two-part scaled prototype of a part of the proposed structural frame.

Fig. 1.1.

Final Prototype Detail (Opposite) Close up view of one of 9 physical prototypes developed in the thesis.

Lamella Structure Lamella

Noun (In Construction) A thin length of timber from which Glulam is constructed.

Noun (In Biology) A thin layer or membrane.

There are three sections to the Thesis under the headings of Topic, Abstraction and Synthesis.

Introduction

Sectionâ&#x20AC;&#x201A;1. Topic: Timber Frame Evolution 1.1. Introduction

1.2.

Wood: A Definition

Composition 12 Growth and Structure 14

1.3. Hand The First Frames The Right Tool for the Job Wooden Ship Evolution Naval Lamination: The Clipper The Church The Barn

1.4. Machine

16 16 17 18 20 24 26

Early Machines 32 2x4 33 Wartime Innovation: Advent of the Mould 34 Domestic Translation: Aalto and Mollino 38 Industrial Integration: Rogers and Hopkins 40 Industrial Refinement: Renzo Piano 42

1.5. Information Finding Form: Frei Otto The Complex Assembly: Thomas Herzog Digital Turn: The 21st Century Research Group

1.6.

Section Conclusion

44 44 46 48

Sectionâ&#x20AC;&#x201A; 2. Abstraction: Lamination Experiments 2.1. Introduction

2.2.

Engineering Timber Processes and Products

2.3.

Lamination Experiments Spliced Lamination Continuous Cruck Lamination Additive Lamination Cross-Laminated Shell Cross-Laminated Surface Seamless Column Cross-Laminated Tube Bifurcating Tube

2.4.

Section Conclusion

56 56 60 64 68 72 76 80 84

Sectionâ&#x20AC;&#x201A; 3. Synthesis: Design Studio Project 3.1. Introduction

3.2.

Project Description

Overview 92

3.3.

Design Development

Structural System 94 On Branching 96 The Fork 98 Designing for Stress 100 Rationalisation 102 Intersection: Material and Analysis 104 Modelling 106 Multiple Storeys: The Market Hall 108 Composition 112

3.4.

Component Frabrication

114

Form Fabrication 114 Pressing 116 Bending 118 Lamination 120 Assembly 122

3.5.

Section Conclusion

124

Conclusion

128

Bibliography

132

List of Figures

134

Appendix: Additional Drawings

139

Thesis Introduction

There is currently widespread interest in timber construction due to the potential for sustainably farmed timber to store atmospheric carbon. The construction industry accounts for 39% of energy-related carbon dioxide (UKGBC, 2015) and so specifiying the renewable material as a primary structure can deliver significant reductions in the global warming potential of the industry (Abergel et al. 2017). Advances in design and manufacture and developments in fixing and lamination have given rise to myriad products of varying applications from primary structure to insulation, utilising all parts of the tree. The material is increasingly placed under new performance constraints, requiring the application of tools for analysis and fabrication, with forms of architecture emerging as a result (Thistleton, 2018). The thesis draws upon Christoph Schindler’s periodisation model to situate the intention to develop a timber frame suited to the age of ‘information tool technology.’ (Schindler, 2007, p. 12). A set of 8 lamination experiments serve to explore the opportunities afforded by digital fabrication and analysis in conjunction with emerging engineered timber products. A series of scale prototypes adopt laser cutting, 3d-printing and CNC milling to generate formwork for laminated timber structures at scale. The final section proposes a long-span laminated timber frame system situated within the studio design project. The section proposes a digital workflow for the design of a system based on stress visualisation using Karamba 3D in order to establish an effective and informed means of material distribution. The thesis looks to propose a viable timber frame for the age of ‘information tool technology’ addressing the need to laminate large numbers of lamella and splice prefabricated components.

Fig. 1.

Moss Covered Tree (Opposite) Chamonix, France.

‘A century after the introduction of modern concrete, engineered timber is following a similar trajectory. Early adopters of the new material mimic the existing architectural forms, but as the new engineering possibilities are developed, a new architecture emerges, which is emblematic not just of the characteristics of the material but of our relationship with our environment’ (Andrew Thistleton, 2018)

Section 1. Topic: Timber Frame Evolution 1.1. Introduction As a literature review, the following section is directed at the chronological developments in timber construction from ‘Hand tool Technology’ to ‘Information tool Technology’, (Schindler, 2007, p. 3). The latter is the point of departure for the proceeding primary research. Timber is a natural choice for building construction based in its natural properties. Heidegger recognises ‘firmness and pliancy’ as the defining characteristics of wood (Heidegger, 1971, p. 46), whilst the high performance in both compression and tension has meant that timber has found many applications from furniture to multi-storey buildings. One does not need to look far to find examples of long-standing structures built from wood. Forested climates across the globe have a rich history of framing with influences from other industries evident in the evolution of the tools, systems and techniques. Frampton suggests that architecture is ‘suspended between human realisation and the maximising thrust of technology’(Frampton, 1995, p. 23). With this notion in mind, we can understand that the timber structures we inhabit should evolve in relationship to the technology available to produce them. The 20th century gave rise to rapid industrialisation, radically shifting the tools and techniques to process timber for construction from the age of ‘hand tool technology’ to the ‘machine-tool’ and ‘the information tool’ (Schindler, 2007, p. 3). These developments in technology ushered in new forms of framing, whilst rapid urban growth created a demand for cost effective, industrially manufactured systems. The history of joinery born from an intimate knowledge of the material evolved in favour of the easily assembled Platform Frames constructed from 2x4 inch sections, thin sheets of ply-wood and nails. The latter 20th century and early 21st century have seen much innovation within the design of the timber frame, whilst new tools for analysis and fabrication provide an opportunity to give complexity and character to the many industrialised products available.

Fig. 1.1.

No. 3 Slip (Opposite) Boatbulding and Repair shelter designed by Master shipwright Sir Robert Seppings and constructed in Chatham Dockyard in 1838.

1.2. Wood: A Definition Composition

‘The Grain of the Wood Told Secrets to Them’ (Sturt, 1923, p. 32)

Wood is a natural composite material made up mainly of cellulose fibres in a structure of lignin (a glue-like chemical substance that binds the cellulose and makes it rigid) (Fig. 1.2)(Reinprecht, 2016, p. 9). A tree increases in size each year by forming a new woody layer between the old wood and the bark. Within this woody layer, water and nutrients are carried up from the roots. Sugars from photosynthesis are carried down from the leaves. Although he predominant orientation of these fibres is that of the direction of growth (Fig. 1.3), fibres composed of medullar ray cells grow in a perpendicular orientation (Fig. 1.6). Each year of growth, the inner layers relinquish their active role in the life of the tree and serve to ensure the width and mass of the trunk and branches are enough to allow for upward growth to gain access to sunlight. As these layers give up their active role in the conducting of water, they become stiffened with lignin and form the ‘heartwood’ (a harder and darker part of the trunk than the outer ‘sapwood’) (Fig. 1.4).

Cellulose

Hemicellulose

Lignin

Molecular Level

Lumen Inner Layer (S3) Middle Layer (S2) Outer Layer (S1) Primary Wall Middle Lamella Fig. 1.2.

Molecular Structure of Wood (Above Right) Cellulose, Hemicellulose and lignin form the basic molecular structure.

Fig. 1.3.

Anatomical Structure of Wood (Right) A section through a single fibre of wood shows the series of walls dividing them.

Fig. 1.4.

Geometric Structure of Wood (Opposite) The trunk of the tree shows variation in density from the pith to the bark.

Anatomical Level

Bark

Phloem

Cambium

Pith

Sapwood

Heartwood

Geometric Level

1.2 Growth and Structure The growth of branches to receive sunlight places demands on the trunk for increasing support, which is in turn being shaped at its base by the distribution of roots searching for water (Fig. 1.8). Annual rings visible in the cross section of the tree indicate the age of the specimen, whilst their thicknesses indicate changes in growing conditions . Among other signs of response (Fig. 1.5), fertile soil will yield wider rings, whilst infertile soil will yield thinner (Bramwell, 1982, p. 12). These characteristics can have impacts on the mechanical properties of the wood through variation in the performance in tension and compression in the Longitudinal, Radial and Tangential directions (Fig. 1.7) (Green et al., 1999, p. 2).

Protective resin layer Slow Growth Drought Fire Damage Fast Growth

Resin Canal

Ray Cells

Fig. 1.5.

Growth Patterns (Top) Reactions to clement or adverse conditions are evident in the physical structure of the log cross section.

Fig. 1.6.

Hardwood Composition (Centre) Microscopic drawings indicate variation in vertical canals and direction from medullar ray cells.

Fig. 1.7.

Timber Coordinate System (Bottom) Varying between species, timber generally withstands the greatest load in the longitudinal axes with very poor performance in tension in either the tangential or radial axes.

Fig. 1.8.

Longitudinal

Ash Sapling Anatomy (Opposite) Varying between species, timber generally withstands the greatest load in the longitudinal axes with very poor performance in tension in either the tangential or radial axes.

Tangential

Radial

Crown

Leader Branch

Lateral Branch

Watersprouts

Secondary Scaffold Branch Main Scaffold Branch

Trunk Suckers

Roots Surface Roots

Taproot 17

1.3. Hand The First Frames Timber construction is the oldest, and was in pre-industrial times, the most economic method of construction. Schindler proposes a three-part periodisation model as a lens to study the evolution of timber construction. The underpinning principle of which is that manufacturing technology is a product of a synthesis between material, energy and information (Schindler, 2011, sec. 1) In the first phase titled the ‘Hand-Tool Technology’ period we can understand that in the production of wooden artefacts muscular strength by man and animals provided the necessary energy for all processing steps whilst, the quality and the speed were dictated by the knowledge of the craftsman. Information had a crucial role to play in the age of hand technology in that the crafts-person would inscribe notes and symbols directly onto the element (Fig. 1.10). These notes were not providing information about dimensions as for the most part, the grain of the wood dictated the profile of the elements used in construction from barns to ships. In this way the information passed on to the material was used to identify the location of the element with respect to others, with the intention to be clear and usable. It is highly likely that these systems of markings are modified according to the personal conception of the given crafts-person. With precision limited by the skill of the human hand within which matter, energy and information converged (Schindler, 2011, sec. 3). In the UK there is a rich history of timber framing to be understood simply through the proliferation of carpenters’ marks. The marks allowed for the transfer of information for the assembly of components. To this day this information transfer is necessary in the design of large buildings due to the limitations of transportation, material sizes and, in the case of many early timber frames, the size of the trees themselves. (Fig. 1.9) shows the four main methods of marking employed by ‘hand technologists’; scratching, chiselling, incising and gouging (Brunskill, 1985, p. 108)

Fig. 1.9.

Traditional methods of marking Primarily as means of identifying elements within a larger assembly, the marks were central to the construction logic of the early barns.

Fig. 1.10. A Carpenter’s Marks in Cruck Barn, UK. Many barns still display their logic of construction through the carpenter’s marks.

Long or Short Chiselled

Curved Chiselled

Scribed Circles

Scribed Half Circles

Single Flag

Double Flag

1.3 The Right Tool for the Job Although timber is a readily workable material, tools are necessary to create building components from its natural state. Very early in the age of ‘hand tool technology’ the wedge (Fig. 1.11) was used in sharpened stones, axes and planing devices (Fig. 1.12) ( in translation of logs to hewn timber. In using the axe, the profile of the element was largely defined by the grain of the piece of wood, as it was split or shaved and the surface from the growth ring could be left undamaged. (Zwerger, 2015, p. 53) With the development of the saw, the run of the fibres was ignored. This meant that waste could be reduced in the compared with the use of the axe, however it became more difficult to ‘allow nature to perform the required part of the structure’(Zwerger, 2015, p. 46). As tools evolve for processing timber, so do the timber construction systems. The design of the saw has not changed significantly since 15th Century Egypt, the modern hand planer embodies many characteristics of those attributed to first century Pompeii and the axe is almost identical to many dated as far back as Rome in 500 BC (Schindler, 2009, p. 98) Many of the tools seen to be cutting edge today have in fact been in development for some time.

Fig. 1.11. 6 Simple Machines. (Above Left) Lever, Inclined Plane, Pulley, Screw, Wheel & Axle and Wedge. Fig. 1.12. Hand Tools. (Left) The Axe, Adze, Hand Plane and Saw were all used in conjunction with measuring devices to cut and carve wood before mechanisation.

1.3 Wooden Ship Evolution Timber was processed in innovative ways in the production of wooden ships. Their construction has given rise to the intelligent assembly of elements born out of a need for formal differentiation according to two main performance criteria; to maximise speed and haulage. Rudimentary canoes and rafts gave rise to the kit-boats of Egypt, constructed from short elements sewn together by ropes in order to last the 750-mile length of the River Nile. Developments in boat building can be traced then from the Aegaean Galley, Roman Triremes, Northern and Southern European Cogs, Carracks, Chinese Junk ships and The Galleon (Fig. 1.13) (Greenhill, 1974, p. 5). A great moment in European boat building tradition was to be the Viking Long-ship. (Fig. 1.14) illustrates the specific locations of the components present in the Oseberg Viking Long-ship and their approximate locations in the tree from which they were extracted. (Bramwell, 1982, p. 50) Although there were trees present which would yield logs for the construction of long-spanning elements, the Vikings felled trees with unusual characteristics for the expressed purpose of applying the inherent structural characteristics. An intriguing dimension to this fact is the way in which the elements were further crafted and tailored to meet not only the structural demands but allow for elegant forms and rich ornamentation (Zwerger, 2015, p. 72).

Khufuâ&#x20AC;&#x2122;s Ship

North Africa 3100 BC

43m

Roman Trireme

Mediterranean

35 - 50m

Cog

1200 BC

Scandinavia/Mediterranean

15 - 25m

1100 AD

Junkship >50m

Manila Galleon 50m

Aegean Galley 30 -40m

Viking Long-ship 37m

The Oseberg Viking Ship. (Opposite) Isometric diagram indicating the location of specific structural elements within the naturally bent members of the tree.

Clipper 70m

Scandinavia 1025 AD

Carrack 45m

Southern Europe 1300 AD

China 1400 AD

Spain 1500 BC

Fig. 1.13. Concise wooden ship evolution. (Right) Influential wooden ships arranged chronologically with overall length from bow to stern and year of emergence. Fig. 1.14.

Greece 1200 BC

England 1800 AD

H F

A B H

1.3 Naval Lamination: The Clipper The English Clipper was an important development in the lamination of timbers to create long-spanning structures. It was one of the last wooden ships to traverse the Indian Ocean before the introduction of composite and metal hulls. It was built to meet demands in speed and haulage, as developments in technology were driven by the need to return home to England from the far east with the first shipment of tea. (MacGregor, 1972) It was the need for strength and speed that gave rise to the complex arrangement of laminated elements within the keel (Fig. 1.17) whilst the requirement for maximum haulage gave rise to the wide hull. It was the assimilation of the two performance criteria of speed and haulage that was addressed with the graceful and undulating hull (Fig. 1.16) (Fig. 1.18). The Clipper applied similar techniques to the Viking Oseberg ship in the sourcing of bent timbers to construct the complex arrangements of laminated elements (Fig. 1.15). The prized timbers would vary between ships in accordance with resources, however certain timbers from the â&#x20AC;&#x2DC;hedgerow oaksâ&#x20AC;&#x2122; were known to be favoured . (Bramwell, 1982, p. 60)

Stern

Main Hull

Bow

Wing Transom

Stern Post

Knee

Bobstay Piece

Outer Chock

Centre Chock

Knighthead

Inner Chock

Lacing Piece

Independant Piece (Cutwater) Keel Apron

Keelson Deadwoods

Gripe

Fig. 1.15. Bent Timbers of the Clipper (Opposite Above) Fig. 1.16. Clipper Assembly (Opposite) Fig. 1.17. Clipper Bow Construction (Above)

Gaff Span

Gaff

Span Signal Halliards

Gaff Detail

Sail Gooseneck Boom Inhall Outhall

Boom Detail

Teak Rail Poop Deck Upper Deck Lower Deck

Keel

Fig. 1.18. Clipper Hull Section & Details 24

Monkey Rail Main Deck Beam Frame Planking Mast Limber Strake Floor Keel False Keel Worm Shoes

Hull Short Section

1.3 The Church The tradition of applying bowed timbers in long-spanning elements can be seen in a number of historic buildings. The structural benefit of their application was in achieving a joint-free transition between roof slope and wall, and hence the direct transmission into the ground of the forces acting on the roof (Zwerger, 2015, p. 50). The Viking craftspeople responsible for the construction of the Long-ships were very likely to be the same who constructed the influential stave churches of Norway and Sweden (Fig. 1.9). There was a direct translation in terms of construction from the complex hull of the Long-ship to the roof structure of the Stave Church visible in a comparison of the main frames of the ship and the quadrant brackets of the church frame (Fig. 1.20) (Lindholm and Roggenkamp, 1969, p. 25)

Fig. 1.19. Technology Transfer from the Viking ship to the stave church. (Right) Roggenkamp proposes that the stave church took direct influence from the boat building techniques used in Viking Longships like the Oserberg. Fig. 1.20. Borgund Stave Church Wormâ&#x20AC;&#x2122; Eye Isometric (Opposite) Colour coded elements carved from naturally bent timbers.

Rafter Primary Quadrant Bracket Secondary Quadrant Bracket Post Bracket

1.3 The Barn Square hewn lengths of timber were well within the range of tools available and because a frame needed fewer such members than a log or plank structure, framing eventually became the pre-eminent method of building in wood (Pascha, 2014, p. 9). The evolution of the frame is widely accepted to have followed a transition from early tent-like structures, to the simple Cruck followed by the post and beam system (Fig. 1.21) (Bramwell, 1982, p. 35). The Cruck frame was constructed from pairs of timbers known as blades. They were of heavy and large cross sections through the trunk of the tree and the bow of a large branch (Fig. 1.22), so their application utilised the natural bend assumed by the tree in growth. Many examples of Cruck frames stand hundreds of years after construction as the form offered better resistance to loads than sawn frames (Zwerger, 2015, p. 50). The evolution of the frame saw the simultaneous increase in overall complexity as the number of connections increased with the number of elements. The Cruck system became increasingly less viable as the demand for timber frames in response to increasing population favoured homogeneous elements, considered to be more versatile and readily put to use. (Zwerger, 2015, p. 43) A complexity developed around the development of the structural system (Fig. 1.25) and the joining methods (Fig. 1.23)(Fig. 1.24). At the same time, however, the inherent complexity of the structure was somewhat diminished as bent timbers were no longer favoured as the primary structure.

Fig. 1.21. Timber Frame Evolution in Britain (Right) Simple tent structure, weighted bent timbers, the Cruck and the bracketed frame.

Fig. 1.22. Typical Cruck Frame System (Opposite) Cruck â&#x20AC;&#x2DC;bladesâ&#x20AC;&#x2122; were hewn from the naturally bent timbers of the oak tree.

Cruck Blade Sole/Wall Plate Wall Post/ Rafter Arch Brace Purlin Collar Beam Collar Tie Stone Foundation

Lap

Half Lap

Stopped Lap

Halved

Secret Double Dovetail Lap

Secret Single Dovetail

Dovetail Lap

Notched Lap

Doubled Cogged

Single Cogged

Halved Joint

Lateral Bevelled Halved

Oblique Tenon

Square Housed

Dovetail Housed

Bevelled House

Free Tenon

Barefaced Tenon

Dovetailed Tenon

Foxtail Wedging

Fig. 1.23. Lap Joints 30

Fished

Bridled

Face Halved

Edge Halved and Tabled

Edge Halved, Tabled and Keyed

Face Halved

Face Halved with Blade Abutments

Splayed, Tabled and Keyed

Splayed, Tabled and Key Included

Over-squinted Abutments

Splayed with Sallied Vertical Abutments

Splayed with Square undersquinted abutments

Splayed with square vertical abutments

Scissor Joint (For Vertical Use)

Splayed with Bridled Abutments

Splayed, counter tongued and grooved

Sallied and Bridled Abutments

Under-squinted Abutments

Bridled Abutments

Edge Halved, Tabled and Wedged

Fig. 1.24. Splice Joints 31

Harmondsworth, London

Headstone, Harrow

Littlebourne, Cantebury

Passenham Manor, Milton Keynes

Ashleworth, Gloucestershire

Gunthwaite Farm, Sheffield

Swalcliffe, Oxfordshire

Bredon, Gloucestershire

Lacock, Wiltshire

Pilton Grange, Somerset

Bradford on Avon, Wiltshire

Frocester Court, Gloucestershire

Ridge Purlin

Collar Tie Beam Cruck Blades Side Purlin Common Rafter Entrance

Buttress Slot Window

Fig. 1.25. Barns of the UK 32

Causeway Farm

Hall Farm

Pendle

Gunthwaite Farm

Rivington

Oaks Fold

Arley

Unthank

Tatton Park

Barlow Woodseats

Cholstrey Court

Swalcliffe

Upper Heyford

Noteley

1.4. Machine Early Machines Woodwork was the only traditional building craft to experience the full force of the industrial revolution during the nineteenth century in Britain (Louw, 1992, p. 21) This time could be seen under Schindler’s periodisation model as the ‘Machine-Tool Technology’ period. At this time energy is no longer powered by the craftsman but the machine, whilst information regarding dimensioning is provided by the operator with precision ensured by the design of the mechanised tool. (Schindler, 2007, p. 6) This point is well illustrated by Naysmyth’s illustration of the mechanised lathe. Here, the first ‘Hand-Tool Technologist’ struggles to provide energy at the same time as information. In order to achieve the desired profile with the analogue wood lathe, he must exert energy, whilst the second ‘Machine-Tool Technologist’ stands with one hand in his pocket as the other carves into the freely rotating element (Fig. 1.26). The mechanisation of timber processing brought a total shift towards sawn timber, whereby the directionality of the material is ignored. An axe no longer cuts along the grain of the wood, but rather a saw performs a linear incision through all the knots and shifts in grain inherent within the material. The 20th Century saw the evolution in timber construction from the era of the ‘craftsman’ to that of industrialised manufacture. This time in timber construction was ushered in by several inventions including the water powered saw (Fig. 1.27) and the circular saw (Louw, 1992, p. 21). Both were to capitalise on developments in axle design and manufacture to perform a translation impossible by the body; perpetual rotation. (Schindler, 2011, sec. 2) These new machines were combined and assembled as sawmills, resulting in cost savings as the process could now rapidly produce elements identical in dimensions. Like the hand tools, the basic element of machines developed through the industrial revolution were not necessarily new at that time. Axles have been used for thousands of years, but rather their large-scale mobilisation was to catalyse the proliferation of machines capable of producing repetitive timber elements.

Fig. 1.26. Naysmyth’s ‘Machine Tool Technologist’ (Above Right) Fig. 1.27. Water Powered Saw. Villard de Honnecourt (Right)

1.4 2x4 The age of industrial manufacture brought the standard dimensional lumber known as ‘two-by-fours’ (boards measuring 2 x 4 inches in section), which gave rise to the balloon frame and platform frame systems (Fig. 1.28)(Fig. 1.29), in which the carpenter’s own signature wood joining was replaced by nails, and where planks covered both sides of the close-knit frame, hiding the tectonics that were previously evident in the construction (Buri and Weinand, 2011, p. 57). Seigfried Giddeon proposed that the Balloon Frame marked the point at which industrialisation came to penetrate housing’ (Schindler, 2011, sec. 2). Whilst Frampton describes the balloon frame as a symptom of a dematerialization of built form, together with the all too literal mechanization and electrification of its fabric’ (Frampton, 1995, p. 22). Within the age of the machine, the information provided by the maker to the machine would ensure the production of many elements, all linear and all identical in dimension. This same linearity meant that any knot or grain that deviated from parallel to the blade was considered a defect. The forestry community became increasingly concerned with the growth of trees that would yield wood with predictable, controllable, classifiable and calculable characteristics (Schindler, 2011, sec. 2). In the UK there has been a wider proliferation of platform framing as an economical form of timber construction. ‘Uni-form’ scantling was used in cottages and other small buildings in the south-eastern counties of England during the nineteenth century. This American innovation was to be combined with a brick skin to provide weatherproofing and a contextual appearance. There remain to this day many advantages of the system including speed of erection, economy of labour on site and easy provision of heat insulation between studs (Brunskill, 1985, p. 81). Across the UK, platform framing remains one of the most popular forms of timber construction for the potential to save costs against many masonry and concrete frame systems (STA, 2018, p. 2).

Second Top Plate

Subfloor Ribbon Two Storey Stud

Joists Foundation

Second Top Plate

Subfloor Top Plate Single story stud

Sole Plate Foundation Fig. 1.28. Balloon Frame (Above Right) Studs extend across both stories. Fig. 1.29. Platform Frame (Right) Studs terminate at the first floor.

1.4 Wartime Innovation: Advent of the Mould There is much to be learnt in timber construction from innovations in aviation and product design during the war. The first and second world war catalysed innovation within laminated timber, with the de Havilland Mosquito being a prime example. The plane was constructed as an assembly of semi-monocoque modules, wherein a series of bent solid wood sections were wrapped in a ply-balsa-ply build-up to create a diaphragm, moulding the timber as opposed to machining it (Fig. 1.31) (Fig. 1.33) (Falconer and Rivas, 2013, p. 110). During this era, Charles and Ray Eames carried out many experiments in the lamination of constructional veneers, facilitated by the Kazam! Machine (Ngo and Pfeiffer, 2003, p. 32) The splints created for the US Navy were to pioneer a simple yet complex construction method, involving processes of moulding, milling and splicing which were previously unexplored (Fig. 1.32) (Wilk, 2017, p. 159). Both innovations were reliant of the development of rotary cutting machines whereby a log is spun on two axles at either side while a long thin blade cuts a sheet of uniform thickness(Fig. 1.30). Sheets of veneer between 0.4 and 3 mm thick could be layered in alternating orientations moulded with glue between them to form either rigid sheet material or bespoke forms.

Fig. 1.30. Rotary Cut Veneer (Above) A long thin blade cuts an entire log in seconds. Fig. 1.31. Mosquito Assembly (Below) Semi-monocoque components are assembled to form an enclosed plywood structure. Fig. 1.32. Eamesâ&#x20AC;&#x2122; Splint (Opposite) Utilising techniques from the textile industry, the Eames cut notches and holes to achieve the double curves form.

Nose

Half fuselage

Wing

Tailplane Fin

Engine mounting

Rear spar

24°

34 45 45° 120 107°

62 45 50 165°

33 62 1067

165°

323

45°

151

45°

87 189

Inner Ply skin

Laminated Outer spruce Ply Skin

Balsa wood

Fuselage Bulkhead Connection

Bomb site mounting

Spinner

3 bladed de Haviland Propeller Intake guard

Main wheel

Wingtip lamps

Fig. 1.33. Mosquito Construction 38

Rubber Channel

Perspex Double Glazing

Cockpit Connection

Ply skin

Ply strip Ply strips on inside

Balsa wood Rudder horn balance

Tail fin

Fuselage Central Connection

Tail plane

Rear Spar

Laminated spruce

Spruce Bulkheads

Plywood cladding

Plywood webbing

50ft spruce bars

801

20041

2208 567

10565 5901

4600 14000

Structural Framing Plan

1.4 Domestic Translation: Aalto and Mollino Wartime innovations in glued veneer structures were adopted by designers in the twentieth century. Some of the earliest examples of the manipulation of timber to create engineered structures were by Otto Hetzer in 1903 (Fig. 1.34). Architecture of the modern era was to leverage the tools of the machine age to realise buildings of increased economy and efficiency. The proponents of the international style were to favour concrete and steel as the materials of choice in addressing pressing post-war needs for housing and civic buildings. Alvar Aalto was a member of Congres International d’Architecture Modern (CIAM) and was committed to collaborating with pioneers of industrialised component construction. One thing that set Aalto apart from other Members of CIAM was his personal interest in timber construction. Early experiments in the more readily pliable bent metal tubing paved the way to several bent plywood experiments in close collaboration with Otto Korhonen. The bending experiments were rooted in a fascination with the biological properties of wood (Ando and Fleming, 2018, p. 3) (Isohauta, 2013, p. 272). Aalto was committed to translating his research at the sculpture and furniture scale to the design of his buildings. (Ngo and Pfeiffer, 2003, p. 15) The Finnish pavilion of the 1939 New York World Expo displayed the seminal patented ‘Fan Leg’ (Fig. 1.35) alongside a number of large experiments suggesting an interest in exploring the potential of bent wood technology at an architectural scale The ambition for the scaling of bent plywood furniture to that of the building can be seen in the stepped columns of the Ottaneimi Sports hall or the competition entry for the Helsinki Fair, 1934 (Fig. 1.36) (Isohauta, 2013, p. 274). Post war laminated furniture design exposed novel structural applications for laminated timber from which architecture could learn. Carlo Mollino’s experiments in plywood furniture proved fruitful between the 1940s and 60s. (Brino, 2005, p. 10) The vertebrae table designed in 1951 supports a sheet of glass through a structure that mediated between a shell and frame, meaning the structure is simultaneously surface and vector active (Fig. 1.37).

Fig. 1.34. Otto Hetzer’s first glue laminated member (Above Right) Patented 1903

Fig. 1.35. Aalto’s Fan Leg Stool Patent No. 28191 (Centre) Timber and veneer used in conjunction to create a form well suited to load distribution Fig. 1.36. Helsinki Fair Competition (Right) Tapered Laminated timber columns form the roof structure

105° 23° 50 110

175

185

175 128°

175

175 15°

2110 175

175

52° 175

175

52°

255

90 23° 190

155

580

Fig. 1.37. Mollino’s Vertibrae Table (Above and Right) An ingenious method of supporting a flat surface with a seemingly arched structure. Sheets manipulated in two dimension to create hollow areas of structure and bracing members.

1.4 Industrial Integration: Rogers and Hopkins High-tech architecture brought developments in the integration of engineered timber with sophisticated fixings. Frampton describes developments in the construction industry throughout the late 20th as an increased compartmentalisation into the Semperian elements of the podium, hearth, frame and envelope. He draws attention to the reduction in budget allocated to structure (frame) and significant increase in budget devoted to services (“hearth”). This condition was well recognised by ‘High-tech’ architects of the late 20th century as the requirement for servicing became expressed through the language of the building and even made to conform to the classical notions of proportion. The developments in technology also are evident in the adoption of tools for design. Making use of operational refinements which are increasingly dependent on the coordinating capacity of the computer and on the ability of architects to understand the constraints and tolerances of the procedures involved (Frampton, 1995, p. 386). The ‘High-tech’ design philosophy is evident in the Centre Pompidou designed in collaboration between Richard Rogers and Renzo Piano between 1971 and 1977 (Fig. 1.38) (Fig. 1.39). The project brought together a team of experts interested in developing new system of optimisation and prefabrication, with and understanding that a ‘Technological device is a cultural choice and not simply a matter of reductive logic.’ (Frampton, 1995, p. 383) Peter Rice, was the chief engineer for the project remarked. Rice’s intention to look at ‘old materials in a new way’ was well explored by other designers of the late 20th century. Michael Hopkins is one of several ‘High-tech’ architects to specify structural timber if a project demands a quality that the material can provide above others such as steel or aluminium. The Portcullis roof structure was an opportunity for the designer to explore a novel oak and stainless-steel diagrid (Fig. 1.42) Here we see that the technical sophistication of the structure is well beyond that of the balloon frame, however the material is still reduced to a dimensioned element (Fig. 1.40) (Fig. 1.41).

Fig. 1.38. Pompidou Centre Gerberette Detail (Above Right) Prefabricated discrete components for ease of site assembly. Fig. 1.39. Pompidou Centre Gerberette Isometric (Opposite Above) A primary rail allows the piece to rotate into place. Fig. 1.40. Portcullis House Detail (Right) Steel nodes allow for movement in all directions, with tie rods providing rigidity. Fig. 1.41. Portcullis House Isometric Study (Opposite Right) . Paired glulam elements are bolted to plate connections joining back to the nodes. 42

‘A technological decision is a moment in time where people, their background and their talent is paramount. By looking at new materials or old materials in a new way we change the rules’

(Rice, 1992, p. 12)

Bolted Plate Connection Glazing Bracket

Paired Glulam Lengths

Steel Node

Cross bracing

Lateral Bracing

1.4 Industrial Refinement: Renzo Piano Several years after the construction of the Pompidou Centre came Renzo Piano Building Workshop’s design for the IBM travelling pavilion (Fig. 1.42). Here the structural system observes the grain direction of a laminated timber element in order to meet the brief of ‘High-technology and high sensitivity’. According to Piano, ‘For today’s architects, chemistry has the same innovation value as welding had for architects of the past.’ whilst it was in the resourcing of a ‘special adhesive of…incredible strength’ that the IBM travelling pavilion was able to develop the laminated timber and cast aluminium system (Piano and Frampton, 2016, p. 48) Renzo Piano has been known to build on his experiences constructing boats to apply some of the tectonic language from naval architecture. Parco della Musica is testament to this notion, as the laminated timber structure supporting the downturned canopy tapers in response to weight distribution. In order to achieve this the fabricator staggered the veneers and milled the laminated assembly (Fig. 1.43) (Fig. 1.44).

Fig. 1.42. IBM Travelling Pavilion Detail (Above Right) Refined aluminium castings splice the glulam elements, with glued and bolted connection. Fig. 1.43. Parco de le Musica facade interior (Right) Tapered Glulam beams supported by steel props. Fig. 1.44. Parco de le Musica milled lamination detail (Opposite) Similar to the early ships, the elements are tailored once the desired curvature is established.

‘These days, the tools might include a computer, an experimental model, and mathematics. However, it is still craftsmanship – the work of someone who does not separate the work of the mind from the work of the hand.’ (Renzo Piano ,2016, p. 2)

Steel Pin Connection

Load-bearing Lamella

Outer Veneer

Steel Props

Excess Lamella (Wastage)

1.5. Information Finding Form: Frei Otto In the late 20th Century, tools for form finding and analysis introduced new opportunities for increasingly resource efficient long-span structures in timber. Frei Otto and Richard Burton of ABK were to develop a similar system to the IBM travelling pavilion some 4 years later with the direct integration of aluminium and Norweigian Spruce in the round (Fig. 1.45). The prototype house was one of many buildings constructed for the staff and students of the Parnham School. Ottoâ&#x20AC;&#x2122;s most influential timber building, however, was to be the Mannheim gridshell. Through physical form finding models, a lattice shell was developed with Architects Mutschler, Langner und Partner (Fig. 1.46). One of the largest built compression loaded structures, mechanical fixings were used to splice the lathes in order to cover the long-spans (Fig. 1.47) (Otto and Rasch, 2006, p. 141). Much later, Cullinan studio would develop a timber gridshell at the Weald and Downland Living Museum (Fig. 1.49). In this instance, extended finger joints would ensure a homogeneous connection between the lathes (Fig. 1.48) where Multihalle Mannheim demanded mechanical fixings (Harris et al., 2003, p. 438). Although the emergence of the timber gridshell catalysed further innovations in timber construction, the projects are a significant departure from the timber frame in that the sole purpose of a shell is to create enclosure as opposed to construct occupiable floors.

Fig. 1.45. Otto and the Prototype House (Above Right) Richard Burton [ABK) Ted Happold and Frei Otto with a model of the pioneering timber frame. Fig. 1.46. Mannheim Gridshell Hanging Chain Model (Centre) Physical simulation of forces at play on the shell structure. Fig. 1.47. Mannheim Gridshell Connection Detail Model (Right) A complex junction expressed between the shell and supporting columns.

Fig. 1.48. Downland Gridshell Pin Connection (Opposite Above) The lathes of the Weald and Downland Gridshell are free to rotate within the shell structure. Fig. 1.49. Downland Gridshell Super Structure (Opposite Below)

1.5 The Complex Assembly: Thomas Herzog Thomas Herzog was to progress the tradition of form finding in High-tech assemblies in timber in the Hannover expo of 2000 (Fig. 1.50), wherein a complex undulating diagrid roof (Fig. 1.52) is received by columns composed of four logs joined by prefabricated steel elements (Burger et Al, 2000, p.4). In this complex assembly, Herzog was able to integrate the surface active shell together with the table system of the logs. The joining of structural systems required large nodes, however, to translate the forces from one component to another(Fig. 1.51) (Fig. 1.53). Fig. 1.50. Hannover Expo Pavilion Exterior (2002) (Above Right) A series of log tables supporting a segmented shell roof. Fig. 1.51. Table and Shell Interface (Right) Plate connections join the two structural systems, with bolting and glueing taking place on site. Fig. 1.52. Roof Shell Structure (Below) The Hannover roof of 4 mirrored shells. Fig. 1.53. Hannover Pavilion Nodes (Opposite) Two primary steel connection assemblies each act as a frame system in themselves.

1.5 Digital Turn: The 21st Century Research Group Schindler’s third and final phase of ‘Information-Tool Technology’ in the periodisation model is that of the 21st Century. In this ‘wave’ the human becomes the creator of the process while the machine is the creator of the products. (Schindler, 2007, p. 12) Where the circular saw is set to a position, it must be altered for every cut that is not precisely that of the previous. Entirely digital manufacturing methods now afford the production of elements which integrate with an assembly displaying continuous differentiation (Fig. 1.54). Several research groups have experimented with the application of wood with emerging computational tools. Achim Menges’ ‘Aggregated Lamination’ explored the opportunities of bending in two directions (Fig. 1.56). This utilised and challenged the anisotropic properties of the material. Researchers at CITA studio have evolved methods of analysis, modelling and fabrication in the unique branching structure of ‘The Rise’ (Fig. 1.55).

‘The design opportunities that are enabled by the heterogeneous make-up of wood are usually completely neglected in today’s construction practice. Wood is dumbed down to just another dimensioned building element.’ (Menges, 2012, sec. 1)

Sheet Modification

Element Nesting Fig. 1.54. Numerical Manufacturing strategies for Timber construction (Right) 3 main commercially viable methods of processing timber for construction using ‘information tool’ technology: Sheet modification with a CNC router, nesting of elements to be assembled as larger components and bending to an approximation before 5-axis milling. Fig. 1.55. The Rise (Opposite Left) A lightweight rattan structure based on research into the phototropic, geotropic and thigmotropic growth patterns of plants.

Fig. 1.56. Aggregated Lamination (Opposite Right) Achim Menges’ research with Harvard students into a complex assembly of prefabricated, 3 dimensionally pressed laminations.

Bending and Trimming

1.6. Section Conclusion

Timber has proven to be fit for purpose as a structural material for centuries, and through well directed research, there has been much progress within the engineering and construction of timber products. Timber is a unique material in that its natural behaviour at a biological scale has direct implications on the mechanical properties. If the cells of the material are compressed, the material becomes more firm as a result ( Jeska et al., 2014). If the cells are subjected to steam, the lignin softens and allows the cellulose and hemicellulose to pass freely, meaning the material will become more pliant (Peck, 1957). These chemical properties, among others, vary greatly between species and specimens, giving the material unexpected behavioural qualities. The previous case studies demonstrate the products of the designers seeking to harness these qualities in the hope of improving the products and places we encounter. Christoph Schindler’s periodisation model provides a useful lens to view the evolution of the timber frame. A limitation, however, is that the model favours technology. From the case studies explored in the literature review, one can conclude that a construction system evolves in response to technological development as well as human need. The technologial innovation demanded by the first and second world wars were later adopted in furniture and quickly erected timber frames in response to population growth. Today there is a need to translate innovation within the building industry to respond to the most pressing crisis of the 21st century; climate change. (Organschi and Waugh, 2014, p. 5). In the age of information-tool technology, the machine takes on information in a way that those of the previous era were not able to. It would be a misconception, however, to assume the increased intelligence of the tool demands less intelligence from the designer. Renzo Piano remarks on the topic of craft and technology: ‘These days, the tools might include a computer, an experimental model, and mathematics. However, it is still craftsmanship – the work of someone who does not separate the work of the mind from the work of the hand.’(Piano and Frampton, 2016, p. 3). Whilst Brunskill proposed that ‘A revival of Cruck Construction may be seen in the use of laminated timber frames’ is we are to successfully negotiate the need to recognise tradition and pursue innovation. He further posits that ‘We have to accept in the pulls of tradition and innovation, tradition suggesting the well understood, the well-proven solution to a problem, innovation suggesting a new, untried possible more economical solution to a problem which may not be familiar at all’ (Brunskill, 1985, p. 84).

‘We have to accept in the pulls of tradition and innovation, tradition suggesting the well understood, the wellproven solution to a problem, innovation suggesting a new, untried possible more economical solution to a problem which may not be familiar at all’ (Ronald Brunskill, 1985, p.84)

Fig. 1.57. Downland Gridshell Interior (Opposite)

Sectionâ&#x20AC;&#x201A;2. Abstraction: Lamination Experiments 2.1. Introduction From the historic and contemporary advantages of timber frame construction, the thesis takes the age of information tool technology as a point of departure for physical testing of the material. The overarching ambition of the experiments are to uncover unique structural solutions to spanning and connecting engineered timber elements . All the tests are aimed at exploring a dialectic of maximising natural, anisotropic properties of the material together with a high level of manufacturing intelligence. This dialectic is further explained in the following section proposing a continuum to determine a productâ&#x20AC;&#x2122;s propensity to allow for both criteria to be explored. The studies explore contemporary strategies for developing forms and structures in the application of veneers and strands both as a scale representation of larger products and latterly the 1:1 application of veneer to construct structural components, engaging with the limitations and opportunities of the natural material (Fig. 2.1).

Fig. 2.1.

Lamination Experiment Series (Opposite)

2.2. Engineering Timber Processes and Products Despite the many standing examples of timber construction since the middle ages, wood became neglected as a building material in favour of the more readily industrialised production methods of steel and reinforced concrete. Developments in the industrialisation of timber products have proliferated since the latter 20th century including standardised and quality controlled glued connections. ( Jeska et al., 2014) . Timber is currently commercially processed in a number of ways for timber construction (Fig. 2.4). Marraâ&#x20AC;&#x2122;s 1972 model demonstrates that we are able to process the material from the log to the cell (Fig. 2.2). This thesis interrogates the value of this opportunity, demonstrating that as the manufacturing potential increases so do the anisotropic properties of the material (Fig. 2.3). This is clear when we observe that Medium Density Fibre Board is not a suitable product for the construction of beams, as it would surely disintegrate when placed under any substantial compression or tension. The area of greatest interest for the thesis lies at the centre of the model: Veneers and Strands. These products have evolved rapidly in the 21st century, with Laminated Veneer Lumber and Parallel Strand Lumber becoming increasingly sought after for their strength and manufacturing potential.

Log

Fig. 2.2.

Wood Materials (Marra, 1972) Timber is processed from the raw log to the molecules.

Fig. 2.3.

Balancing Natural Properties and Manufacturing Potential Strands and veneers provide an interesting opportunity to engage with refined fabrication processes whilst retaining many natural anisotropic properties of timber.

Fig. 2.4.

(Opposite) 4 of the most common engineered products (CLT, Glulam, LVL and LSL) commercially used to construct buildings. New machines are being regularly develop new ones.

Veneer

Thinnings

Plywood

Large Logs

Laminated Veneer Lumber

Plank

Strand

Glue-Laminated Timber

Laminated Strand Lumber

Cross-Laminated Timer

Parallel Strand Lumber

Anisotropic Properties

Chip Oriented Strand Board

Fibre Medium Density Fibre Board

Manufacturing Potential Products of Interest

Engineered Timber Products Manufacturing Processes

Cross-Laminated Timber

Glue-Laminated Timber

Strips are finger jointed for increased lengths

Logs cut to thin strips

Adhesive applied strips

Cross layered strips are subject to compression from all axes

Laminated Veneer Lumber

Soaking

Adhesive applied to stacked veneers

Adhesive applied and planks are compressed.

Logs cut to planks.

Glued members are cut to size.

Planing and sanding.

Laminated Strand Lumber

Industrial lathe veneer extraction

Compression

Logs are soaked and heated.

Debarked logs are subjected to stranding, drying and adhesive blending.

Soaked logs are debarked.

Adhesive blended strands are subjected to steam compression to form sheet material. 57

2.3. Lamination Experiments Spliced Lamination Context In principle, glue joints represent the most efficient way of forming a structural connection between two elements ( Jeska et al 2014, p. 50). The study looks to apply lamination techniques observed in furniture design and to address the issue of scale change by introducing a splice connection through the staggering of lamellae.

Objectives

‘In principle, glue joints represent the most efficient way of forming a structural connection between two elements.’ Jeska et al 2014, p. 50

Design Develop a detail at the transition between floor, wall and frame connection Investigate splicing for laminated timber elements

Fabrication Create an efficient cutting list for sheet fabrication Develop a form-work to withstand sufficient pressure

Process Description Following the modelling of NURBS surfaces in Rhino 3D (Fig. 2.8), cut files were generated from the outline of the ‘unroll surface’ command. Alternating grains were established through layer management in order to allow the grain direction to inform the structure (Fig. 2.6). Laser cut sections were laminated to form the mould (Fig. 2.5), with pressure applied in the x and z axis by clamps (Fig. 2.7).

Evaluation Interesting structural conditions in the filleted channel between wall and floor (Fig. 2.9), increased thickness of wall to support the floor as well as functioning splice. The integrity of the grain direction is not preserved across the splice, whilst the area of wall supporting the splice is a wasteful use of material. The form is very material intensive, whilst the splice could lead to de-lamination of members.

Fig. 2.5.

Mould Assembly

Fig. 2.6.

(Above) 3 part laser cut plywood mould. Cutting Schedule (Right) Alternating grains cut from a single sheet of oak veneer.

Fig. 2.7. 58

Clamping Strategy (Opposite)

Grain Direction

Fig. 2.8.

Spliced Lamination Assembly (Above) 40 unique sheet of veneer pressed in one.

Fig. 2.9.

Spliced Lamination (Opposite) Wall to floor connections serves to strengthen the sheet, acting as a beam and create space for occupation.

2.2 Continuous Cruck Lamination Context The combined column/rafter component described in Hetzerâ&#x20AC;&#x2122;s 1903 patent (p. 38) demonstrated the potential to produce curving forms in timber without wastage (Pascha 2014, p.37). The study explores the idea of further developing Hetzerâ&#x20AC;&#x2122;s integration of structural elements by proposing a column and floor connection in a single lamination, based on the geometry of a typical Cruck frame (Fig. 2.10).

Objectives Design Taper column according to vertical load accumulation. Achieve a homogeneous connection between floor and column

Fabrication Efficient nesting of veneers. Laminate in a single mould

Process Description Nets extracted from a Rhino 3D model and cut from a single sheet of oak veneer (Fig. 2.11)(Fig. 2.13). Moulds were cut and sanded from laminated MDF pieces based on templates extracted from the 3D model (Fig. 2.12).

Evaluation Interesting structural conditions in the filleted channel between wall and floor, increased thickness of wall to support the floor as well as functioning splice (Fig. 2.14).

Fig. 2.10. Reviving the Cruck (Above) Achieving the tailored form of the Cruck barn without milling found timbers. Fig. 2.11. Cutting Schedule (Right) Nested Laser cut piece mean the tapered profile of one strip is the widening of another. Fig. 2.12. Mould Assembly (Opposite) 3 Part MDF mould assembly used to press the piece in one move. A staggered process would have greatly improved the quality of the finished product.

Fig. 2.13. Continuous Cruck Lamination Assembly (Above) 55 unique sheets were nested in laser cut veneer leaves and glued with a 3 part MDF Mould Fig. 2.14. Continuous Cruck (Opposite) A homogeneous connection between column and floor profiles tailored without milling techniques. 64

2.2 Additive Lamination Context Based on observations into the structure of a tree the study recognises the inefficient distribution of material seen in most engineered timber elements and proposes a method closer to additive manufacturing as thin sheets of veneer are introduced according to the structural requirements. A braced bifurcation was established as the means of introducing a connection without mechanical fixings, wherein the forces of tension and compression and balanced and transferred directly along the lamella.

Objectives Design Tapered timber profile with minimal waste material Develop a braced bifurcation Fig. 2.15. Veneer Species

Fabrication Construct a mould to apply sufficient uniform pressure Minimise gaps at the point of overlap between veneers

(Above) 4 species of veneer in the additive lamination clockwise; Oak, Beach, Birch and Larch. Fig. 2.16. Cutting Schedule (Opposite Right) Highly efficient material use through laser cutting techniques. Fig. 2.17. Strip Schedule Automation

Process Description

(Below) Grasshopper definition used to produce and automated shedule of strips base on a basic space filling algorithmm

Grasshopper definition was developed to draw and schedule the arrayed veneer sheets (Fig. 2.17)(Fig. 2.15). The sheets were laser cut into strips of a uniform thickness, modulating in length (Fig. 2.16). The piece was constructed in three parts to allow the glue to set under pressure.

Evaluation It was very difficult to glue the pieces together, by the time the last laminations were being placed, the PVA glue had begun to set on the earlier veneers, which could have been addressed by a slower setting glue. The piece required little finishing and the connection has remained strong although the introduction of a dowel or biscuit joint would have further strengthened the connection between the three pieces (Fig. 2.19). Oak

Birch

Beech

Ash Compiled Geometry

Fig. 2.18. Additive Lamination Assembly (Above) 300 strips of veneer were used to construct the additive lamination, with a three part plywood mould Fig. 2.19. Additive Lamination (Opposite) Unique spatial qualities are achieved with the combination of different species within a single element. 68

2.2 Cross-Laminated Shell Context ‘Load-bearing structures, e.g. shells, can be built with a distinct economic advantage over other forms of construction with solid materials.’ ( Jeska et al, 2014) The study recognises the insulating properties in cross-laminated timber, and applies them to a shell structure, potentially achieving a great span and increased strength through the even distribution of forces throughout the element.

‘Loadbearing structures, e.g. shells, can be built with a distinct economic advantage over other forms of construction with solid materials.’

( Jeska et al, 2014, p. 200)

Objectives Design Develop a surface-active self-supporting structure from a single layup of three sheet of 3D veneer

Fabrication Establish the minimum bending radius with workshop constraints

Process Description A form was milled from polyurethane foam to meet multiple radius’ of 25mm, 30mm and 35mm with the sheet material measuring a thickness of 1.4mm (Fig. 2.20). Following the application of PVA glue between the sheets, the layups were assembled with alternation grains (Fig. 2.25) and pressure was applied with the vacuum Bag Press, with each piece left for 1 hour in the vacuum (Fig. 2.22).

Evaluation The material captured the double curvature of the 35mm and 30mm radius pieces (Fig. 2.21) (Fig. 2.24) (Fig. 2.26), with the 25mm radius causing the piece to overlap (Fig. 2.23). A smoother surface for the form such as aluminium would allow the strips to readily slide whilst a second part to the form could prevent the sheets from overlapping.

Fig. 2.20. Shell bending radii (Above) 3 shells were made in order to understand the limitations of the material. Fig. 2.21. Shell Shrink Action (Centre) The thin strips shift alongside each other, pulling in the centre of each edge. Fig. 2.22. Shell Pressing (Right) Vacuum Bag press setup Fig. 2.23. Shell Radium Test (Opposite Above) The piece failed around a radius of 25mm.

Fig. 2.24. Cross-laminated Shells Arrangement (Opposite Right)

35mm

30mm

25mm

Fig. 2.25. Cross-laminated Shell Lamination Assembly (Above) 3 shells of 3 sheets of 3D veneer in alternating orientation on milled polyurethane foam moulds.

Fig. 2.26. Cross-laminated Shell (Opposite) Experienced at different scales, the shells could define enclosure or simply suggests organisations as alterations in ground plane.

2.2 Cross-Laminated Surface Context Timber is a material defined mainly by the direction of growth. This test looks to develop a rigid surface-active structure from cross-laminated strips, with a high level of curvature in all directions, to establish the limitations of the anisotropic material.

Objectives Design Develop a complex surface-active structure from a single layup of three sheets of 3D Veneer

Fabrication Establish the minimum possible radius captured with a single part mould and a vacuum bag press

Process Description A 3d surface was developed in Rhino 3D based on capturing a range of concave and convex radii from 10mm to 40mm (Fig. 2.28) . The double curved form was 3D printed from PLA in 4 segments (Fig. 2.27) and held together within a plywood base (Fig. 2.29). PVA glue was applied between three sheets of 3D veneer in alternating direction (Fig. 2.30) and the layup was overlaid on the form before being compressed in the vacuum bag press.

Evaluation The material captured much the convex curvature, with less information being captured in the concave curvature (Fig. 2.31). A second part to the mould would have meant there was little difference between the concave and convex areas.

Fig. 2.27. 3D printed Form Assembly (Above Right) A 4 part mould printed with an Ultimaker 2+ without the need for support material Fig. 2.28. Radius Range (Right and Opposite) Section through the surface designed to capture radii from 10mm up to 40 mm in order to establish the limitations of the material Fig. 2.29. Raw Sheet Layup (Opposite Above) Layup of 3D veneer was arranged cross grain in 3 layers, whilst the 3D was housed in a notched plywood base. 74

40 35 30 25 20 15 10

Horizontal Strips

Vertical Strips

3D printed form

Plywood Housing

Fig. 2.30. Cross-laminated Surface Lamination Assembly (Abover) 3 layers of veneer in alternation directions aseembled on a 3D printed mould. Fig. 2.31. Cross-laminated Surface

(Opposite) At a 1:20 scale, the surface takes on an uncanny quality as though something were moving behind a curtain of timber.

2.2 Seamless Column Context Through inclining the surface toward the direction of the acting force by means of folding or curving, it is possible to reconcile the opposites or horizontal efficiency in the resistance against gravitational forces (Engel, 1981). The study looks to combine an understanding of ability for corrugation in a surface to resist bending failure and the fluting of a column to resist buckling with the requirement for continuity of lamella in a laminated timber structure composed of strips.

Objectives Design Develop a structure capable of spanning between two support locations and supporting a floor with a single layup of 3 layers or 3D veneer running in one direction.

Fabrication Create geometry suitable for a multi axis CNC. Develop method of fixing the sheets in place before the application of the bag press.

Process Description The element was modelled in Autodesk Maya before being exported as geometry suitable for the toolpaths of a CNC mill (Fig. 2.34)(Fig. 2.35). Embedded within the modelling process was an understanding of the stresses active in the connection (Fig. 2.32) (Fig. 2.33) and that the lamella count should be maintained by ensuring the circumference of the fluted column was equal to the length of the corrugated surface edge. Due to the limited height of the drill bit, the pieces were segmented and glued together. Three sheets of 3D veneer were placed together with PVA glue in a single direction (Fig. 2.36) and the layup loosely formed around the form with use of a clamp to pinch the surface together at the rear of the fluted cylinder. Pressure was applied with a vacuum bag press.

Evaluation The material captured all the convex curvature, with less information being captured in the concave curvature (Fig. 2.37). A second part to the mould would have meant there was little difference between the concave and convex areas.

Fig. 2.32. Stress Visualisation of a typical column and slab system. (Above Opposite) Curvilinear stress lines revealed when analysed with supports at each column base. Fig. 2.33. Canopy Utilisation. (Opposite Centre) Areas of tension and compression revealed in the surface active structure. Compression is focused around the edges and on the concave area of the overhang.

Fig. 2.34. CNC Mould (Below Opposite) Two Part mould glued together from Artfoam. Fig. 2.35. Mould Toolpaths (Above) Roughin pass carried out by a 10mm flat bit (red. A high level of fidelity was captured by the 3mm ball nose drill bit in the smothing pass( blue) 79

Fig. 2.36. Seamless Column Lamination Assembly (Above) 3 sheets of 3D veneer were glued in one direction to gain maximum curvature. Fig. 2.37. Seamless Column

(Opposite) A fluted column transition to a corrugated floor with unexpected folds and crevices resulting from the material behaviour.

2.2 Cross-Laminated Tube Context The disadvantages of timber structures built exclusively from solid timber sections could be overcome by producing efficient timber sections with different cross-sectional forms in a similar way to the standardised steel or plastic sections manufactured by industry ( Jeska et al., 2014, p. 210). The study looks to create a curved cylindrical timber element which is braced against buckling through cross lamination, utilising considerably less material than a solid element milled of the same dimensions, and constructed from a renewable resource unlike plastic or steel (Fig. 2.39).

30Â°

Objectives

R170

Design Develop a hollow tube with an angled profile.

Fabrication Create a form with a profile radius and bend angle suitable for the 3D veneer to assume

Process Description Similar to the previous experiment the design acknowledges the need for a consistent lamella count within the cylinder, ensuring structural continuity (Fig. 2.38). A cylinder was milled by hand from polyurethane foam according to a circular template. A layup of 4 sheets of 3D veneer were arranged in alternating directions (Fig. 2.41) and taped in place as a first fix before having pressure applied in the vacuum bag press (Fig. 2.40). The piece was left to partially set before being temporarily removed in order to trim the overlapping veneers.

Evaluation The strips running in the long dimension readily assumed the form, whilst those placed in the cross grain tended to rise at the joint, creating a visible ridge along parts of the cylinder (Fig. 2.42). This issue could possibly have been overcome by increasing the length of overlap and in turn the amount to be removed after the partial setting.

Fig. 2.38. Tube Profile (Above) The a bent tube is commonly seen in steel construction, but impossible to fabricate by turning wood. Fig. 2.39. Potential Hollow Tube Application (Right) A hollow beam with integrated services. 82

Fig. 2.40. Vaccum Bag Press (Opposite) Vaccum bag setup with felt to prevent piercing.

100

Fig. 2.41. Cross-laminated Tube Lamination Assembly (Above) 4 sheets of 3d veneer were used to create the hollow tube around the Polyurethane foam form. Fig. 2.42. Cross-laminated Tube

(Opposite) A hollow section from wood veneers using a fraction of the material in comparison to a milled piece of solid timber.

2.2 Bifurcating Tube Context The experiment in departs from the current understanding of timber as a solid material, requiring machines for cutting, planing, notching and sanding, but instead looks towards composite construction methods such as fibre glass or carbon fibre to create a strong and lightweight component suitable for a hollow frame assembly.

Objectives Develop a homogeneous hollow bifurcating tube Create a collapsible form around which to bend the veneer

Process Description With an understanding that the grain direction within a tree fork demanded unviably tight bending radii, the form was developed in Autodesk Maya and Analysed in Rhino 3D (Fig. 2.43). Pieces for a collapsible form were extracted and prepared for milling with the CNC router (Fig. 2.44). The milled pieces encased a rigid frame constructed from medium density fibreboard so as to retain the form under the high pressure of the vacuum bag (Fig. 2.46) The first later of 3D veneer were held together with thin strips of masking tape (Fig. 2.45), whilst regular veneer collars provided strength in cross lamination (Fig. 2.47). Considerable breakout occurred in the 45 degree bend, with the fibres ultimately glued individually.

Evaluation The pipe was successful in creating a homogeneous hollow connection from a wood product(Fig. 2.48), whilst the collapsible mould worked effectively. Further finite element analysis of the structure could reveal further redundancies.

Fig. 2.43. Forking Grains Comparison (Above) An ideal grain direction based on the growth patterns evident in a tree (Ozden et al. 2017, p. 905) proved too tight of a radius so a revised forking grain is proposed. Fig. 2.44. Collapsible Mould Assembly (Centre) A 16 part mould of an MDF and dowel frame centred around a node is clad in polyurethane foam. Fig. 2.45. Veneer Application (Right) A process of partly drying the glue allowed for corrections during the fabrication process.

Fig. 2.46. Collapsible Mould (Opposite) Elastic fishing wire ensure the pieces were fixed together without the need for adhesive.

Fig. 2.47. Bifurcating Tube Lamination Assembly 6 sheets of regular veneer and 6 sheets of 3D Veneer were glued and pressed in stages to ensure an even coverage. Fig. 2.48. Bifurcating Tube

A fully homogeneous connection displaying some failure in bending of the tighter radius.

2.4. Section Conclusion

Recognising the experimental working methods of Aalto and Otto, the tests are testament to the research value of physically testing structural principles at scale. The methods allowed for the quick development of ideas in a process that engaged the hands of the designer. These processes have provoked thoughts on alternative spaces for inhabitation, leaving a resource to be drawn upon in the scaling of laminated timber techniques. A recurring theme was that of the homogeneous connection. The use of a glued connection as opposed to a pin or plate connection generated more complex and tailored structures. The Seamless Column and Bifurcating Pipe were resource efficient through geometric complexity. Current large scale forming methods are limited, particularly in the construction of doubly curved components, however, multi-point surface moulds are increasingly common within the aviation industry and would be of great use in architecture, should more complex and doubly curve timber surfaces be specified in the industry. The latter tests involving the 3D veneer show that high strength and very small bending radii can be achieved with the product as it exists at 1:1, however the components that emerge prove difficult to integrate with a wider system of larger laminated timber elements necessary for the larger load-bearing structures.

Fig. 2.49. Lamination Experiment Series II (Opposite)

Sectionâ&#x20AC;&#x201A;3. Synthesis: Design Studio Project 3.1. Introduction The third and final section of the thesis is dedicated to synthesising knowledge and skills from the previous two sections, testing a design methodology that pairs material studies and digital tools for analysis and fabrication. In recent years much of the conversation around timber construction has been focused on residential frame developments or structurally ambitious pavilions. In designing a civic building from structural timber, the project places the material in the public domain, addressing the current lack of confidence in itâ&#x20AC;&#x2122;s potential. The following section is intended to develop the design as knowledge is gained from the structural potentials and limitations in long-span timber construction. The process described is broadly chronological, documenting the stages of design and analysis, followed by the fabrication of a two part structural assembly. The components are selected to represent the two main means of connection within the structure: the homogeneous laminated fork and the wedged scarf joint.

3.2. Project Description

Overview The improved speed of connections to Northern Britain afforded by HS2 are under scrutiny to achieve the wealth and opportunity promised. An alternative terminal at London Euston would provide a Market Hall (Fig. 3.2) for newly connected and independant vendors and Wintergardens (Fig. 3.4) to create a civic space that will benfit the community and the country.

The wintergardens and typical station bays demand a linear long-span structure (Fig. 3.3), with openings to allow for movement between bays (Fig. 3.1). The market hall provides an opportunity to develop a multi-storey timber frame to house transient markets, permanent ateliers and high level dining areas.

5 6

Fig. 3.1.

East Elevation (Previous) Eversholt Street Elevation

Fig. 3.2.

Market Hall Section Early section exploring the potential for multiple storeys of retail and dining above the station platforms. Building Overview Currently under development, Euston station is in need of upgraded services

Fig. 3.3.

Fig. 3.4.

Wintergarden Interior Study Early concept to building interior.

1. Branching Roof Structure 2. Upper Canopy 3. Lower Canopy

4. Branched Entry 5. Connecting Walkway 6. High Speed

Train Platform 7. Dining Hall 8. Wintergarden 9. Regional Connection Platform 10. Primary Footing

Exposed train entry Western pedestrian entrance

Primary structure Enclosed Market Hall

Outdoor Covered Market

Plaza Pools

Underground Entrance

Planting/ Bust Interchange

3.3. Design Development 16 0

Structural System The primary structural system is that of a vaulted branching structure, whereby vertical and horizontal structure emerge from a central â&#x20AC;&#x2DC;trunkâ&#x20AC;&#x2122; and intersect to allow for upper level circulation (Fig. 3.7). The system recognises the limitations often imposed on timber construction based on the required size of connections in order to maintain structural continuity ( Jeska et al., 2014). This is addressed by minimising moment connections and instead using bifurcation as the primary method of joining elements.

6000

0 18

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6000

The entire super structure measure 280m x 150m (Fig. 3.6) and is broken down into 100 frames with dimensions varying from an arch span of between 16 and 38 metres (Fig. 3.5) based on the civic functions within the building and a module width between 16 12 and 28 metres in response to the circulation demands above 00 and below ground. The heights of the frames vary between 6 and 0 20 metres, in line with the spanning distance.

0 18

Fig. 3.5.

Minumum and Maximum Module Spans (Above Right)

Fig. 3.6.

Superstructure (Above)

Fig. 3.7.

Typical Structural Bay Assembly (Opposite) Colour Coded diagram identitfyin the structural systems integrated within a single bay.

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Stone/Concrete Vaults

Shell Structure

Secondary Branches

Hollow Beam Walkways

Roof Structure

3.3 On Branching

â&#x20AC;&#x2DC;In nature, standardization is almost exclusively applied to the smallest possible unit, the cell. This results in millions of flexible combinations that never become schematic. It also results in unlimited riches and perpetual variation in organically growing forms. We must follow the same path in architectural standardization, too.â&#x20AC;&#x2122;

E E D D C C

(Alvar Aalto, 1935)

Bending

Due to the variations in structural demands within the tree (Fig. 3.11), variations in profile are visible across every member (Fig. 3.8). Within the tree itself, it is understood that the trunk will bifurcate in one of two ways. A strong tree fork is a codominant stem, wherein the grain between the two equally sized branches is continuous and interlocked. A weak tree fork arises from a lack of interlocking grain resulting in bark inclusion, known as a compression fork (Fig. 3.9). Compression forks are to be avoided in forestry and are deemed unsafe in public forests due to the likelihood of splitting (Lonsdale, 2000, p10).

Fig. 3.8.

Effective Fork

Compression

Good and Bad Forks (Centre) An effective fork allows for forces to be transferred in all directions, whilst a compression fork is liable to split the branches are subject to bending.

Fig. 3.10. Areas of tension and Compression within the log (Right) A piece of wood performs twice as well in tension parralel to grain than in compression.

Profile Differentiation (Above) An fibres diverge with altitude, the profiles of the members shrink to maximise surface area for photosynthesis.

Fig. 3.9.

Bark Inclusion

Fig. 3.11. Areas of tension and Compression within the tree (Opposite) A tree is under stress from any direction due to variable wind loads, allowed for by the homogeneous structure.

Tension

C Compression Fork

3.3 The Fork A crucial aspect of timber framing is the connection between members and the ability for the members to transfer forces of tension and compression (Green et al., 1999, sec. 4) In the tree, members are joined through a homogeneous connection as the fibres have grown from the same point at the base of the tree. (Reinprecht, 2016, p. 119) One method of reducing the need for mechanical fixings in a timber frame is to bifurcate a single laminated element as per the Physical Branching Study (Fig. 3.13) wherein a single sheet of 3D Veneer is split and re-joined at various points along the length, suggesting a structure that may create enclosure more than triple the width of the base by simply bifurcating 30 degrees over three levels. A wider angle of bifurcation and an increased number of levels would achieve a greater base to top width ratio (Fig. 3.17). The requirement to brace these bifurcations is addressed through the introduction of a third lamination, enclosing the connection as both a single node and a set of three members (Fig. 3.12).

Fig. 3.12. Branching Studies (Right) Early studies exploring the possibility of a tree structure based on a need to create openings for daylighting and the intersection of horizontal structure. Fig. 3.13. Physical Branching Study with Danzer 3D Veneer (Opposite) Very thin strips of veneer bifurcate from the single sheet to create openings. As the bending radius of a piece of timber is always roughly 200 x the thicknes, this rechnique could be used to develop the glulam system in the overall.

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0Â°

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3.3 Designing for Stress In any structural system there are compressive and tensile forces. These forces and be understood through analysis (Hunt, 1997, p. 10). In the studio there is a need to synthesize an understanding of the structure as a system with the understanding gained in relation to the material performance. The material distribution within the structure was established by 3 stages: 1.

Overall form and support definition

Principle stress line definition observed through Karamba 3D

Karamba 3D is reliant upon an informed decision as to the location of supports within the system in order to determine the primary stress lines. Although the system in ultimately a frame, the material distribution is informed by analysing the spanning vaults and shells (Fig. 3.14). The system is such that a single point at the base of each side of the arch is fixed in all directions. Support locations at the interface with the adjoining arch can move perpendicular to the spanning distance. This means that the terminal frames are cantilevered, giving a different reading of tensile and compressive forces to that of the frames supported on both sides. (Fig. 3.16).

3. Synthesis of stress line analysis with branching logic

Reference Geometry for Analysis

Support Locations

Loads (Gravity)

Structural System Defninition (Shell)

Material Selection Fig. 3.14. Stress Line Visualisation (Above and Opposite) Karamba 3D is an out of the box solution to study forces within a structure, allowing the designer to iterate structural concepts without specialist input. Mechnical properties of the material are taken into account with the input of a mesh geometry, support locations, structural system definition (Shell) and the impacting loads (gravity) 102

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3.3 Rationalisation

Fig. 3.15. Stress Line Rationalisation (Above) Unfolded Arch showing the the rationalised structure informed by the stress visualisation. The homogeneou structure is intentened to allow for both tension and compression forces within a single timber frame.

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Fig. 3.16. Typical and Cantilevered Stress Line Rationalisation (Opposite) Different loads conditions influence the material distribution as the cantilivered frames are supported in all directions at the footings and in the horizontal and one lateral axis at the the roof line on just one side.

Horizontal Support

Vertical Support 105

3.3 Intersection: Material and Analysis

The stress line visualisation indicated that the tension and compression within the shell are always perpendicular, with the density controlled by a numerical slider within the Rhino / Grasshopper interface. The definition populates the shell surface with a series of points, from which the vectors of the forces acting in both tension and compression are determined. These vectors are then traced to their terminal locations at the edge of the surface.

° ° ° 75 75 75

The surface was converted to a mesh in order to be analysed through Karamba 3D with the framing plan based on the primary stress lines (Fig. 3.15). A similar work-flow to that adopted in the experimental Volu Dining Pavilion by Zaha Hadid Architects (Bhooshan, 2017). Through this process it was possible to determine the areas within the form under stress in both tension and compression.

The Karamba 3D simulation provided a useful suggestion for the directionality of the members. This information is then synthesised with the branching logic to form the framing plan. Finite element analysis of a surface based on the outline of the total performing lamella reveals areas of tension and compression similar to a tree (Fig. 3.18).

° ° ° 60 60 60

Fig. 3.18. Typical Roof Structural Bay (Opposite) Finite Element analysis of a surface based on the outline oth the total performing Lamella, showing areas of tensiona and compression similar to a tree.

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45° 45° 45°

Fig. 3.17. Roof Structure Types (Right) Dependant on the spans within the bay, the angle of the banching structure will vary

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3.3 Modelling Modelling is an important aspect of the digital work-flow in the development of a long-span timber structure for the age of information tool technology. Today, we are in a position to develop the performance and the form of a structure together (Mayne, 2012), as a digital model can be burdened with increasing parameters for performance within the digital environment. Much of the recent research into free form glue laminated timber assemblies have been developed through models reliant on a â&#x20AC;&#x2DC;master surfaceâ&#x20AC;&#x2122; (Poinet, 2016). This is known as a 2.5d working method, whereby the designer can refer to a NURBS surface and generate geometry for the structural members based on a determined offset in the normal direction of a given point along the surface. This method has been used in several built precedents including the Centre Pompidou Metz and the Haesley Nine Bridges Country Club (Sheurer, 2010). The system developed in this thesis explored methods of modelling a frame system based on a three-dimensional set of points (Fig. 3.21). This way the structure was analysed based on the vectors from point to points. Connections are made within the rigid frame as opposed to the node, where the elements are free to bend as the material dictates. These vectors are offset based on a graph map (Fig. 3.19) in order to establish the typical branching structure (Fig. 3.20) (Fig. 3.26), which is then adapted to generate the multi-storey system (Fig. 3.22 - Fig 3.25).

Fig. 3.19. Typical Bay Graph Map (Above) In adopting a branching structure, the lamella can be traced from the footing to the top of the structure.

Fig. 3.20. Typical Roof Structural Bay (Right) A branching canopy developed through synthesis of the sress visulaistion and lamella distribution. Fig. 3.21. Modelling Sequence (Opposite) 6 steps to generate the geometry basde on the rationalised stress line information; Point Extraction, rigid curve network, Lamella Offset, Spline Generation, Surface Generation, Depth Offset. 108

Tension and compression intersection points are mapped onto the original NURBS surface analysed in the global stress line visualisation.

A network of lines connects the points.

Curves are offset according to the lamella count indicated in the graph map.

2-degree splines are generated from the upper and lower segment of each curve, with the point to point lines providing the vector for the spline control points.

Single surface generated for each lamella cluster.

Profile of lamella cluster is extruded along the surface and offset normal to the surface.

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3.3 Multiple Storeys: The Market Hall

Fig. 3.22. Market Hall Interior Study (Above) Development sketch exploring the multistory market hall above the train platforms. Fig. 3.24. Market Hall Stress Visualisation (Right) Fig. 3.23. Market Hall Rationalised Structural System (Opposite Left) Compression members emanate from the footings, creating interdependancies within the structure.

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Fig. 3.25. Market Hall Structure Exploded Isometric (Opposite Right) A lower branching arched structure simultaneously covers the main market floor whilst created space for retailers above. A second set of arches create a top level dining area, branching down to brace the system.

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Fig. 3.26. Typical Structure Interior Study (Above)

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3.3 Composition The splicing of elements is dictated by the need to limit component size to a maximum transportable dimension to a the given site. The design studio project is London so the components are required to fit within a vehicle of dimensions 16.5x 2.55x 3 meters. Although the structure would be spliced according to transportation requirements (Fig. 3.30), each component is constructed from a series of sheets requiring prior fabrication (Fig. 3.29). The hierarchy of elements is as follows:

Primary ‘trunk’ element of the lowest bending radius and greatest structural load constructed from either steam bent or larger lamella. Secondary ‘bough’ assemblies are fabricated and fixed to the central trunk Tertiary ‘branches’ of the tightest bending radius are laminated from veneer sheets and serve to describe the final structure and create a homogeneous connection between the trunk and boughs.

Fig. 3.27. Node and frame connections. (Top) The structure can be understoof as a series of lines and points in order to establish flat areas for machining. Fig. 3.28. Lamella Hierarchy. (Centre) The trunk, bough and branch pieces create a set of homogeneous connections. Fig. 3.29. 3-dimensional rationalisation. (Right) Each homogeneous connection is constructed as a series of 3-points splines, and can be understood as bent around an axis in space.

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Fig. 3.30. Typical Homogeneous and Scarf Connection (Opposite) The flat area can be machined easily as sufficient flat areas allow for the used of a repeated proccess.

Scarf Joint

Laminated Veneer Lumber

50mm Glue Laminated Timber

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3.4. Component Frabrication Form Fabrication A technical challenge in the construction of curved or doubly curved timber structures is the requirement for forms around which the wood can bend. This thesis explores the construction of an assembly which allows for two methods of achieving a desired curvature and double curvature. The first builds of the previous research within the thesis by milling forms from foam based on NURBS surfaces extracted from 3D model on which veneer layups can be pressed within a vacuum bag. The second method investigates activating the natural adhesive properties of the lignin within the timber to allow the material to bend after steaming. Within the steam bending process, forms were constructed to acheive single and double curvature (Fig. 3.31). Each form for the pressing of veneers was to be reoriented for the milling process (Fig. 3.33), to avoid undercuts and be effectively milled from Polyurethane foam (Fig. 3.32). Due to limitations of the machine, some of the pieces were segmented and glued together . The forms were slightly oversized by ten percent in the length and width to account for the trimming back and finishing of laminated layup.

Fig. 3.31. Steam Bending Jigs (Top) The steam bending attempted to allow the material to define the curvature naturally based on the grain within the particular piece of wood. Fig. 3.32. CNC Toolpaths from Polyurethane Foam. (Right) Roughing and smoothing paths were carried out extremely quickly due to the soft and light material. Fig. 3.33. Bending Assembly (Opposite) A colour coded drawing indicating the proposed fabrication technique for each curved and double curved element in the assembly.

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3.4 Pressing The pieces being pressed to the form were grouped in layups of 4 and 8 sheets and pressed around the former in a â&#x20AC;&#x2DC;dry runâ&#x20AC;&#x2122; to establish how much free plastic within the bag would be required and to what extent the piece might warp under the pressure. Layers of PVA glue were applied to the sheets, with tape providing the first fix in order to position the form and veneers in the vacuum bag (Fig. 3.34) (Fig. 3.35). In order to achieve close to uniform pressure, the nozzle was positioned at the centre of the top veneer. For the tightest radii, it was necessary to place a sacrificial sheet of veneer in the crossgrain direction to prevent breakout within the top veneer. Test pieces displayed some defects in the edge conditions (Fig. 3.36) and nominal deviations from the original form (Fig. 3.37).

Fig. 3.34. Layup under Vacuum Bag Pressure (Top) The vacuum bag was central to the proccess, in order to provide sufficent pressure to the complex geometry. Fig. 3.35. Form and Lamella Arrangement (Centre) Several pieces were pressed in unison, saving time against a positive-negative mould or a series of clamps. Fig. 3.36. Double Curve Lamination Tests (Right)Series of tests to understand the fidelity to the orignal foam forms. Noticeable defects include a wave along the edge where the sheets have entended beyond the form.

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Fig. 3.37. Foam and Layups (Opposite) Selection of pieces used in the final assembly. Some deviation from the form occured, however the thin pieces remained reasonably malleable after lamination.

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3.4 Bending The vertical growth pattern of the tree has meant that the fibrous cellulose and hemicellulose are bound together by lignin. Like many rigid materials, timber can respond to bending and return to its former shape up to a point. A unique property of timber is the propensity to withstand bending. When timber is steamed, the lignin becomes liquid and the fibres are free to move past each other. Once the timber has cooled down, the lignin sets hard and the piece remains in the newly bent form. During the process of bending, tension and compression forces are visibly evident (Peck, 1957, p.10). The fibres toward the outside of the bend are being pulled apart and this is where break-out is likely to occur, whilst the fibres on the inside of the bend are being compressed, sometimes made visible by a wave in the surface. If the timber is released from the mould when wet and heated, the piece is likely to return to the former shape, and if there is not sufficient pressure applied to the ends of the piece, there is likely to be failure in the convex side of the piece.

Dual pipes Air-tight Steam Tube Electronic Steamers

Within the prototype, the ‘trunk’ and ‘bough’ elements were laminated from steam bent pieces in order to activate the lignin within the beech strips (Fig. 3.39). Issues associated were spring back difficulty in assuming a double curvature(Fig. 3.41) and kinks where the curvature was not completely described (Fig. 3.40). It is important to select stock that is well suited to bending in the proposed orientation. Straight grained wood is most desirable for steam bending, as the tree rings are free to slide across each other. The wood is far less likely to achieve a successful bend if the grain is perpendicular to the surface of the form (Fig. 3.38). Following the rule of thumb of one-minute-per-inch of material depth, the pieces were taken out from the steamer and laid along metal strips, sandwiched between two fixed blocks to apply compression at either end. During the bend it becomes visibly evident that the wood is in compression and tension as a tight bend will show buckling on the inside of the bend and break-out may occur on the outside.

Power Outlet

Smooth curve defined by form

Kink in free form bend

Fig. 3.38. Bending Axis comparison (Above) Just like a deck of cards, a far greater radius is achieved when bending perpendicular as opposed to tangential to the grain. Fig. 3.39. Steam Bending Setup (Centre) An outdoor setup of two electronic steamers ensured one could be refilled as the other remained active. Fig. 3.40. Bending Form Comparison (Right) Defining just the entry meant a kink was visible in the piece whilst a more gradual curve is acheived when fully defined. Fig. 3.41. Springback Analysis (Opposite) The form was iterated through an understanding developed of the spingback specific to the material stock, as a second jig was overly curved to compensate. 120

Entry and exit orientations defined

Entire Curvature Defined

Acheived angle

Target Angle Proposed Corrective Angle

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3.4 Lamination When a bolted connection is introduced to a structural timber element, the fibres are damaged and the strength is compromised. This means element is often oversized to compensate for the material lost to the connection. Gluing timber components together directly enables the form and cross-section of the timber to be preserved and allows the two-dimensional adhesive joints to transfer the forces uniformly over a large area ( Jeska et al., 2014, p. 23). The assembly of curved and double curved timber pieces is reliant on a sound lamination process. Typically for larger Glulam structure a space filling glue such as Melamine resin, Polyurethane, Resorcinol resin and epoxy resin are specified (Pascha, 2014b, p. 48). Working at a scale of 1:5 the component produced for the thesis required PVA glue with pressure applied from clamps and MDF. To laminate the steam bent batons of the ‘Trunk’, a series of clamps were used to apply pressure at roughly 5 cm intervals (Fig. 3.43). Although the two pieces were subject to varying levels of spring back, the lamination process brought the elements together and enclosed any minor break out. The system is such that all laminated components meet at a flat junction, in so doing they can be glued and clamped together more readily (Fig. 3.42) (Fig. 3.44).

Fig. 3.42. ‘Bough’ and ‘Branch’ Lamination (Centre) Creating a homogeneous connection between the steam bent curved and laminated double courved pieces. Fig. 3.43. ‘Trunk’ Lamination (Right) Two pieces are require to achieve the depth of the component as much break-out and buckling would have likely occured in a single piece. Fig. 3.44. Full Lamination Assembly (Opposite) Fewer clamps were require than typical glulam system as sheet material was used to evenly distribute the pressure across the surface of the joining pieces.

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3.4

Cut 1 Cut 2

Assembly

workpiece

A Plait de Jupiter scarf joint is used to join components within the assembly as the wedges allow for dry and safe construction and disassembly (Fig. 3.47 - Fig 3.51), the only disadvantage is the great effort required to produce it (Zwerger, 2015, p. 236). Jig

With emerging tools for fabrication, it is now possible to produce scarf joints without the laborious efforts of the traditional methods. The Plait de Jupiter scarf (stop-splayed & tabled scarf with key) was selected based on excellent performance in both tension and compression in either axis (Hirst et al., 2008, p. 5). Physical tests also confirmed it was a more convenient joint to fabricate than The Face Halved with Blade Abutments (Fig. 3.46). A jig was used to ensure the same profile on both pieces. Wedges were hammered into a gap in the joint. This downward force is translated to a direction perpendicular to the wedgeâ&#x20AC;&#x2122;s inclined plane, pushing the pieces closer together (Fig. 3.45). This process remains still more time intensive than a plate connection, so a further advancement of the process would have been to introduce fully milled joints like those produced by many automated systems adapted to cut at the position of the doubly curved components.

Fig. 3.45. Scarf Cutting Strategy 3 cuts are made with the use of a jig to raise the piece allowing for the curvature. Fig. 3.46. Scarf joint Tests The Face Halved with Blade Abutments and Plait de Jupiter scarf tests. Fig. 3.47. Sarf Joint Detail Wedge slightly proud of the surface, to be knocked in to further tension the joint. Fig. 3.48. Branching Components Two branching elements and wedges. 124

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3.5. Section Conclusion

The final section synthesises knowledge gained in the literature review of section one and the primary material investigations of section two. An understanding of the historic applications of timber has helped in the development of a viable construction system, whilst the earlier experiments established a library of tools and techniques to develop the design proposal. Specifically the final section documented the design development of a resource efficient long-span timber structure with homogeneous and wood-to-wood connections. A unique expression was given to the structure in the synthesis of a material distribution strategy aided by structural visualisation in Karamba 3D and insights gained from observing the material behaviour of the Beech. A level of complexity was relinquished from the previous experiments as some techniques proved difficult with modern methods of mould making. There were, however, a number of new characteristics of material behaviour evident in the scaling of the techniques evident in the steam bending and laminations process which lent character to the final piece.

Fig. 3.49. Assembled Building fragment (Opposite) 1:5 model showing the fullly assembled homogeneous â&#x20AC;&#x2DC;forksâ&#x20AC;&#x2122; by the Plait de Jupiter Scarf joint Fig. 3.50. Bough and Branch Component (Overleaf)

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Fig. 3.51. Trunk and Bough Component (Overleaf)

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Conclusion

The thesis is intended to advance the field of research in the design and construction of long-span timber structures. The three sections of Topic, Abstraction and Synthesis allow for the gathering of knowledge through a comprehensive literature review, the generation of themes and work-flows for primary investigation through scale prototypes and ultimately the proposal of a viable system for construction. Upon reflection there have been five key themes of significant interest in the development of the long-span timber construction system (Fig. 3.52).

The most central theme of the study is the understanding that timber construction always requires knowledge concerning material properties. Felling, cutting, laminating and machining all demand a different understanding of the opportunities and limitations imposed by the chemical, biological and mechanical properties of the natural material. A conclusion can be made however that it is most fruitful to embrace rather than ignore these properties; this knowledge has been the source of great frustration as well as satisfaction.

In building up a knowledge and understanding of convention, the system is lent greater validity. A comparison of the hollow tube system to the final prototype shows that the latter system contributes to a tradition of timber construction, engaging with and advancing conventions in component fabrication and assembly. An understanding of conventions in timber construction reveals also that buildings are not simply a product of technological advancement but that they reflect and address human need. In this way the introduction of the platform frame can be seen not as a â&#x20AC;&#x2DC;dumbing downâ&#x20AC;&#x2122; of timber but rather an interesting intersection between technology and human need whereby population growth and industrialisation marked an important development in the history of engineered timber. This notion can be more widely expanded to recognise that the ability for timber to sequester carbon makes it a crucial tool in the construction of buildings. The thesis has been an excellent vehicle to gain knowledge of emerging methods of fabrication in timber construction. It can be concluded that advancements in tools are to be leveraged in the advancement of a construction system. It has also been necessary to consider advancements in the jigs and moulds required to process the material. These include MDF forms for steam bending, 3D printed Surface Forms, CNC milled foam moulds and to the jigs required for wood to wood joints. Advancements in analysis have become of increasing importance for the designer as tools such those within the Grasshopper plug-in suite mean complex simulations can be undertake by the individual. It can be concluded from the findings, however, that the tools used could in no way replace the decision-making skills of the designer, but merely provide information from which to progress and iterate. In the most advanced studies of the thesis, knowledge gained in the growth, structure and processes of the tree itself has been useful, with a key finding being that a shift from mechanical to homogeneous means of connection in timber construction could lead to the eradication of metals and composites and in turn major reductions in material use, both contributing to unique tectonic qualities. 130

Fig. 3.52. Five Key Themes (Overleaf) Diagram distilling the key interdependent themes within the thesis. Recognising that a novel system should recognise innovations of the past whilst the material properties can be understood with respect to fabrication, digital analysis, current methods of construction and the tree itself. Fig. 3.53. Collated Prototypes (P. 131)

Material Properties

Convention

Analysis

The Tree

Fabrication

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â&#x20AC;&#x2DC;There are a million patient, watchful lives still for a tree, all over the world, in bedrooms, in ships, lining rooms where men and women sit after tea... It is full of peaceful thoughts, happy thoughts, this treeâ&#x20AC;&#x2122;

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(Woolf, 1917, p. 30)

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Bibliography Books Aalto, A., Schildt, G., (1998). Alvar Aalto in his own words/ edited and annotated by Goran Schildt. Rizzolli, New York.

Peck, E., (1957). Bending Solid Wood to Form. US Forest Service.

Bramwell, M., (1982). The International Book of Wood. Artists House, London.

Penn, R., (2015). The man who made things out of Trees. Penguin Random House, UK.

Brino, G., (2005). Carlo Mollino: Architecture as autobiography. Thames & Hudson, UK.

Piano, R., Frampton, K., (2016). Renzo Piano, The Complete Logbook. Thames & Hudson.

Brunskill, R., (1985). Timber building in Britain. Cassell, London.

Reinprecht, L., (2016.) Wood Deterioration, Protection and Maintenance. John Wiley & Sons Incorporated, Chichester.

Buri, H.U., Weinand, Y., (2011). The Tectonics of Timber Architecture in the Digital Age. Prestel Verlag, Munich.

Rice, P., (1992). Exploring Materials: The work of Peter Rice: royal gold medallist, 1992. RIBA Gallery, London.

Engel, H., (1981). Structure Systems. Van Nostrand Reinhold, New York.

Stevens, J.R., (1949). An account of the construction, and embellishment of old time ships. John R. Stevens, Toronto.

Falconer, J., Rivas, B., (2013). De Havilland Mosquito Manual: An insight into developing, flying, servicing and restoring Britain’s legendary “Wooden Wonder” fighterbomber. J H Haynes & Co, UK.

Sturt, G., (1923). The Wheelwright’s Shop. Cambridge University Press, Cambridge.

Frampton, K., (1995). Studies in Tectonic Culture. The Poetics of Construction in Nineteenth and Twentieth Century Architecture. MIT, Cambridge, MA. Greenhill, B., (1974). The Evolution of the Wooden Ship. The Blackburn Press, New Jersey.

Welsh, P.C., (2008). Woodworking Tools 1600-1900. Project Gutenberg, London. Wilk, C., (2017). Plywood: A Material Story. Thames & Hudson, UK. Zwerger, K., (2015). Wood and Wood Joints. Birkhäuser, Basel.

Hunt, T., (1997). Structures Notebook. Architectural Press, Oxford. Jeska, S., Hascher, R., Pascha, K.S., (2014.) Emergent Timber Technologies: Materials., Structures, Engineering, Projects. Birkhäuser, Basel. Lindholm, D., Roggenkamp, W., (1969). Stave Churches in Norway: Dragon Myth and Christianity in Old Norweigian Architecture. Rudolf Steiner, London. Lonsdale, D., (2000). Hazards from Tree: A general guide. Forestry Commission Practice Guide. MacGregor, D., (1972). The Tea Clipper: a account of the China tea trade and some of the British sailing ships engaged in it from 1849 to 1869. Conway Maritime Press, London. Ngo, D., Pfeiffer, E., (2003). Bent Ply. Princeton Architectural Press, New York. Organschi, A., Waugh, A., (2014). Timber in the City. ORO Editions, San Franscisco. Otto, F., Rasch, B., (2006). Towards and Architecture of the Minimal, 5th ed. Deutcher Wekbund, Bayern. 134

Book Sections Green, D., Winandy, J., Kretschmann, D., (1999). ‘Mechanical Properties of Wood’, in: Wood HandbookWood as an Engineering Material. US Forest Service, Madison, WI. Heidegger, M., (1971). ‘On the Origin of the Work of Art’, in: Poetry, Language and Thought. Harper & Row, New York. Mayne, T., (2012). ‘Shift 2D to 3D’, in: Digital Workflows in Architecture: Design-Assembly_Industry. Birkhäuser, Basel, pp. 202–205. Pascha, K.S., (2014a). ‘Developments in timber construction materials’, in: Emergent Timber Technologies. Birkhäuser, Basel. Pascha, K.S., (2014b). ‘Historic design typologies’, in: Emergent Timber Technologies. Birkhäuser, Basel, pp. 8–13.

Scheuer, F., (2012). ‘Digital Craftsmanship: From thinking to modelling to building’, in: Digital Workflows in Architecture. Birkhäuser, Basel, pp. 110–131. Tamke, M., (2013). CITA ‘Working for and with material performance’, in: Danish Design Week 11. CITA, Copenhagen. Woolf, V., (1917). ‘The Mark on the Wall’, in: Two Stories. The Hogarth Press, Richmond, pp. 19–30.

Conference Papers Burger, N., Muller, A., Natterer, J., 2000. The “EXPO-roof ” in Hanover - A new dimension for ripped shells in timber. Presented at the World Conference on Timber Engineering. Hirst, E., Brett, A., Thomson, A., 2008. The Structural Performance of Traditional Oak Tension and Scarf Joints. Presented at the 10th World Conference on Timber Engineering, Miyazaki, Japan. Poinet, P., 2016. Multi-Scalar Modelling for Free-form Timber Structures. Presented at the IASS Annual Symposium, Centre for Information Technology and Architecture, Tokyo.

Journal Articles

Schindler, C., 2007. Information-Tool-Technology: Contemporary digital fabrication as part of a continuous development of process technology as illustrated with the example of timber construction. Presented at the ACADIA Conference 2007, Nova Scotia.

Ando, M., Fleming, P.H., (2018). A Study of Alvar Aalto’s Wood Reliefs for Furniture and Architectural Design. https://doi.org/10.1093/jdh/epy042 Bhooshan, S., (2017). Collaborative Design: Combining Computer-Aided Geometry Design and Building Information Modelling. Architectural Design 87, 82–89. Harris, R., Romer, J., Kelly, O., Johnson, S., (2003). Design and construction of the Downland Gridshell. Building Research & Information 31, 427–454. Isohauta, T., (2013). The Diversity of timber in Alvar Aalto’s architecture: forests, shelter and safety. Architecture Research Quarterly 17, 269–280. Louw, H., (1992). The Mechanisation of Architectural Woodwork in Britain from the Late-Eighteenth to theEarly Twentieth Century, and its Practical, Social and Aesthetic Implications. Part I: ThePeriod c. 1790 to c. 1860. Construction History 8, 21–54. Sheurer, F., (2010). Materialising Complexity. Architectural Design 80, 86–93. Thistleton, A., (2018). ‘Architecture is political; it’s time for the timber revolution.’ Architects’ Journal. Özden, S., Slater, D., Ennos, R., (2017). Fracture properties of green wood formed within the forks of hazel (Corylus avellana L.). Trees 31, 903–917. https://doi.org/10.1007/ s00468-016-1516-0

Reports Abergel, T., Dean, B., Dulac, J., 2017. Global Status Report 2017. International Energy Agency, United Nations Environment Programme. STA, 2018. Timber Frame Structures - Platform frame construction. UKGBC, 2015. Tackling embodied carbon in buildings. UK Green Building Council for The Crown Estate.

Presentations Aalto, A., 1935. Rationalism and Man. Menges, A., 2012. Material Computation. Schindler, C., 2011. An architectural periodisation model with criteria of production technology, as illustrated with the example of timber construction.

135

List of Figures Section 1. Topic: Timber Frame Evolution 1.1. Introduction Fig. 1.1. Final Prototype Detail (Author’s Photgraph) Fig. 1.1. No. 3 Slip (Ibid.)

1.2.

5 11

Wood: A Definition

Fig. 1.2. Molecular Structure of Wood (Diagram by Author after Reinprecht, 2016, p. 9) Fig. 1.3. Anatomical Structure of Wood (Ibid.) Fig. 1.4. Geometric Structure of Wood (Ibid.) Fig. 1.5. Growth Patterns (Ibid.) Fig. 1.6. Hardwood Composition (Diagram by Author after Bramwell et al. 1982, p. 10) Fig. 1.7. Timber Coordinate System (Diagram by Author after Green et al., 1999, p. 2 ) Fig. 1.8. Ash Sapling Anatomy (Diagram by Author after Bramwell et al. 1982, p12)

12 12 12 14 14 14 14

1.3. Hand Fig. 1.9. Traditional methods of marking (Diagram by Author after Brunskill, 1985, p108) Fig. 1.10. Carpenter’s Marks in Cruck Barn, UK. (Photograph by T. Hughes for Historic England: [https://historicengland.org.uk/whats-new/ features/discovering-witches-marks/types-ofmarks/]) Fig. 1.11. 6 Simple Machines. (Drawing by J.Mills for The Realities of Modern Science (1919), p. 15, Fig. 3) Fig. 1.12. Hand Tools. (Drawing by T. Martin for Woodworking Hand Tool 1600-1900 (2008), Fig. 7) Fig. 1.13. Concise wooden ship evolution. (Drawn by Author after Greenhill, 1974, p. 5) Fig. 1.14. The Oseberg Viking Ship. (Drawn by Author after Viking Ship Museum, Oslo:[https://commons.wikimedia.org/wiki/ File:Krummtra.JPG]) Fig. 1.15. Bent Timbers of the Clipper (Drawn by Author after Bramwell et. al 1985, p20) 136

16 16

17 17 18 18

Fig. 1.16. Clipper Assembly (Drawn by Author after ‘The Doric Columns’ :http://mcjazz.f2s.com/ClipperShipPlans. htm]) Fig. 1.17. Clipper Bow Construction (Ibid.) Fig. 1.18. Clipper Hull Section & Details (Ibid.) Fig. 1.19. Technology Transfer: Ship to Stave church. (Drawings by W.Roggenkamp for Lindholm, D., Roggenkamp, W., 1969. , p15) Fig. 1.20. Borgund Stave Church Worm’ Eye Isometric (Drawing by Author after Jorgen H. Jensenius for Stavkirkke: [https://www.stavkirke.info/ english.html]) Fig. 1.21. Timber Frame Evolution in Britain (Drawing by Author after Brawmell et al., 1982, p. 38) Fig. 1.22. Typical Cruck Frame System (Drawing by Author after Brunskill, 1985, p.50) Fig. 1.23. Lap Joints (Drawing by Author after Brunskill, 1985, p.60) Fig. 1.24. Splice Joints (Drawing by Author after Brunskill, 1985, p.61) Fig. 1.25. Barns of the UK (Drawings by Author after Ken:[http://www. greatbarns.org.uk/])

21 22 24 24

26 26 28 29 30

1.4. Machine Fig. 1.26. Naysmyths’ ‘Machine Tool Technologist (Drawing by J. Naysmyth, 1841: [https://commons.wikimedia.org/wiki/ File:Nasmyth_Lathe.png] Fig. 1.27. Water Powered Saw. Villard de Honnecourt (Image from the Portfolio of Villard de Honnecourt: [http://classes.bnf.fr/villard/ feuillet/]) Fig. 1.28. Balloon Frame (Drawing by Author after STA, 2018, p. 2) Fig. 1.29. Platform Frame (Ibid.) Fig. 1.30. Rotary Cut Veneer (Drawing by Author after Ngo, D., Pfeiffer, E., 2003, p15) Fig. 1.31. Mosquito Assembly (Drawing by Author after Falconer and Rivas, 2013, p. 110 ) Fig. 1.32. Eames’ Splint (Drawing by Author) Fig. 1.33. Mosquito Construction (Drawing by Author after

33 33 34 34 34 36

Falconer and Rivas, 2013, p. 105 ) Fig. 1.34. Otto Hetzers first glue laminated member (Patent Drawing by Otto Hetzer , 1903: [http://www.otto-hetzer.de/bauwerke.html]) Fig. 1.35. Aalto’s Fan Leg Stool Patent No. 28191 (Patent No. 28191 by Alvar Aalto: [https:// www.prh.fi/stc/attachments/innogalleria/ nayttelytekstivihkonen.pdf ]) Fig. 1.36. Helsinki Fair Competition (Drawing by Alvar Aalto 1934 : https:// artsandculture.google.com/asset/exhibitionhall-messuhalli-helsinki-competitionproposal/uwHa3x5xc5CWzw]) Fig. 1.37. Mollino’s Vertibrae Table (Drawing by Author) Fig. 1.38. Pompidou Centre Gerberette Detail (Photograph by Author) Fig. 1.39. Pompidou Centre Gerberette Isometric (Drawing by Author) Fig. 1.40. Portcullis House Detail (Photograph by Hopkins Architects: [https:// www.hopkins.co.uk/projects/5/100/]) Fig. 1.41. Portcullis House Isometric Study (Drawing by Author) Fig. 1.42. IBM Travelling Pavilion Detail (Photograph Renzo Piano Building Workshop:[http://www.rpbw.com/project/ ibm-travelling-pavilion]) Fig. 1.43. Parco de le Musica facade interior (Photograph Renzo Piano Building Workshop:[http://www.rpbw.com/project/ parco-della-musica-auditorium]) Fig. 1.44. Parco de le Musica milled lamination detail (Drawing by Author)

38 38

39 40 40 40 40 42

Fig. 1.50. Hannover Expo Pavilion Exterior (2002) 46 (Photograph Visit Hanover: [https://www. visit-hannover.com/nl/Beurs-economie/ Eersteklas-gastheer/Deutsche-Messe-AGExhibition-Grounds]) Fig. 1.51. Table and Shell Interface 46 (Photograph by Burger et al 2000, p4, fig.4) Fig. 1.52. Roof Shell Structure 46 (Drawing by Author after Burger et al, 2000, p.3) Fig. 1.53. Hannover Pavilion Nodes 46 (Drawing by Author after Burger et al. , 2000, p.5) Fig. 1.54. Numerical Manufacturing strategies for Timber construction 48 (Drawing by Author after Schindler, 2007, sec. 4) Fig. 1.55. The Rise 48 (Drawing by Author after Tamke, M, 2013, p.221) Fig. 1.56. Aggregated Lamination 48 (Drawing by Author )

1.5. Conclusion Fig. 1.57. Downland Gridshell Interior (Photograph by Author)

Section 2. Abstraction: Lamination Experiments

1.5. Information Fig. 1.45. Otto and the Prototype House 44 (AA Design and Make: [http:// designandmake.aaschool.ac.uk/project/ prototype-house/]) Fig. 1.46. Mannheim Gridshell Hanging Chain Model 44 (Photograph Frei Otto and the Development of Grishells: [https://www.researchgate. net/publication/283164806_Frei_Otto_ and_the_Development_of_Gridshells/ figures?lo=1]) Fig. 1.47. Mannheim Gridshell Connection Detail Model 44 (Photograph by Leihener, J : [http:// triangularlatticeroof.blogspot.com/]) Fig. 1.48. Downland Gridshell Pin Connection 44 (Drawing by Author) Fig. 1.49. Downland Gridshell Super Structure 44 (Drawing by Author)

2.1. Introduction Fig. 2.1. Lamination Experiment Series (Photograph by Author)

2.2.

Engineering Timber

Fig. 2.2. Wood Materials (Marra, 1972) 54 (Drawing by Marra 1977 in Schindler, 2009, p. 179, fig. 94) Fig. 2.3. Balancing Natural Properties and Manufacturing Potential 54 (Diagram by Author) Fig. 2.4. Engineered Timber Products Manufacturing Processes 54 (Diagram by Author) 137

2.3.

138

Lamination Experiments

Fig. 2.5. Mould Assembly (Drawing by Author) Fig. 2.6. Cutting Schedule (Drawing by Author) Fig. 2.7. Clamping Strategy (Drawing by Author) Fig. 2.8. Spliced Lamination Assembly (Drawing by Author) Fig. 2.9. Spliced Lamination (Photograph by Author)

Fig. 2.10. Reviving the Cruck (Drawing by Author) Fig. 2.11. Cutting Schedule (Drawing by Author) Fig. 2.12. Mould Assembly Fig. 2.13. Continuous Cruck Lamination Assembly (Drawing by Author) Fig. 2.14. Continuous Cruck (Photograph by Author)

Fig. 2.15. Veneer Species (Drawing by Author) Fig. 2.16. Cutting Schedule (Drawing by Author) Fig. 2.17. Strip Schedule Automation (Drawing by Author) Fig. 2.18. Additive Lamination Assembly (Drawing by Author) Fig. 2.19. Additive Lamination (Photograph by Author)

Fig. 2.20. Shell bending radii (Drawing by Author) Fig. 2.21. Shell Shrink Action (Photograph by Author) Fig. 2.22. Shell Pressing (Photograph by Author) Fig. 2.23. Shell Radium Test (Photograph by Author) Fig. 2.24. Cross-laminated Shells Arrangement (Photograph by Author) Fig. 2.25. Cross-laminated Shell Lamination Assembly (Drawing by Author) Fig. 2.26. Cross-laminated Shell (Photograph by Author)

Fig. 2.27. 3D printed Form Assembly (Drawing by Author) Fig. 2.28. Radius Range (Drawing by Author)

56 56 58 58

60 60 62 62

64 64 66 66

68 68 68 68 70 70

Fig. 2.29. Raw Sheet Layup 72 (Drawing by Author) Fig. 2.30. Cross-laminated Surface Lamination Assembly 74 (Drawing by Author) Fig. 2.31. Cross-laminated Surface 74 (Photograph by Author) Fig. 2.32. Stress Visualisation for column and slab system (Drawing by Author) Fig. 2.33. Canopy Utilisation. (Drawing by Author) Fig. 2.34. CNC Mould (Photograph by Author) Fig. 2.35. Mould Toolpaths (Drawing by Author) Fig. 2.36. Seamless Column Lamination Assembly (Drawing by Author) Fig. 2.37. Seamless Column (Photograph by Author)

Fig. 2.38. Tube Profile (Drawing by Author) Fig. 2.39. Potential Hollow Tube Application (Drawings by Author) Fig. 2.40. Vaccum Bag Press (Photograph by Author) Fig. 2.41. Cross-laminated Tube Lamination Assembly (Drawing by Author) Fig. 2.42. Cross-laminated Tube (Photograph by Author)

Fig. 2.43. Forking Grains Comparison (Drawing by Author after Lonsdale et al, 2000, p6) Fig. 2.44. Collapsible Mould Assembly (Photograph by Author) Fig. 2.45. Veneer Application (Photograph by Author) Fig. 2.46. Collapsible Mould (Photograph by Author) Fig. 2.47. Bifurcating Tube Lamination Assembly (Drawing by Author) Fig. 2.48. Bifurcating Tube (Photograph by Author)

77 77 78 78

80 80 82 82

84 84 84 86 86

2.3. Conclusion Fig. 2.49. Lamination Experiment Series II (Photograph by Author)

Section 3. Synthesis: Design Studio Project 3.1. Introduction Fig. 3.1. East Elevation (Drawing by Author)

3.2.

Project Description

Fig. 3.2. Market Hall Section (Drawing by Author) Fig. 3.3. Building Overview (Drawing by Author) Fig. 3.4. Wintergarden Interior Study (Drawing by Author)

3.3.

92 92 92

Design Development

Fig. 3.5. Minimum and Maximum Module Spans (Drawing by Author) Fig. 3.6. Superstructure (Drawing by Author) Fig. 3.7. Typical Structural Bay Assembly (Drawing by Author) Fig. 3.8. Profile Differentiation (Drawing by Author after Bramwell et. al. P. 15) Fig. 3.9. Good and Bad Forks (Drawing by Author after Lonsdale et al, 2000, p6) Fig. 3.10. Tension and Compression within the log (Ibid.) Fig. 3.11. Tension and Compression within the tree (Ibid.) Fig. 3.12. Branching Studies (Drawing by Author) Fig. 3.13. Physical Branching Study with 3D Veneer (Drawing by Author) Fig. 3.14. Stress Line Visualisation (Drawing by Author) Fig. 3.15. Stress Line Rationalisation (Drawing by Author) Fig. 3.16. Typical and Cantilevered Stress Lines (Drawing by Author) Fig. 3.17. Roof Structure Types (Drawing by Author) Fig. 3.18. Typical Roof Structural Bay (Drawing by Author) Fig. 3.19. Typical Bay Graph Map (Drawing by Author) Fig. 3.20. Typical Roof Structural Bay (Drawing by Author)

Fig. 3.21. Modelling Sequence (Drawing by Author) Fig. 3.22. Market Hall Interior Study (Drawing by Author) Fig. 3.24. Market Hall Stress Visualisation (Drawing by Author) Fig. 3.23. Market Hall Structural System (Drawing by Author) Fig. 3.25. Market Hall Structure Isometric (Drawing by Author) Fig. 3.26. Typical Structure Interior Study (Drawing by Author) Fig. 3.27. Node and frame connections. (Drawing by Author) Fig. 3.28. Lamella Hierarchy. (Drawing by Author) Fig. 3.29. 3-dimensional rationalisation. (Drawing by Author) Fig. 3.30. Homogeneous and Scarf Connection (Drawing by Author)

106 108 108 108 108 110 112 112 112 112

94 94 94 96 96 96 96 98 98 100 102 102 104 104 106 106

3.4.

Component Fabrication

Fig. 3.31. Steam Bending Jigs (Photograph by Author) Fig. 3.32. CNC Toolpaths from PU Foam (Drawing by Author) Fig. 3.33. Bending Assembly (Drawing by Author) Fig. 3.34. Layup under Vacuum Bag Pressure (Photograph by Author) Fig. 3.35. Form and Lamella Arrangement (Photograph by Author) Fig. 3.36. Double Curve Lamination Tests (Photograph by Author) Fig. 3.37. Foam and Layups (Photograph by Author) Fig. 3.38. Bending Axis comparison (Photograph by Author) Fig. 3.39. Steam Bending Setup (Photograph by Author) Fig. 3.40. Bending Form Comparison (Photograph by Author) Fig. 3.41. Springback Analysis (Photograph by Author) Fig. 3.42. ‘Bough’ and ‘Branch’ Lamination (Photograph by Author) Fig. 3.43. ‘Trunk’ Lamination (Photograph by Author) Fig. 3.44. Full Lamination Assembly (Photograph by Author) Fig. 3.45. Scarf Cutting Strategy (Drawing by Author) Fig. 3.46. Scarf joint Tests (Photograph by Author)

114 114 114 116 116 116 116 118 118 118 118 120 120 120 122 122 139

Fig. 3.47. Sarf Joint Detail (Photograph by Author) Fig. 3.48. Branching Components (Photograph by Author) Fig. 3.49. Assembled Building fragment (Photograph by Author) Fig. 3.50. Bough and Branch Component (Photograph by Author) Fig. 3.51. Trunk and Bough Component (Photograph by Author)

122 122 124 124 124

3.5. Conclusion Fig. 3.52. Five Key Themes (Diagram by Author) Fig. 3.53. Collated Prototypes (Photograph by Author)

130

Appendix: Additional Drawings

Fig. 4.1. Site Plan (Drawing by Author) Fig. 4.2. Site Elevation (Drawing by Author) Fig. 4.3. Euston Road Approach (Drawing by Author) Fig. 4.4. Euston Road Approach (Drawing by Author) Fig. 4.5. Entry Fragment Isometric (Drawing by Author) Fig. 4.6. Eversholt Street Entry (Drawing by Author) Fig. 4.7. Typical Platform Transition (Drawing by Author) Fig. 4.8. Wintergarden Fragment (Drawing by Author) Fig. 4.8. Wintergarden Section (Drawing by Author) Fig. 4.10. Market Hall Section (Drawing by Author)

140

128

139 139 140 140 142 144 146 148 150 152

Sectionâ&#x20AC;&#x201A;4. Appendix Additional Drawings

Fig. 4.1.

Site Plan1:2000 at A2

Fig. 4.2.

Elevation 1:2000 @ A2 141

Fig. 4.3.

Euston Road Approach (Top)

Fig. 4.4.

Site Section (Above)

142

143

Fig. 4.5.

Entry Fragment Isometric (Above)

144

145

Fig. 4.6.

Eversholt Street Entry (Above)

146

147

Fig. 4.7.

Typical Platform Transition (Above)

148

149

Fig. 4.8.

Wintergarden Fragment (Above)

150

151

Fig. 4.9.

Wintergarden Section (Above)

152

Fig. 4.10. Market Hall Section (Above) 153