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Rasmus Holst s061860 M.Sc. Architectural Engineering think, script, build Architectural engineering through parametric modelling of intelligent systems in architecture. page 1 Resumé | This is a project about programming of intelligent systems by implementing information of physical behaviour, material-properties and connection design regarding advanced architectural projects. Focus is on utilisation of the geometric behaviour of elastic elements in con- nection with deformation for optimization, fabrication and inspiration. The purpose is to create a process from ideas on sketch to a realizable project through scripting, parametric design and algorithmic modelling. The motivation and inspiration for this project are the smooth shapes that come from bending and deforming simple elements. Furthermore, the fact that these shapes come from the very nature of minimizing internal potential energy, makes this approach very interesting in terms of both architecture and engineering. Scripting and parametric modelling allow for generation of complex geometry. In combination with engineering knowledge of geometry, material behaviour, constraints, external influences etc., parametric design is a great source of opportunities to fulfil creative ideas. Almost everything can be generated digitally and digital fabrication allows for production in most cases. However, sometimes these procedures become costly, material intensive and therefor often not sustainable. When an ad- vanced shape needs to be cut out of sheets or blocks, there will be material waste, some of which can be recycled, however, this also uses energy. By thinking and scripting, complex and optimised projects can be built simply and sustainably. This thesis aims to demonstrate how. page 2 Title sheet DTU - MSc. Architectural Engineering Master thesis - Autumn 2012 (E12) - 30 ECTS Points Subjects: Architectural Engineering Parametric design Optimization Supervisor: Henrik Almegaard - DTU - hal@byg.dtu.dk Business partner: Henning Larsen Architects Jakob Strømann Andersen - JSTR@henninglarsen.com Project period: The project work is carried out during the period from 03.09.12 - 25.02.13. This period includes 3 weeks of vacation. Hand-in: 25.02.13 All rights Rasmus Holst, Autumn 2012. Thesis done by: Date: Signature: Rasmus Holst, s061860 page 3 Preface This thesis is the conclusion of my Master program in Architectural Engineer- ing at the Technical University of Denmark (DTU) At the beginning of this thesis the direction was set out by the belief that a combination of curiosity, programming skill and craftsmen experience held the potential of interesting and optimised design. The amazing collective around the parametric forum of Grasshopper3d has been an amazing resource. Especially the likes of Daniel Piker (Kangaroo), the team behind Karamba3d and many others have been very helpful and inspi- rational. The collaboration with Henning Larsen Architects has proven very interest- ing and useful. Especially thanks to Jakob Strømann-Andersen who has been great at putting my solutions to the test in ongoing projects. Also thanks to some really nice colleagues and to the entire firm for setting me up with computers, software, modelling room, laser cutter, printers etc. Last but certainly not least, a big thanks to Henrik Almegaard for great guidance, advice and inspiration throughout this project and my entire study time at DTU. It has been very interesting doing this thesis and I hope that you will enjoy reading it as much as I have enjoyed working with it. Isabella Realce Isabella Realce page 4 Report layout This report is divided into 8 chapters. Firstly an introduction to the thesis problem statement, motivation and meth- od are given. To guide the reader through the process of this project, the report is set up in more chronological order than the actual iterative process. This way chapters 1-2 introduces the thesis and the principles of parametric design. Case[0] in chapter 2 exemplifies parametric design in action. Chapter 3 is an initial research into structural principles from simple ele- ments. This sets up an outline for overview and inspiration. One principle is chosen for further investigation in the following chapters. (think) Chapter 4-6 sets up the theory of physical modelling and investigates script- ing results. The method build in chapter 4 and 5, is tested on Case[1] in chapter 6. (script) Chapter 7 goes through the final case work, using the theory, methods and scripts build through the project in case[2]. The case is a pavilion design and focus is on fabrication and build ability. (build) Finally chapter 8 reflects upon obtained results and perspectives. When ever this logo is shown close to an illustration, a corresponding anima- tion can be found on www.vimeo.com/rasmusholst/albums. Click on the album “Think, Script, Build”. page 5 1 2 3 4 5 6 7 8 think Introduction Case [0] Initial research Modelling Investigation Case [1] Case [2] Reflection script build page 6 table of contents 1 Introduction page 16 1.1 Architectural engineering 16 1.2 Historical perspective 16 1.3 Parametric design 18 2 Case [0]: EPO page 26 2.1 European Patent Office - Introduction 26 2.2 Parametric facade design. 28 2.3 Optimization 30 2.4 Scripting 32 2.5 Parametric studies 34 2.6 Discussion 38 2.7 Perspective 40 2.8 Part conclusion 42 3 Initial Research page 46 3.1 Simple advanced structures 46 3.2 Gridshells 64 4 Modelling page 68 4.1 Paper play 68 4.2 Theory 70 4.3 Physical modelling 72 4.4 Definition breakdown [Spline] 76 4.5 Plate modelling. 78 4.6 Connection modelling 87 4.7 Definition breakdown [Mesh] 90 4.8 Part conclusion 92 page 7 5 Investigation page 96 5.1 Jukbuin pavilion 96 5.2 Jukbuin pavilion - Script 100 5.3 Jukbuin pavilion - Build 130 6 Case [1]: Nordea Bank page 134 6.1 Nordea bank ørestad - Introduction 134 6.2 Method 136 6.3 Form studio 138 6.4 Example 140 7 Case [2]: Pavillion page 166 7.1 Introduction 166 7.2 Concept 168 7.3 Form studio 170 7.4 Structure 172 7.5 Fabrication 174 7.6 Part conclusion 176 8 Reflection page 180 8.1 Discussion 180 8.2 Perspective 182 8.3 Conclusion 184 9 Bibliography page 186 9.1 Resources 187 page 8 Background Background The digital age has given access to tools for architects and engineers that allows for creation of complex geometry and advanced systems. At the same time there is a great demand for affordable solutions, sustainability and optimization. In the process of optimization one looks for the best solution of weighted parameters within a given space of solutions. When it comes to efficiency of buildings, there is a great geometrical challenge for the architect and the engineer in choosing the right solutions from the beginning. Parametric design In a design process, the solution space within the concept is often endlessly large. This gives thousands of possible combinations of angles, lengths, heights etc. The normal procedure is to boil this solution space down to a few proposals, chosen on the basis of intuition, aesthetics, analysis and/or experience. Scripting allows for designing parametrically, which enables the setting up of intelligent systems. These systems become intelligent by adding information to geometry, often points, nodes and lines. Through iteration processes, in which equilibrium of the stored information in the system is searched for, the system becomes self-emergent*. In some literature this is compared to ant hills, mouldfungi, bird flocks and schools of fish. Here each individual has a simple local knowledge about its needs and tasks. This is what makes the global system work and achieve its goal. This theory of self-emergence is a matter of big discussion, research and investigation. The basic insight in this phenomena, “wisdom of the crowds”, is in short that useful informations can be obtained via many shots in the dark. Scripting allows the designer to make the computer go through many solutions and output wanted results and consequences. * Emergent - Developing. Under development. Isabella Realce Isabella Realce Isabella Realce page 9 Mimicking nature As engineers we are used to analyse proposals for structures of different kinds. That being energy efficiency of facades, structural behaviour of build- ing elements etc. We have to predict the output of our project before it is build. For centuries theory has been built on this subject, and there is a lot of methods and software that help us predict consequences of more and more advanced systems. When it comes to structural performance we usually take our starting point in the un-deformed state of elements. One exception is the prestressed concrete beams and slabs. The prestressing has the advantage of creating opposite stresses to those coming from imposed loads. Therefor it increases the element performance, while it decreases the resource usage. Maybe the reason why engineers and designers do not utilize this behaviour more, is the complexity that lies behind the bending and twisting of elements. Mostly we strive towards linearity, planarity and thereby try to avoid bend- ing, all the while the design of architects tend to get more organic. At the same time it is known that simple non-rigid elements can gain stiffness from deformation into double curvature. By setting up an intelligent system, using scripting, it is possible to mimic the behaviour of these elements and to setup tools for form-finding, simulation and analysis. Form finding Form finding is the abstract modelling of material organisations as the active- ly negotiate internal and external influences. These can be laws of physics as well as architectural affect, spatial requirements and performance demands. The traditions has a long history that stems not only from the physics, but Fi g. 1 B eh av io ur in n at ur e Isabella Realce Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 10 also from the desires of designers and engineers to invent and innovate within the space of possibilities. Amongst others in this history is the in- vention of a description of the catenary curve and the reciprocal funicular curve by Antonio Gaudi, used for designing compression only structures. Frei Otto’s study and abstraction of tendencies and behaviours of minimal surface organisation found in soap film, led the way to novel knowledge of membrane structures. The expansive learnings of Frei Otto’s distillation and abstraction of materiality has also enhanced the knowledge and ability to design large span shell, lamella and lattice structures, even though they are constructed from seemingly contradictory materials. Algorithm Knowledge of a given material’s properties and/or molecular anatomy needs to be established as a computational description of the self-organisation. In Frei Otto’s soap film the setup can be understood as the process of one molecule acting upon another while negotiating influences. A contemporary method is the use of particle-spring systems that digitally simulates soap film structures. In terms of architectural geometry, such as surfaces, volumes etc., it is represented as a network of particles hitched to one another by springs. Equilibrium is found via numerical iterations. Two common strategies are dynamic relaxation or the force density method. Both uses the mathematics of Hooke’s laws of elasticity. The algorithm allows for implementing architectural schema also. Such as to define for example the front door. This becomes another layer of influences or motivations that is to be negotiated within the system. Digital form finding is not to replicate the work that has preceded it, but rather to seek out new territories. Wood These methods can be used to describe many different materials and be- haviours. The focus of wood in this thesis is purely a case of interest and admiration of the sustainable, flexible and aesthetic nature of the material. Fig. 2 Gaudi chain model Fig. 3 Frei Otto - Optimized path experiments Fig. 4 Wood materiality Isabella Realce Isabella Realce page 11 Problem statement How can parametric design be implemented in an architectural design process and become added value in terms of modelling speed, time, analysis, optimiza- tion and development. From this perspective, the intention of this project is to discover if and how we can use simple, regular building elements in the construction of the in- creasing numbers of complex shaped architecture projects. The solution to this problem is interesting to all parties in a building pro- ject; designers, engineers, investors, entrepreneurs and so on, in terms of economy, optimization, sustainability and build-ability. The title of this report - think, script, build - is the short description of the approach that will be taken in discovering the above problem: How can script- ing be used to simulate the deformation of simple elements and networks and thereby become a tool for form-finding, analysis and building descriptions of complex geometries. The interdisciplinary method of architectural engineering will be used in com- bination with parametric modelling of digital systems, that become intelligent by scripted information, for architectural projects. Isabella Realce page 12 process | disposition Method At the beginning of the research, this project looks at interesting structures and principles of more or less simple and regular elements. An outline of this initial research is set up for inspiration and overview. One of these principles are chosen for more thorough explorations within the think, script, build ap- proach. To begin with, an introduction to parametric design and scripting is given by brief explanation and exemplification through case studies together with Hen- ning Larsen Architects. By doing so, common ground for further collaborative investigations are established. Then the script for parametric design of the chosen structure principle is build in an iterative process consisting of theory, exploration/experimentation and casework. The idea behind think, script, build is to set up an effective and interactive workflow between the three parts. This means working in and out of the computer, sketching and creating ideas, scripting and building digital paramet- ric models. The building of the parametric model strives towards real time user control, simulation and analysis. To be able to analyse the model real time and find responses to any changes made, the model is linked with internal and external calculation engines. The chosen main software is Rhinoceros3D, from Robert McNeel & Associ- ates, a 3d modelling software with many plugin and extension possibilities. Grasshopper3d is a visual programming language plugin for Rhinoceros3D, developed by David Rutten. Grasshopper3d also implements more common scripting languages, such as Python, VB, C# etc, as well as many application plugins for different use. Isabella Realce page 13 Summation of method: - Introduction to parametric design. - Gathering of construction principles - Wood structures. - Aggregate/module structures - Newer installation structures. - Buildingof script(s). - Theory: Materials, properties, physical model. - Experimentation and comparison - Connections - Intelligent system. - Linkup with other analysis software - Implementation. - In collaboration with Henning Larsen Architects method and principles are tested on case studies of competetion projects. - Model/pavilion - Building of 1:1 scale model. The described method is not chronological, but should be seen as an itera- tive process. This process is illustrated as the time line on Fig. 5 setup at beginning of this thesis. study theory test/explore case01 case02 case03 writing conclusion theory test/explore model paper september october november december january february 1:1 part model report Preliminary time schedule - proces 2013 AAG12 Conference and Solar decathlon: 25.09.12 - 08.10.12 Fig. 5 Preliminary timeline page 14 [INTRODUCTION] page 15 [Architectural engineering] + [Parametric design] Rhino Grasshopper page 16 1 | Introduction 1.1 Architectural engineering 1.2 Historical perspective Architectural engineering is intended to bridge the gap between architects and engineers. Meaning that the architectural engineer is involved in the project from the early design stages, working closely with the architect to evaluate and contribute in choosing the best solution of a given design. “The role of architectural engineers can overlap with that of the archi- tect and other engineers. Like architects, architectural engineers seek to achieve optimal designs within the overall constraints, but mainly use engineering tools to attain their goal.” (DTU MSc. Architectural Engineering 2012) Using the technical knowledge in a creative way is meant to lift the archi- tectural visions in a way that optimise and implements the ideas of the ar- chitect. In doing this, one strives towards creating a fusion between art and science. Early considerations of structural behaviour, energy consumption, material etc. helps in optimising the design. Small changes to the geometry or materiality, can have a big impact on the structure, amount of daylight, heat transfer, build-ability etc. There are many parameters to adjust and therefor an almost endless amount of solutions. Parametric design allows changing parameters of the project and quickly review the consequences without having to redo everything. This becomes the ultimate tool for architectural engineering, combining aesthetics, sci- ence, math and analysis in the same model. Every change made to the design has an impact on the performance and can easily be reviewed real-time. A significant inspiration for this mentioning of architectural engineering are the likes of important people, amongst others Antonio Gaudi, Mies van der Rohe, Buckminster Fuller, Pier Luigi Nervi and Frei Otto. Each of them combin- ing arts and sience using different approaches. Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 17 Fig. 4 Frei Otto 1.2.1 Mies van der Rohe and Bauhaus. Ludwig Mies van der Rohe was one of the three architect directors at Bau- haus. The German school combined crafts and the fine arts and became one of the most influential currents in modernist architecture. One of the main objectives of this school was to unify art, craft and technology. 1.2.2 Buckminster Fuller and the Dymaxion World. Richard Buckminster Fuller spent his life working across multiple fields, such as architecture, design, geometry, engineering, science and education. He described himself as “a comprehensive anticipatory design scientist”*. The concept of Dymaxion - DY-namic, MAX-imum, tens-ION is the idea of the most efficient overall performance per unit of input. 1.2.3 Pier Luigi Nervi Italian architect and engineer who did great innovative research in applica- tions of reinforced concrete structures, especially working with thin shell structures. He stressed that intuition should be used as much as mathematics in design. Like Heinz Isler, Felix Candela and Eduardo Torroja, Nervi looked towards Gaudi’s funicular models. 1.2.4 Frei Otto Frei Otto is the leading authority on lightweight tensile and membrane struc- tures and has pioneered the advances in structural mathematics and civil en- gineering. His work on optimization of structures and formfinding by looking at nature, is still a great inspirational source in the parametric environment. ** Common to them all is that they are working with the beauty within knowledge of science. This enables them to work and design across multiple fields and thereby create interesting and optimised structures. However, they did not have the same access to digital tools and emerging technologies as we have today, therefor it is interesting to look at future developments of their ideas and knowledge. * http://bfi.org/about-bucky ** Finding From - Frei Otto (1996) Fig. 1 MIes van der Rohe Fig. 2 Buckminster Fuller Fig. 3 Pier Luigi Nervi Isabella Realce 30 0 BC 50 0 B C 1947 1963 1977 1978 1982 2008 page 18 1.3 Parametric design Fig. 5 space ruler.png 1.3.1 What is parametric design? When googling the word “parametric design”, it is one of the few searches where the first hit is not a wikipedia explanation. This is probably because their is no precise definition, rather there is a lot of related terms; genera- tive design, algorithmic design, node-based design, logical modelling, program- matic modelling etc. But these notions are not very good and a bit latent - basically it is a far more sophisticated way of modelling digitallly. Many times when modelling a concept, often certain operations are monotone and repetitive, operations that can be considered as algorithms. A good exam- ple of such is the “array” tool in most CAD software* - a way to repeatedly move and copy elements. The physical aid of “array” would be the Linex line spacer (Fig. 5). Instead of doing it manually and use time on drawing, erasing and redoing, we can use the abilities of computers to work with algorithms. Imagine that you are drawing the facade of a skyscraper. Each floor has 8 windows, divided evenly along the length of the facade. It is simple, but after drawing it in the morning, you find out that you need bigger windows, then you find out that you need more windows, then the facade size is decreased, then it is rotated, then skewed - with maybe a thousand windows, you are going to use a lot of time. Algorithms will make the computer do your calculations and draw your geometry. Making the computers do your calculations and run algorithms has been around for a long time. Describing rules for geometry started with Euclid approximately 300bc. Far back the first calculator, the abacus, is believed to have been used. The age of computation started when William Shockley invents the transistor in 1947. This leads the way to circuit boards, electronic calculators and computers. * CAD - Computer aided design. introduction Isabella Realce Isabella Realce 30 0 BC 50 0 B C 1947 1963 1977 1978 1982 2008 page 19 300 BC: Euclid - Elements. 500 BC: Ancient greek Abacus. 1947: William Shockley invents the Transistor. 1963: Ivan Sutherland writes SketchPad. Graphics. 1977: Dassault wirtes Catia. 3D drawing 1978: Hewlett Packard - First PC’s. 1982: Autocad first release. 2008: David Rutten invents Grasshopper3d. page 20 The concepts of the abacus and the knowledge of Euclid was combined by Ivan Sutherland in 1963, when he wrote the first CAD-application SketchPad, where the designer interacted with the computer graphically by using a light pen to draw on the monitor. SketchPad evenincluded a solver that allowed assigning constraints, such as lines being individually perpendicular**. Ivan Sutherland described himself as being a visual thinker, therefore he had his interest in computer graphics, saying: “...if I can picture possible solu- tions, I have a much better change of finding the right one.”*** In the late 1970s simpler operating systems and the release of desktop com- puters encouraged engineers to experiment with programming and became the start of workstation computing. The development in CAD grew fast during the 1980s, during which the software Pro/Engineer (1987) by PTC and more famously - AutoCAD (1982) by Autodesk was released. In 1992 the McNeel group integrated their NURBs geometry library in AutoCAD and in 1994 McNeel released the first beta version of Rhinoceros3D (Rhino). Pro/Engineer (1987) was the first software to fully implement the concepts of SketchPad (1963), where constraints and solvers created the basis for parametric design. FInally in 2008 David Rutten invents Grasshopper for Rhino Programming and finite element analysis has been used for a while by engi- neers, but the visual programming interface of the plugin Grasshopper for Rhino has taken programming to a familiar place and this has created a com- mon playground for architects and engineers. In the following, the use of Grasshopper will be explained. ** SketchPad on youtube: http://www.youtube.com/watch?v=mOZqRJzE8xg *** Ivan Sutherland. http://history-computer.com/ModernComputer/Software/Sketchpad.html Fig. 6 SketchPad Demo (1963) introduction Isabella Realce Isabella Realce page 21 “Hello John. We are going to show you a man actually talking to his computer.” - Prof. Steven Coons, MIT (TV Show 1963). “..if I can picture possible solutions, I have a much better change of finding the right one.” - Ivan SUtherland Fig. 7 Youtube - Skethcpad demo Fig. 8 Ivan Sutherland page 22 1.3.2 Rhino + Grasshopper Grasshopper was written by David Rutten in 2008 for McNeel. David studied architecture at TUDelft, where he got tired of the lack of scientific approach in design. All designs where based on emotional or philosophical considera- tions. He wanted to see numbers and proof that some solutions where better than others. Similarly to the likes of Frei Otto and Nervi, he implements tech- nical knowledge as well as emotions, philosophy in the evaluation of design using Grasshopper. There are many different descriptions of Grasshopper; a visual algorithmic interface, visual programming, Visual Basics without the Basics and many more. Briefly how it works : There are two basic elements - data and actions. Every step of connecting components is like lines in a source code, except there is no code. All boxes can be considered to represent small pieces of code. As with cod- ing, all commands take inputs and creates output through the requested action. These Grasshopper scripts will be referred to as definitions throughout this report. This method is very handy in speeding up the drawing process and having ultimate precision, but it is the access to all data, that makes it really inter- esting. Especially for engineers, treating the data mathematically has a great potential. Similarly to the visual approach of Ivan Sutherlands (cf. p. 20), Grasshopper enables real-time visualization of solutions and consequences and it thereby becomes a great media within a competition team. 1.3.3 Parametric design in action. So apart from drawing spheres on a line, how is parametric design an added value to an architectural company like Henning Larsen Architects? The thesis statement is that parametric design will speed up the modelling processes. It might take longer to set up a good script, than doing the first drawing. From Fig. 9 Points + line comp. DATA ACTION Fig. 10 Step 1. Pts + line Fig. 11 Grasshopper Infacade. Rhino Viewport Isabella Realce Isabella Realce Isabella Realce page 23 DATA ACTION DATA ACTION Fig. 12 Step 2. Divide line Fig. 13 Step 3. Draw spheres here on however, the script will create changes within seconds. On top of this, the open platform, that Rhino3d and Grasshopper is build upon, enables linking the model with analysis tools for optimization of e.g energy use and structural efficiency. 1.3.4 Software confusion Because this thesis is based on a modelling software, Rhino, the Grasshop- per plugin and plugins and extensions for Grasshopper, it is very easy to be confused as a reader. Therefor explanation icons will be presented at the introduction of each chapter. The plugins for Grasshopper are really impor- tant as they add different extended abilities of the scripting interface. All extensions will be explained when used, but here in bulletform: [DIVA] [Karamba3d] Rhinoceros: 3D modelling software. Basis for modelling. The builder. Grasshopper3D (GH): Visual scripting interface plugin. Tells the Rhino what to do. Python: Scripting language plugin for GH. Intelligent helper for the Grasshopper. (Mentioned Python scripts are coded by the author) Kangaroo: Physics engine plugin for GH. Simulates physical behaviour for the Grasshopper. Galapagos: Evolutionary solver plugin for GH. Goes through solutions for the Grasshopper. DIVA: Daylighting and energy modeling plug-in. The Grasshopper’s energy advisor Karamba3D: Finite Element program fully embedded in GH. The Grasshopper’s structural advisor. In the following chapter the principles of parametric design will be tried out and explained by implementing these methods on an, at the time being, ongoing competition project together with Henning Larsen Architects. The case is meant to shed light on the possibilities of interactive analysis and optimization of a facade, using parametric design. page 24 CASE [0] page 25 [European Patent Office - New main office] [Hague] Rhino Grasshopper Python Galapagos DIVA page 26 2 | Case [0]: EPO 2.1 European Patent Office - Introduction 2.1.1 About the case The European patent office in Rijswijk - the Hague, is building a new main of- fice. The competition team is Henning Larsen Architects and Arup. At the time of the work carried on this case, the project is in its 2. phase and a new and more innovative approach is asked for. The European patent office stands for innovation and new inventions as well as looking backwards in history. Therefore they want this to be noticeable in their new main office. The people working at the European patent office are working very individu- ally and needs to be very focused on their assignments, as well as doing very thorough research. Therefore a proposal of individual cell offices is chosen. These offices are where the employees can focus in quiet. Then they can meet up with their colleagues in open interactive common spaces. As these cells take up the majority of the collected office area and of the facade, these are of main interest in the energy optimization. Some of the important keynotes for the project are: - Maximum individual user comfort. High individual control of comfort. High degree of concentrated work with great views. - Optimal functionality. Flexibility in the use of spaces. Quiet work-space vs. interactive areas. Strong central interactive connection areas between departments. - Optimal design development and implementation. Future proof design solutions. page 27 THE VERTICAL HINGE VI EW TO TH E HI GH W AY VI EW TO TH E HA GU E EP O I (S HE LL) THE HINGEPIVOT FOR VIEW INTEGRATE INTO SITEENTRANCEEPO PLAZA ONE FLOOR = TWO SPATIAL MODULES SP AT IA L M OD UL E SP AT IA L M OD UL E Fig. 2 Main concept. Henning Larsen Architects © Fig. 1 New main office - Birdview. Henning Larsen Architects © page 28 2.2 Parametric facade design. 2.2.1 Math surface An idea of individual working cells within a bigger organism was the driving force for the proposals. The important aspects of the facade is to be energy efficient in terms of solar shading, natural daylight, glare, air quality, heating and cooling for the individual cell workspaces. To introduce the method of parametric design, the following example uses an algebraic surface as an attractor for the solar shading. In this case the idea was that the variation of the surface could enable self-shading and an interesting expression. Here the algebraic surface called a “monkey-saddle- surface” is chosen. This has the algebraic equation: To create shading, relating to the saddle surface, a point-grid is set up on the surface for each cell office. The x- and y-values of each point in the planar grid is extracted. From these the corresponding z-value is calculated. In this case the operation is done in the xz-plane, meaning it is the y-value that is calculated. The rectangular edge of each cell on the planar surface is then extruded towards the algebraic surface. 2.2.2 Variations Parameters in this script are variables multiplied with the x- and z-values, the interval of the representation of the surface and a damping coefficient. The sliders in the script represents these variations and every change can be seen in the Rhino viewport - see Fig. 3. For each solution an evaluation can be carried out. To make an example, here the material usage is extracted. In an Excel spreadsheet, a specific solution to an equation can be found by use of the goal seek utility. A similar tool is the extension Galapagos Evolutionary Solver for Grasshopper. x(u,v) = u y(u,v) = v z(u,v) = u3-3*u*v2 z=x(x2-3y2) Fig. 3 Rhino Viewport Fig. 4 Sketches Isabella Realce page 29 Fig. 6 Render Fig. 5 Grasshopper definition. The script is set up to input the variables of the surface as input to the solver . These inputs are called genomes. Then a “good enough” value or fitness-value is defined in order for the solver to be able to find a solution. The solver basically choses a combination of genomes within a certain range and determines if this combination is good or bad. There is a lot of theory behind the evolutionary problem solving and a lot more to explain about Galapagos, but it will not be explained in detail here. For more info see: http://www.grasshopper3d.com/group/galapagos The important thing to know, is that Galapagos enables automation of the evaluation and optimization process. In this example the surface variables are the genomes, and the goal is to fulfil the fitness function best possibly, within a chosen interval of the variables. Next step is to define a good fitness value defining the actual goal. In this case the goal is the minimum amount of material and the minimum of solar gain. A numerical value of minimum solar gain is simplified to being the minimum area of solar radiation for optimization. Using this method on the design chosen by the architects, is shown in the following. Isabella Realce page 30 2.3 Optimization 2.3.1 What is optimization? Optimization is the selection of the best solution. Selection with regard to some criteria from some set of available alternatives. In the case of para- metric design it is all about setting up the script so that it matches the idea and allows for the necessary variations. Especially for geometry, this means setting up a logic for interaction and interconnection of points, lines and surfaces. The chosen design for the shading is a irregular cassette (Fig. 8). So here the exercise is to look at best variations of the corners in terms of maximum shading and material consumption. It is clear that the best solution for minimum material usage is the smallest cassette possible. At the same time one of the most efficient solutions to minimum solar gain is obtained by a maximum amount of shading or cassette size. The graph below shows the obvious - as the size of the casette in- creases, material usage increase and solar gain decrease. However there are solutions with different amounts materials, that gives a similar result in solar gain. So a defined fitness value is needed to use the Galapagos solver and this is possibly the most important part of using an evolutionary solver. Fig. 7 Materials / solargain relationship Case [0]: EPO Isabella Realce page 31 2.3.2 Fitness functions Darwin’s Theory of Evolution states survival of the fittest. But it can be very difficult to say what it means to be fit. In evolutionary computation, however, fitness is a much easier concept. It can be what ever it is wanted to be, because we are trying to solve a specific problem. Therefor we know what it means to be fit. The designer needs to figure out which parameters and goals are the most important ones. Lets try and set up the fitness function in this case. The material consumption is named A and the solar radiation B. The distance from the outer corners to the corresponding inner points is set to an interval of {1 -> 1000}mm. The interval starts at 1 for computational reasons. Firstly the best and worst possible fitness values for A and B is set up. This is calculated by using the script and gives: In table form: The fitness function: for minimizing both parameters is: The above function just states that we want to minimize A and B. Now it needs to be normalized, meaning only having values from 0 to 1, and to be- weighted considering the range.* Then this gives: The value of this fitness function is for an extended version of the cassette shown here (see Fig. 10 on page 33), by adding an extra variable point in the centre. * http://www.grasshopper3d.com/forum/topics/galapagos-multiple-fitness Fig. 8 Cassette principle A= matCons. B= radArea Best fitness: {A=4, B=86} Worst fitness: {A=4202, B=4667} A {min=4; max=4202; range=4198; target=4} B {min=86; max=4667; range=4581; target=86} f=-A -B f=-((A-4) / 4198) - ((B-86) / 4581) A= matCons. B= radArea Best fitness: {A=4, B=86} Worst fitness: {A=4202, B=4667} A {min=4; max=4202; range=4198; target=4} B {min=86; max=4667; range=4581; target=86} f=-A -B f=-((A-4) / 4198) - ((B-86) / 4581) A= matCons. B= radArea Best fitness: {A=4, B=86} Worst fitness: {A=4202, B=4667} A {min=4; max=4202; range=4198; target=4} B {min=86; max=4667; range=4581; target=86} f=-A -B f=-((A-4) / 4198) - ((B-86) / 4581) A= matCons. B= radArea Best fitness: {A=4, B=86} Worst fitness: {A=4202, B=4667} A {min=4; max=4202; range=4198; target=4} B {min=86; max=4667; range=4581; target=86} f=-A -B f=-((A-4) / 4198) - ((B-86) / 4581) Isabella Realce page 32 The definition is build up in two parts. The calculation of the sun position (cyan) and the generation of geometry (magenta). The sun calculation part, calculates the sun position at a specific time at a specific location and is based on a slightly refined version of a definition by Ted Ngai Jan and his visual basic script (VB). This script is build upon the solar position algorithm by NOAA*. The second part is where the shading geometry is created and the radiated area is calculated. The engine of this part is the Python script** which turns the facade in to an intelligent system. In this system each cell knows about its facade mesh, normal vector, inner and outervertices, geometry of the fins and it runs the radiation calculation internally. The output of this script is the fin geometry and the radiated area as line geometry, for faster computation speed. This can then be visualized as solid geometry and the area data is used for optimization using the fitness func- tion mentioned in 2.3.2. The variable distances (grey) for the outer vertices become the genomes for the Galapagos Solver and the fitness function is used for the to look for the best combination. The definition can of course be used without Galapagos. Instead of letting the solver go through all combinations, one can set up different extremes and in between values. These can be evaluated in terms of aesthetics and per- formance to give an impression of the direction to take. This more “manual” evaluation has the advantage of control and speed, but one might very easily miss the most optimal combinations. * National Oceanic and Atmospheric Administration - U.S. Government ** See appendix A 2.4 Scripting 2.4.1 Grasshopper definition Case [0]: EPO page 33 north 12:00 sunrise sunset Fig. 9 Grasshopper definition. Fig. 10 Rhino viewport. page 34 2.5 Parametric studies 2.5.1 Script calculation - example This way of systematic modelling with an intelligent system behind, allows the designer to evaluate aesthetics and performance at the same time and get an idea of in which direction to move forwards. In this case the performance output is material consumption, radiated area and the relation between the two. Studies like these are a good way of gaining common ground for collaboration between architects, engineers and other consultants. One the right hand side is an example of an evaluation schedule for discussion. Having numbers on the performance, while studying design solutions, enables designers and engineers to decide whether something is better than something else - both in terms of aesthetics and performance. From here they can move on together. A similar manual method is common practice at Henning Larsen Architects. In such a practice, a model is normally build in a modelling program to visualize and it is then transferred or rebuild in an analysis program. The difference is the speed and precision that comes with the parametric modelling. The fol- lowing will show how linking software enhances this procedure. sun 5 ,63 m2 mater ia l 3141 m2 rel . 0 ,98 Fig. 11 Evaluation step - example. Case [0]: EPO Isabella Realce Isabella Realce page 35 Summer solstice, 21st June 10 AM 12 AM 14 AM 10 AM 12 AM 14 AM Equinox, 31st March EUROPEAN PATENT OFFICE Parametric optimization of facade structure sun 5 ,57 m2 mater ia l 3070 m2 sun 5 ,29 m2 mater ia l 2800 m2 rel . 1 ,041 rel . 1 ,025 sun 5 ,63 m2 mater ia l 3141 m2 rel . 0 ,98 sun 10 m2 sun 0 .66 m2 sun 5 m2 mater ia l 1 ,2 m2 mater ia l 16 ,6 m2 mater ia l 10 m2 rel . 0 ,06 rel . 13 , 1 rel . 1 Fig. 12 Example of schedule page 36 2.5.2 DIVA Analysis As mentioned in part 1.3.3, the open platform of Rhino3d and Grasshopper, as well as the increasing interest in the software, seems to make it an interest- ing place for software developers. There is many different kinds of plugins that will extend the abilities of Grasshopper. Some plugins work with an in- ternal calculation engine, meaning that everything is done within Grasshopper and Rhino. Other plugins acts as a translator between external software. These plugins work like adding specialist tools to the toolbox. DIVA-for-Rhino is a daylightning and energy modelling plug-in, initially for Rhino. DIVA-for-Grasshopper plugin extends these tools to Grasshopper. In- stead of having the script doing simple geometric calculations of the radiation area, this software extension allows for much more advanced analysis. DIVA links validated simulation engines like Radiance, Daysim and Energy+.* In this case it was important to find a shading configuration that allowed enough natural daylight into the room, while minimizing the solar radiation on the glass, in order to minimize overheating. That means that an algorithm that optimise the geometry, in relation to both the daylight factor and the solar radiation, is needed. To do this a single cell office is modelled in Rhino and the parametric shading is created in Grasshop- per through the same custom Python script as before. This time the calcula- tion code is taken out of the script, so that it only creates the geometry. The dynamic shading geometry is then analysed in e.g. Radiance, through DIVA. DIVA uses the analysis engine of, but does not open, these programs and gives fast feedback. Depending on the numerical goal, the fitness function is defined and using the Galapagos solver, the best solutions can be found. * See www.diva4rhino.com for documentation Case [0]: EPO Fig. 13 DIVA data output. Isabella Realce page 37 Fig. 14 GH Def. DIVA + Geometry script Fig. 15 VIsual representation of daylight factor and radiation on window. See animation on www.vimeo.com/rasmusholst page 38 Case [0]: EPO 2.6 Discussion As a part of the research area of this thesis, a discussion of how far to take the written code is interesting. Here the Python script for the geometry was setup in collaboration with the competition architects. This script divides the facade into the individual cell offices and creates a parametric geometry of the solar shading as explained previously. Then two different approaches was used: (1) Calculation of radiated area and material usage inside the script (2) Link to external analysis software through DIVA The first approach (1) has the advantages of simplicity and interaction speed. This means that each iteration is executed fast and therefor can be executed in higher numbers - e.g. on the whole facade at once. This can be an advan- tage as the aesthetics of the facade can be evaluated while going through the optimization. But at the other hand this simplicity means that only the direct sun on the facade is taken into account. The link with external software (Radicance, Energy+ etc.) makes it possible to see all the effects of each iteration step - this being solar irradiation, illuminance, daylight factor, thermal performance etc., but these more detailed processes takes longer to simulate. Here ap- proximate 10 seconds pr. change It is clear that in order to be able have full control in approach (2), the de- signer needs to know about the software that DIVA links to. It is necessary to know the setup of the models in order to understand the output that comes back into Grasshopper. page 39 Fig. 16 Scripting only. Rhino + Grasshopper screenshot Fig. 17 Script linked with DIVA engine. Rhino + Grasshopper screenshot EPO | SCRIPTING EPO | SCRIPTING + DIVA page 40 The geometry here was relatively simple and the focus was on energy con- cerns. It is not hard to imagine doing the modelling and the analysis manually. In cases of more complex geometry, the strength of intelligent systems and parametric design would come to show. The idea of individual cells within a working organism was the driving force for these other proposals: 2.6.1 Origami cell Origami is folding of a single element into smaller individual compartments. This principle has the properties of using planar and relatively simple ele- ments as well as having an interesting spatial expression. The idea is to somehow figure out and list the building DNA and map the needs of each part by the folding origami structure. Meaning that needs for solitary confinement, shading, views, acoustics and so on are accounted for by the size,direction, angles etc. in each origami compartment. (Fig. 18) 2.6.2 Voronoi cell When thinking about cells from a mathematical point of view, the Voronoi diagram is the first thing that comes to mind. The Voronoi principle can be used in two or three dimensions, and can be applied in one or more layers. As for the origami principle, the distribution of Voronoi cells accommodate for the needs of each individual office. Some cells might spread across of- fices because of similar needs or external impacts. Especially when adding a third dimension and thereby different angles out of the plane of the facades, this principle becomes really interesting in terms of structural and shading optimization. (Fig. 19) 2.6.3 Karamba3d - Finite Element Analysis. As the geometry becomes more complex, alternative analysis tools are nec- essary. DIVA proved handy for energy analysis. When it comes to structural analysis, plugin Karamba3d, provides the same kind of flow as DIVA. Here tested on a parametric freeform truss. (Fig. 20) Case [0]: EPO 2.7 Perspective Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 41 CELL | ORIGAMI FOLDING CELL | VORONOI_math FREEFORM | TRUSS_analysis Fig. 18 Initial sketches and references. Fig. 19 Initial sketches and references. Fig. 20 GH definition + Karamba. Freefom truss example (RH). page 42 Using the parametric model and analysis tools, enables teams to optimise the shading design dynamically. Together with the Galapagos solver the process can be automated. This means that the designer or engineer can work on other things, while the computer solves the algorithms set up. So on top of saving a lot of time on drawing, redrawing, evaluating and starting over, it can be done automatically and perfectly precise. This immense increase in speed allows going through large number of itera- tions - which is the strength of the computer - and see some results that might else have been missed. Case [0] serves as an introduction and an example of parametric design in architecture projects. Case [0]: EPO 2.8 Part conclusion Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 43 Fig. 21 New main office - Collaborative zone. Henning Larsen Architects © Isabella Realce page 44 INITIAL RESEARCH page 45 [Construction principles] + [Overview] + [Inspiration] page 46 3 | Initial Research 3.1 Simple advanced structures 3.1.1 Introduction The strength of parametric modelling and scripting is the complete control over all aspects in the modelling. All inputs, outputs and constraints are ac- cessible. This control can be used to create complex systems, where constraints might be size of elements, connections, material strengths and so on. These are very rational things. Things that are meant to bridge the gap between draw- ing and building. In the book “Translations from Drawing to Building”* - Robin Evans talks about great inventions happening in this very gap. When a simple logic is combined with other simple logics, is twisted slightly or something similar, unexpected consequences might arise. This makes it pos- sible to narrow and explore the cap, at the same time. Instead of defining a method to execute a project, the method ends up defining the project. This is a way of manipulating the tectonic method to define the design. Set up correctly, construction information can be generated directly from the design information. Rather than having to figure out how to manufacture some complex shapes, it is already held within the design. Seemingly chaos can be nothing more than simple logics put into system. It is structures like these that will be explored in this chapter. It has been tried to define categories and to explain these in short, even though some principles will consist of overlapping tectonics, such that they might be put into more than one category. At the end of this chapter, one of these principles will be chosen for further investigation and exploration. * Translations from Drawing to Building and Other Essays - Robin Evans. (1997) Isabella Realce Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 47 page 48 system logic connection examples Se ct io ni ng Any 3D geometry can be constructed from planar elements by slicing through the geometry in two or more directions. Normally the geometry is sliced in two orthogonal directions and a grillage structure is created. This means that the ele- ments edges will have to be cut along the curvature of the geometry. A series of profiles are intersected and connected. This prin- ciple is known from air plane building and shipbuilding. The profiles acts as the structural ribs and can be clad after as- sembly. model Sectioning Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 49 references 4 2 3 1 1 2 3 4 Fig. 1 Indigo Deli. Sameep Padora & associates. Fig. 2 Serpentine Pavilion 2005. Siza, Moura & Balmond. Fig. 3 Metropol Parasol, Sevilla. Jürgen Mayer-Hermann. Fig. 4 Olympic stadion Beijing. Herzog & de Meuron. page 50 Folding turns a flat surface into a 3-dimensional structure. When folds are introduced into otherwise planar elements, those elements gain stiffness and rigidity. They increase their span distance and can often be self-supporting. The logic is that by introducing curves or lines on one or more planar sheets of material and rotating around these curves, a new 3-dimensional structure and thereby new spaces are generated. Folding is the further consequence of bending. In materi- als that allow plastic behaviour, the folding can plastic deformation of the material. Folding concepts can be used together with those of tessellation. Meaning that the folds are rather cuts and connections, in materials too brittle, for complete folding. Gregory Epps and ROBOFOLD uses Grasshopper + plugins to generate and simulate curved folding behaviour. While non- curved folding is much simpler to simulate. system logic connection model Fo ld in g Folding examples Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 51 Fig. 5 Richard Sweeney - Paper sculpture Fig. 6 Andrea Russo - Origami tessellation Fig. 7 Juergen Weiss - Barcelona Block Fig. 8 rvtr - Resonant chamber. Fig. 9 Ryuichi Ashizawa Architects - Folded Plate Hut 1 3 4 5 references 1 2 3 4 5 2 page 52 system logic connection model Shells Sh el ls A shell structure is a spatial structure that is economical in terms of materials if designed correctly. The curved shell surface geometry can be made out of one or more curved elements, in concrete for example, like the structures of Heinz Izler and Felix Candela. However the production of such elements are expensive and time consuming. The shell can also be divided into facets of planar elements. These facets can be modified to create certain properties in terms of light, structure, aesthetics etc. This division of the shell into planar elements without cap or overlap is also called tesselation. This tesselation can be divided into layers. Meaning that each division can be futher divisioned and modified in or out the original division plane. examples Isabella Realce Isabella Realce Isabella Realce page 53 references Fig. 10 Roskilde dome - Tejlgaard + Almegaard Fig. 11 Roskilde dome - Tejlgaard + Almegaard Fig. 12 BOWOSS Bionic Pavilion - Saarland University Fig. 13 ICD/ITKE Research Pavilion 2011 1 2 3 4 1 2 3 4 page 54 Bending or flexure ismovement out of one or more planes of a planar element. Bending occurs when applying external loads perpendicular to an element or in the longitudinal di- rection of the element. It also occurs from temperature and humidity differences. In engineering bending is referred to in 3 axis - bending of rods is 1-axis, for beams it is 2-axis and plates and shells it is 3-axis. If in beams we have “bending” around the longitudinal axis, we refer to this as torsion or twisting. To utilize bending of slender elements, an external load is applied and the elements are held in the deformed state by fixation. Elements can either be fixed to a predefined form work or in systems where internal relations create the bending. Otherwise non-rigid elements gain stiffness and structural stability by this deformation through bending - similarly to the description from folding. This can occur in the element locally and therefor it become even more significant in net- works. Gridshells are probably the most known structure where bending is utilized for an optimised structure. system logic connection model Be nd in g Bending Twisting examples Isabella Realce Isabella Realce Isabella Realce page 55 1 2 3 references 5 4 Fig. 14 Hermes Boutique - RDAI Fig. 15 Digital Weave - IwamotoScoot Fig. 19 Timber Fabric - IBOIS Fig. 16 Stripmodel test Fig. 17 Eclaireur Paris - Arne Quinze Fig. 18 ICD/ITKE research pavilion 2010 1 2 3 4 5 6 page 56 system logic connection model Network All structures work in some kind of network. Most of them are in practical systemized order. This order is of course to ease the drawing and building process. Such systems or networks are often orthogonal linear systems, as grids for example. The simplicity of these linear systems can be very at- tractive aesthetically. Nonetheless, chaotic and seemingly random structures has an intriguing appearance. Examples of such structures in nature are nests and beaver dams. The structural stability is created by interlocking of the elements. In architecture the interlocking is not restricted to the elements themselves, as the systems can be modelled with mechanical connections where ever. There are two main approaches: 1 - Elements, connections, logics etc. define the shape more or less randomly. 2 - Attraction of an element network towards a predefined surface defines the shape. Logic and algorithm needs to ensure structural stability. Rules might be: Each element needs to connect to at least two other elements, but not more than four. At least two of each connecting elements need to connect in a way that ensures triangles. All connecting elements need to be touch- ing in the same plane, but not intersecting. Many more and other rules might be necessary. Here an iterative process using Galapagos might be useful. Ne tw or k examples Isabella Realce Isabella Realce page 57 “There Is No Chaos Only Structure” - Arne Quinze (2011). references 1 2 3 4 Fig. 20 Uchronia - Arne Quinze Fig. 21 Roof installation - Arne Quinze Fig. 22 CityScape - Arne Quinze Fig. 23 Aggreation Anenom - Dave Vu and David Pigram 1 2 3 4 page 58 system logic model Modules Aggregates An aggregate is a collection of items that are gathered to form a total quantity. Most structures are made of a num- ber of elements. In most planar steel structures, beam and column elements are used to create a skeleton. In concrete structures, often precast modules in practical size are used. Somewhat related to the network system, it is important that the internal relations between adjacent modules. These need to have a common side, edge or some something else to connect them. It is this relation, the shape of each aggregate and poten- tially the transformation of these, that creates the overall shape and properties of the structure. This is what we now from many structures in nature - the backbone for instance. Each aggregate can be a module with individual properties, other than the structural. This might be light and thermal properties. Similarly to a window in a facade, each aggre- gate can be more less dynamic and respond to surrounding impacts. Fractals are a similar phenomenon, known from both nature and maths. Like aggregate structures, fractals show a re- peating, self-similar structure. Mo du le s Isabella Realce Isabella Realce Isabella Realce page 59 references Fig. 24 In-Out Curtain - IvamotoScott Fig. 25 Paper Art - Richard Sweeney Fig. 26 Voussoir Cloud - IvamotoScott Fig. 27 Harpa Concert Hall - Henning Larsen Architects 1 2 3 4 5 6 1 6 3 4 5 6 2 Fig. 28 Bent Wood Exoskeletons - .Joel Letkemann Fig. 29 Differentiated Wood Lattice Shell -Huang + Park page 60 system logic connection model Gridshell Gridshells are the most known construction where the bend- ing nature of wooden elements are utilized for an optimised structure. The gridshell structure derives its strength from its double curvature, in the same way that a fabric struc- ture derives strength from double curvature, but is con- structed of a grid or a lattice. Large span timber gridshells are commonly constructed by laying the laths on top of a sizeable temporary scaffolding in the wanted shape, which were removed in phases to let the laths settle into the desired curvature. A recent project example is the Savill Garden gridshell Another approach is initially laying out the main lath mem- bers flat in a regular square or rectangular lattice, and subsequently deforming this into the desired doubly curved form. This can be achieved by imagining to push the members up from the ground. Similar approach is used in the Mannheim Multihalle. Here Frei Otto used hanging models. Two different approaches are: 1. From wanted shape to grid and connections. 2. From planar grid to shape by moving of constraints. Gridshells might be made out of any elastic material, but is mostly made out of wood. The material properties, joints, grid and constraints are defining factors for the shape. Members need to be slender enough to bend, so in some cas- es, the structure has to be constructed in multiple layers. Gr id sh el l examples Isabella Realce Isabella Realce Isabella Realce page 61 references Fig. 30 Centre Pompidou, Metz - Shigeru Ban + Arup Fig. 31 The Savill Gardens - Glen Howells Architects Fig. 32 Centre Pompidou, Metz - Shigeru Ban + Arup Fig. 33 Gridshell Digital Tectonics - Smart Geometry ‘12 Fig. 34 Centre Pompidou, Metz - Shigeru Ban + Arup 1 2 3 4 5 2 4 1 3 5 page 62 Research 3.1.2 Part conclusion Many of the structural principles overlap in the catergorization. Many of these are closely related and combinations of them hold very interesting potentials. For instance combining bending + modules + network. Some of the referenced elements in the module part can be bend plate elements and worked in a more or less complicated network. Gridshells are mostly considered to construct a single three dimensional surface and sometimes offsets of this surface. A combination with principles from the more multidimensional network part, could prove to be an interesting kind of weave structure. Here elements can move in and out of the surface and start and end wherever, on or off the surface. The common thing for the presented structures are that they are different. Different from what is normally built and advanced in the looks of it, but pretty simple in the logic. Most of them are impossible or at least very time consuming to create without computationand scripting. Most examples are built as study-cases, casual pavilions, installations or furniture. The transformation from these principles to building elements, wall, floors, roofs etc. are very challenging, but also very exciting. It is tempting to put the conventional thought to the back for a while and think of buildings as multidimensional structures - not necessarily divided into floors, walls and roofs, but as a coherent environment. Isabella Realce Isabella Realce page 63 3 Fig. 35 Tripudio Bestia - Matthias Pliessnig Fig. 39 Lamella flock - CITA Fig. 36 Allotropic System - Nicholas Bruscia Fig. 40 Plasti(K) Pavilion - Marc Fornes THEVERYMANY Fig. 37 Centre Pompidou, Metz - Shigeru Ban + Arup Fig. 41 Dorian Pattern Facade - Khiem Nguyen Fig. 38 Resoloom - Peter Vikar Fig. 42 Migration - Matthias Pliessnig page 64 3.2 Gridshells From the initial research, the gridshell structure is chosen for further in- vestigation. The reason for choosing this principles is the direct utilization of bending in networks of slim regular elements. The thought is that when knowing how to construct more regular lattice gridshells, it is possible to combine this with some of the more random looking structures from the net- work part. This combination might end up somewhat like the pictures on the right hand side. The further investigation approach will look into parametric tools for form finding and the simuation of element behaviour. The first step is to setup an intelligent system that resembles the properties and geometry of real elements. Afterwards the elements will be put into networks, such as the lattice in the gridshell. Constraints in relation to connections and supports will be in- vestigated. A really important part of setting up such a system, is the ability to evaluate in terms of curvature, stresses, moment distribution etc. and in the end be able to translate the model to building elements. The prospects are that such a working method will enable the construction and analysis of complex geometry surfaces for whole building envelopes, roof, facades interiors etc. At the same time the thesis is that by setting up this scripting system, one will be able to create optimised structures, using similar approach as mentioned in chapter "2.3 Optimization" on page 30. Isabella Realce Isabella Realce Isabella Realce page 65 Fig. 43 Hello wood Fig. 44 Eclaireur Paris - Arne Quinze page 66 MODELLING page 67 [Interactive physics] Rhino Grasshopper Python Kangaroo page 68 4.1 Paper play 4.1.1 Physical investigation. Physical models are used for investigation in order to setup the needed script. By simple physical studies of shapes created by defor- mation, an idea of the behaviour is obtained. In the case of gridshells, it is interesting to look at what effect the initial grid has on the behaviour of the deformation and stability. Investigations include the shapes that is created from changing fix- ing points of the planar grid, the significance of connections and the deformation of individual elements. Another approach of the investigations is to lay a grid of strips on a already defined/built surface, fixing these at intersections on the surface and thereby finding the necessary grid configuration. The grid created by this method, is not necessarily planar. It is a way of constructing a predefined shape. This is particularly interesting for architectural projects in search of a certain shape.. When laying and interlocking strips on top of a surface, the relation- ship between element connections, material flexibility etc., creates 3-dimensional structure. This interesting effect that will be investi- gated later on. 4 | Modelling Isabella Realce Isabella Realce Isabella Realce page 69 Fig. 1 paperPLay - first physical test with regular paper. From grid to form. Fig. 2 paperPLay - First test: From form to grid. page 70 4.2 Theory Modelling 4.2.1 Compression members To create the deformations of the paper model, the members are subjected to external forces. The basic theory of this behaviour is that of compression members. A compression member - or a column - can be defined as a beam subjected to a compression force acting in the beam axis (local x-direction). Basically the theory can be divided into short columns and long columns. Short columns has the property that a column of the same cross section has the same load carrying capacity. If subjected to a bending moment, by e.g. eccentric loading, the stresses are found by Navier’s equation: Long columns or slender columns are characterized by being forced to de- flect when subjected to a sufficiently large normal force. If a simple linear elastic member is subjected to normal force N, that gives the deflection u(x). Moment equilibrium at any given point x is: For a member of linear elastic material with small deflections: Curvature κ can be defined as: Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 (1) (2) (3) (4) Isabella Realce Isabella Realce page 71 Which then gives the relation between moment and curvature: Local curvature of a spline geometry can also be found geometrically by: where R is the curvature radius. Equations (5) and (6) means that bending moment can be found by: Stresses can then be found by either: or by Navier (1): At the same time the critical Euler load can be found by putting (2) and (3) together: and rewriting this as a second order differential equation: Solving this gives: The critical load might be used to determine what force is needed for any deformation. This theory will be used later to find stresses, forces and mo- ments in the bend members. Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= NA Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 (5) (6) (7) (8) (9) (10) (11) (12) Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 Normal stresses : σc= N A Moment stresses : σm=± M W Combined stresses : σt= NA - MW σc= NA + MW M(x)=N*u(x) M(x)=-EI* d2u(x) dx2 d2u(x) dx2 =-κ ⇒κ=- M(x) EI κ= 1 R M(x)=κ*EI M(x)= 1 R *EI σ = E*ε = -yEκ σm=± M W EI* d2u(x) dx2 +N*u(x)=0 k2= N EI ⇒ d2u(x) dx2 +k2*u(x)=0 ⇒Nel= π2*EIls2 or page 72 4.3 Physical modelling 4.3.1 Particle system The digital modelling will be carried out using add-on Kangaroo. It allows the user to interact in real time with the model as the simulation is running. The Kangaroo engine is based on relaxation of a particle system. Particles are points or objects in a system that can have mass, position and velocity. They respond to forces, but have no spatial extent. Despite their simplicity, these particle systems can be set up to exhibit a wide range of physical behaviours. A system built by connecting particles with simple damped springs can resemble a wide variety of nonrigid structures. “Macroscopic properties of materials such as the behaviour in bending, shear and torsion can actually be seen as emergent* on a molecular level from simple interaction between pairs of particles” (Kangaroo Manual) This means that it is the interaction and behaviour of the millions of parti- cles/molecules that gives the overall bending behaviour that we know from a plate for example. It is clear that the amount of particles in these compu- tational simulations are vastly smaller than in the real world. With the right knowledge, real world behaviour can be translated into the distribution of points and springs, as well the internal relations between particle-particle and particle-springs. The results can be used for comparison between the two. This approach can give a good approximation of the real world physical behaviour. Even though this particle system has its limitations, it has the advantage of being fairly easy to understand and control. The theory behind the system just described, will be explained in the following step-by-step. * Developing / under development. Modelling Isabella Realce Isabella Realce Isabella Realce Isabella Realce page 73 4.3.2 Dynamic relaxation The aim of dynamic relaxation is to find a geometry where all forc- es in the system is in equilibrium. As mentioned in the introduction chapter, the likes of Gaudi and Frei Otto did the dynamic relaxation using hanging chains and weights, soap films etc. So by discretizing the continuum, meaning dividing an element into smaller pieces, the particle system is setup. In the example on Fig. 3 a steel rod is simulated. When a force is introduced to the system, an iterative process follows by simulating a pseudo-dynamic process in time, with each iteration based on an update of the geometry. The basis is to trace the motion of each node of a structure, step-by-step for small time increments, ∆t. Due to artificial damping, the structure can come to rest in static equilibrium. The first influence in the system is the desire of each part ele- ment - spring [si] - to reach its rest lenght. In most materials and in this example the rest lenght of [si] is the initial length as the material does not want to shrink. When particle [p5] is moved to towards left, the spring stiffness for [s4] introduces a force vector [v5] acting on particle [p4]. At the same time the stiffness of the spring [s3] between [p4] and [p3] introduces an opposite reaction force vector [v3] to [p4]. This then happens throughout the particle system - [p4] pushes on [p3], [p3] -> [p2], [p2] -> [p1] etc. To reach equilibrium each particle node moves, so that all vector forces acting on it is equal. If [p0] is fixed particles equally divide. p0 p1 p2 p3 p4 p4 p4 p4 p3 p5 s0 s1 s2 s3 s4 p5 rest length v5 v3 v5 v3 p4 v5 v3 Fig. 3 1D dynamic relaxation Fig. 4 Spring component page 74 Previously the system was only introduced to forces acting in line, lets call it planar force, this means that there are no out-of-plane forces in the system. This needs to be introduced in order to cause bending of the rod. This is one of the big differences from the real world to the idealized system. As soon as an out-of-plane force is introduced to the system, the particles move in different directions corresponding to the direction of the force vectors introduced. In this example; when moving [p5], the stiffness
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