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Lightweight Structures for Remote Areas Lightweight Structures for Remote Areas Jessica Bak A thesis submitted for the degree of Doctor of Philosophy University of Bath Department of Architecture and Civil Engineering December 2015 COPYRIGHT Attention is drawn to the fact that copyright of this thesis rests with the author. A copy of this thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that they must not copy it or use material from it except as permitted by law or with the consent of the author. This thesis may be made available for consultation within the University Library and may be photocopied or lent to other libraries for the purposes of consultation. Jessica Bak This thesis is dedicated to my husband Andreas and daughter Isabel. i Acknowledgements I firstly want to thank to the Chilean Council for Science and Technology (CONICYT) for providing me with this opportunity by funding my MPhil and PhD studies at the University of Bath. My sincerest gratitude goes to my supervisor, Dr. Paul Shepherd, whose knowl- edge, creativity and support has been essential for the fulfillment of this endeavour. I am truly honoured to have completed this research under Dr. Shepherd’s supervision and have been part of the Digital Architectonics Research Group. This thesis would have not been possible without the invaluable advice and uncondi- tional support of Andreas Bak, from Søren Jensen’s Computational Design Group. I certainly cannot not express my gratitude for the help received at different stages of my research. I also want to thank my second supervisor, Professor Paul Richens, for providing me with enlightening advice, particularly during the early stages of my studies, as well as my examiners, Dr. Chris Williams and Professor Andrew Ballantyne, for making my Viva such an enjoyable experience. Special thanks goes to Dr. Francisco Fernandoy for his guidance regarding antarctic subjects; as well as Gordon Dolbear and Aske Birkelund for their contributions to the formatting and post-production of this thesis. iii Abstract The Antarctic built environment is characterised for its particular occu- pational regimen and includes whole-year stations, small-scale seasonal station and refuges, and temporary field camps. In recent years, Antarctic construction has begun to be considered of interest for the architectural and engineering communities, and interesting efforts have been made to provide solutions for spanning building, energy efficiency and improvements in indoor habitability. A fascinating array of lightweight constructions can be identified, whose contribution has not, until now, been fully documented and acknowledged. They represent remarkable examples of smart use of structural efficiency and minimal impact strategies enduring one of the harshest environments. This research is design-led and is motivated by the extension of the use of lightweight structures in remote fragile areas. The research validates the concept of polar lightweight design through a sound narrative describing the history and potential of this type of construction. For this, this research looks at the case of the Antarctic built environment. Furthermore, this research proposes that extension in the use lightweight construction could offer a sustainable solution for the predicted increase in the number of settlements being established in Antarctica. Knowledge and solutions achieved in this context can also be applied in other less demanding and fragile scenarios. In this regard, advanced computational design tools have been extensively validated for the realisation of structural surfaces of high geometrical complex- ity. Parametric design tools, are of particular interest to this research, as they allow the optimisation of a structure, either as a whole, or via its physical components. This research proposes that such tools can be employed for the development of Polar lightweight systems of larger scale and more complex configurations than currently seen. The first part is dedicated to the documentation and systematic character- isation of the vernacular Subantarctic and Antarctic lightweight constructions as structural systems. In the second part, the integration of polar constraints in the design of a generic lightweight structural system using parametric design tools is developed, in order to demonstrate the potential of this field for the creation of novel design methods and solutions. The particular case of a new medium-scale seasonal station is used as a case-study. v CONTENTS Contents Preface 1 1 Context and Research Aim 7 1.1 Introduction . 7 1.2 Occupation at the Antarctic region . 8 1.3 Overview of the Antarctic Built Environment . 12 1.4 Current Scenario and Perspectives for New Construction in Antarc- tica . 18 1.5 Design Brief for an Antarctic Seasonal Station . 20 1.5.1 Scope . 20 1.5.2 Site Conditions . 21 1.5.3 Environmental Conditions . 22 1.5.4 Logistics Conditions . 22 1.5.5 Overall Requirements . 23 1.6 Conclusions and Research Aim . 24 2 Characterisation of Antarctic and Subantarctic Lightweight Struc- tures 29 2.1 Introduction . 29 2.2 The Amundsen-Scott South Pole Station . 33 2.3 The Teniente Arturo Parodi Polar Station (EPTAP) . 38 2.4 The Shockwave Tent . 43 2.5 Subantarctic Indigenous dwellings . 47 2.5.1 The Kaweshkar (Alacalufe) Case . 49 2.5.2 The Yámana (Yaghan) Case . 51 2.5.3 The Selk’nam (Ona) Case. 53 2.5.4 The Tehuelche (Aoniken) Case . 56 2.6 Antarctic Portable Dwellings . 62 2.6.1 ‘In the Footsteps of Scott’ Expedition Tent . 63 2.6.2 Sastruggi Tent . 64 2.6.3 The Apple . 67 2.7 Conclusions . 69 vii CONTENTS 3 Design Criteria 75 3.1 Introduction . 75 3.2 Design Criteria . 76 3.3 Geometric Scheme . 77 3.3.1 Aggregation . 77 3.3.2 Adaptability . 80 3.4 Modularity versus Adaptability . 84 3.5 Design Scheme . 94 3.6 Design Method . 103 3.7 Conclusions . 103 4 Nodal Forces Method and Structural Components Design 105 4.1 Introduction . 105 4.2 Sensitivity Study for a Single Trussed Arch . 106 4.3 General Characterisation of the Main Structural Component . 108 4.4 Method . 109 4.5 Basic Material Properties . 114 4.5.1 Aluminium . 114 4.5.2 Composites . 115 4.5.3 Membranes . 118 4.6 Calculation of External Loads on a Single Trussed Arch. 118 4.6.1 Load Case 3: Wind Derived Loads as Nodal Forces . 119 4.6.2 Load Case 2. Snow Derived Load as Nodal Forces . 120 4.6.3 Calculation Method of Nodal Forces . 123 4.7 Interpretation of FE Model Results . 125 4.8 Variation Study . 129 4.8.1 Variation Study on the Arch’s Geometry . 129 4.8.2 Variation Study for Joint Shape . 137 4.8.3 Variation Study on the Number of Subdivisions . 140 4.8.4 Variation Study on the Arch’s Depth . 143 4.9 Conclusions . 144 5 Multi-Objective Design Process 147 5.1 Introduction . 147 5.2 Revision of pre-conditions for Sensitivity Study . 149 5.2.1 Material properties . 149 5.2.2 Pre-stress . 149 5.2.3 Standardisation of Span Values . 150 5.3 Sensitivity study . 151 5.3.1 Uniform Cross Section of Aluminium Joints . 152 viii CONTENTS 5.3.2 Variations of Rod Cross-Sections According to Span. 152 5.3.3 Variation of Arches’ Depth According to Span . 155 5.3.4 Grouping of Arches’ Attributes for Reduction of Internal Stresses ................................... 156 5.3.5 Geometry-based Method to reduce Pre-stress in Arches . 159 5.3.6 Uniform Load Condition of Arches’ Loaded Area . 165 5.4 Geometry-based Studies for the Reduction of Components . 173 5.4.1 Reduction of the Number of Nodes per Arch Group . 176 5.4.2 Reduction on the Number of Different Joints . 188 5.5 Parametric Model . 197 5.6 Conclusions . 203 6 Complementary Studies 207 6.1 Introduction . 207 6.2 Study for Variable Configurations . 207 6.3 Components Definition . 213 6.3.1 Carbon Fibre Bars . 213 6.3.2 Angled Bar Connections . 214 6.3.3 Aluminium Crosses . 215 6.3.4 Membrane Patterning and voids . 225 6.3.5 Rigid Boundary Arches . 228 6.3.6 Ending of tunnels . 233 6.3.7 Anchorages . 234 6.4 Assembly sequence . 234 6.5 Examples of Possible Applications for the Glacier Union Case . 243 6.6 Conclusions . 247 7 Conclusions 249 7.1 Introduction . 249 7.2 Contributions to Knowledge . 253 7.3 Theoretical implications . 254 7.4 Limitation of this study . 256 7.5 Future work . 258 7.6 Final comments . 260 Bibliography 261 Appendices A Prospects on a Formfinding Method using Surface Evolver and Parametric CAD Tools 273 ix LIST OF FIGURES A.1 The Surface Evolver . 273 A.2 Integrated geometry-based method using a Catenoid . 277 A.3 Testing Examples . 279 A.3.1 First Optimization of an Extruded Free-Form Curve . 282 A.3.2 Second Optimization of a Cylinder with a Free-Form Section 284 A.4 Further Work Using Surface Evolver . 286 A.4.1 Form-finding with oriented Boundaries . 286 A.4.2 Triple Periodic Minimal Surfaces . 286 A.4.3 Synclastic Surfaces Using other Energies . 287 A.5 Conclusions . 290 A.6 References . 290 B Calculations of Peak Velocity Pressure 293 C C-sharp Component for the Placement of Trussed Arches along a NURBS Curve 297 List of Figures 1.1 Magallanic Penguin at the Antarctic Peninsula. 8 1.2 Antarctic territorial claim. 9 1.3 Villa las Estrellas (Chile), one of two Antarctic settlements for a civilian community in Antarctica. 10 1.4 Map of Antarctic permanent and seasonal research stations’ locations. 10 1.5 Maximum summer capacity of Antarctica’s small scale stations. 12 1.6 Early Antarctic Construction. 14 1.7 Industrial looking constructions.
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