report - tensinet...report ’working group meeting’ (22.05.2001) 3 2. working group engineering...

Report

Working Group Meeting, May 22nd 2001

TensiNet

Table of Contents Page

1. Introduction 2

2. Working Group Engineering 3

2.1 Discussion on the project data sheet 3

2.2 Discussion on the Design Guide 4

Tasks for the next WG-Meeting in October 5

3. Working Group Architecture 6

3.1 Discussion on the Design Guide Architecture 6

3.2 Preparation of proposals of one of the chapters 7

4. Working Group Material 8

4.1 Discussion on the Design Guide Architecture 8

4.2 Substitution of Ferrari 9

4.3 Discussion on the project data sheet 9

5. Afternoon Session 11

5.1 Next WG Meeting 18th , 19th October in Berlin 11

5.2 Presentations 11

5.3 WG Reports 11

5.4 Discussion 11

Annex I: Manual to use the Web page: www.tensinet.com 12

Annex II: Working Groups 17

Annex III: Discussion Document WG ENG by Mike Barnes 18

Annex IV: Design Guide ‘Permanent Fabric Design Guide’ by Marc Malinowski 26

Report 'Working Group Meeting' (22.05.2001)

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Report 'Working Group Meeting', Tuesday, May 22nd 2001 People present: Vrije Universiteit Brussel Prof. Marijke Mollaert (Co-ordinator) Jürgen Haase University of Nottingham Dr. John Chilton (Scientific Co-ordinator) University of Bath Prof. Michael Barnes (WG-Engineering Co-ordinator) Buro Happold Markus Balz Tentech Rogier Houtman Tensotech Matti Orpana Engineering System Int. Pierre de Kermel Club de la Structure Textile Marc Malinowski technet GmbH / TUB Prof. Lothar Gründig Universidad Politecnica de Prof. Juan Monjo Madrid Hopkins & Partners plc Bill Taylor Over Arup Brian Forster Rudi Scheuermann Institut Français du Textile et Dr. Guy Némoz (WG-Material Co-ordinator) de l'Habillement Laboratorium Blum Dr. Rainer Blum (Quality Co-ordinator) Heidrun Bögner Taconic Sean Seery ECCREDI Johan Vyncke (Dissemination Co-ordinator) University of Newcastle Dr. Peter Gosling (Observer) Dyneon Marc Brandon (Observer) Non-present: SL-Rasch Dr. Bodo Rasch (WG-Architecture Co-ordinator) (apologized) Canobbio Roberto Canobbio (apologized) Ceno Tec Wolfgang Rudorf-Witrin (apologized) Ferrari Françoise Fournier (quit the network)


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1. Introduction (Jürgen Haase) 10.00h Welcome Web page www.tensinet.com

• How to use • Password • Add a new person, company, project • More see ANNEX I

Presentation of TensiNet

• At 'Textile Roofs' (14th - 16th June) through a lecture of Jürgen Haase • TensiNet is co-host at 'Textile Roofs' which is the official workshop of TensiNet • Flyer (1st version)

TensiNet-partner FERRARI

• Ferrari wants to quit • Therefore reduced WG-MAT: Taconic is single company in this group • Substitution by Verseidag (A. Driesch)? VUB wrote a letter to invite him to this WG-

meeting, but no answer. • Sioen? • Wacker? • Further discussion in WG-MAT

Proposed distribution of partners in Working Groups for discussions later on (see ANNEX II): • WG-MAT • WG-ENG • WG-ARCH

Then the people split in only 2 groups, because members of WG-ARCH were not present yet.


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2. Working Group Engineering 2.1 Discussion on the project data sheet. This data sheet was distributed around the partners some days ago. It shall be used as a basic document for the database. Opinions: • Produce id-cards in order to flip quickly through it => to collect lots of buildings including

less information • Distinguish specific engineers: membrane engineer, structural engineer, special engineer (at

cable, column�, the acknowledgement of the special engineer can appear at the specific page of the data sheet)

• The author of the data sheet should be mentioned: filled in by � • Different cost categories: membrane, supporting structure, foundation, conditioning�

There were plenty more suggestions and additions which will be considered in the next version of the project data sheet. Then the original version will be available via the TensiNet web site. Wolfgang Rudorf-Witrin was not present at this meeting, but he sent his comments and remarks in advance by email: " To my opinion the data sheet is very (too) complex and detailed. The way the questions are given (for example: representative rope (or column) 1; asking for material, dimensions, length etc.) may lead to a confusion either in answering or in using that information unless a detailed set of drawings is attached which indicates all those points clearly. All over that - without knowing all facts behind the statical calculation (for example: dead loads for lighting or speaker system; special wind loads out of the configuration of surrounding buildings etc. dimensions of columns e.g., described for one building could lead to a misinterpretation for the next one. Such a situation would require more and more data, means that a complete set of technical drawings, the statical calculation and all written requirements for that special building have to be put in the data-box, which to my understanding would lead to a k.o.-criteria for a readable network. My proposal would be to maybe split the collected data as follows: a) Data of typical/and or all projects of interest in a short and clear form: as asked for in the "general information", added with some comments concerning material used (short description and reason for that decision). Each project should be accompanied by one or two overview sketches where the main elements (like ropes, columns etc.) are indicated by measurements, just to give a short impression. b) Data box of typical elements and details (seams, corners, edges, attachments, rope-fittings, connections "membrane to membrane"; "membrane to ropes" "Membrane to steel" "steel to ropes" and so on.....) maybe with links to typical projects to show these details in use. This details added with technical information concerning advantage and disadvantage, range of use... c) Language of forms of textile structures again with links to projects....


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This is only my idea to be discussed. To my feeling it could enable readers to come closer to solutions in a very short time rather then turn over hundreds of data pages." Project Presentations: Bill Taylor (photos): Roof in Nottingham Markus Balz (PowerPoint): Wind analysis at the shopping centre in Ashford Juan Monjo (slides): Roof at the coast in Portugal and new roof in Zaragoza (prestressed belt fixed to membrane => damage) 2.2 Discussion on the Design Guide Introduction and general requirements by Mike Barnes (see ANNEX III) General Remarks: - Description of Design Philosophy/Approach - Interaction between form/force - Help for proof engineer (in Germany etc.) - Difficult to separate material and engineering and architecture - Reduce safety factor (not load factor, but stress factor) - Tear propagation: cold climate -30º-40º => stiff material => easier damages - Curvature limitations? - Flat cladding - Terminolgy: TENSIONED FABRIC STRUCTURES - No inflated structures, but Design Guide should refer to IASS-Pneumatic structures - Danger: too much rules => too restrictive ; too less => not prescriptive enough Title: Engineering Design Guide on Tensioned Fabric Structures Chapter 1: Principles of Design • Example systems • Structural systems / support systems • Deformability under loading

Chapter 2: Design Philosophy (Basis for Design)

A limit stage approach for deformable structures • Stress factors, tear propagation / degradation • Seam strength • Temperature effects • Prestress level • Curvature • Stressing out concepts • Deformations • Stability of compression elements (e.g. arch systems)


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Chapter 3: Loading • Prestress • Wind • Snow • Distribution • Ponding / Sacking • Wind loading from EC 1

Chapter 4: Materials (WG ENG is writing this part and is giving afterwards to WG MAT!) • Stress-strain behaviour • Tear propagation • Real behaviour: what is physically happening in the fabric => practice • Stretch compensation • Seam strength • Test procedures

Chapter 5: Fabrication Details Chapter 6: Erection Procedures Chapter 7: Maintenance Annex: Glossary of terms Comment: "Try to use 80% from existing regulation and refer to." Conclusion: ______________________________________________________________________ Tasks for the next WG-Meeting in October: Brian Forster will write a proposal for Chapter 1 Brian Forster will write a proposal for Chapter 2 (with support of Mike Barnes) Markus Balz will write a proposal for Chapter 3 Mike Barnes will write a proposal for Chapter 4 Marc Malinowsky will write a proposal for Chapter 5 Matti Orpana will write a proposal for Chapter 6 Rogier Houtman will write a proposal for Chapter 7 ______________________________________________________________________ The Design Guide can be based on the existing document of Marc Malinowski (ANNEX IV)!


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3. Working Group Architecture Present: Vrije Universiteit Brussel Marijke Mollaert University of Nottingham John Chilton Universidad Politecnica de Madrid Juan Monjo Hopkins & Partners plc Bill Taylor Over Arup Rudi Scheuermann Apologized: SL-Rasch Bodo Rasch 3.1 Design Guide Architecture In most publications membrane structures have been treated as �structures�. But what else is important to design a building? The environmental aspects in terms of architecture are not clarified for textile roofs. The engineering contents will be oriented to �problem solving�, the architectural aspects to creativity and expression. Part of the Design Guide needs to address the professionals, another part should be oriented to people who have never worked with membranes. The Design guide should give inspiration and stimulate to exploit what is possible. A lot of examples should illustrate the different chapters. Chapter 1: Shape and pattern definition - Categorizing different shapes (synclastic / anticlastic, air-supported, etc.) - Visual appearance (internal /external, ornamental patterns, etc.) Chapter 2: Details - Categorizing details (Tensile Architecture p.88, ISIMEM learn CD, Bubner) - The architectural aspects Chapter 3: Environmental Aspects - Light, day lighting - Thermal performance, humidity - Ventilation - Acoustics Chapter 4: Sustainability [working title] - Ecological aspects - Embodied energy, cost in use Chapter 5: The Design Process - Describe the whole design process (CFD, thermal analysis) - Modelling techniques: physical modelling, computer modelling, etc.


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Chapter 6: Typical functions - Indicate which types are appropriate for specific functionalities The guide will contain at the end a technical dictionary (glossary) with both the typical terms and illustrating pictures (and a translation into other languages). 3.2 Like for the Working Group Engineering each partner will prepare a proposal for one

of the chapters for the next WG-Meeting in October.

1. Shape and pattern definition 2. Details 3. Environmental Aspects 4. Sustainability [working title] 5. The Design Process 6. Typical functions

- Marijke Mollaert - John Chilton - Juan Monjo - Bill Taylor - Rudi Scheuermann - Bodo Rasch


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4. Working Group Material Participants: G. Némoz J. Seery M. Brandon R. Blum H. Bögner

P. Gosling (afternoon) 4.1 Presentation of participants

Seery, Taconic: coater for PTFE-coated glass-fabrics,

interested in amelioration of 3 basic problems: comparative price, handle-ability (high bending resistance), welding difficulties, interested in solar and thermal transmission

Brandon, Dyneon: roots � 3 M, Höchst, Raw material supplier, producer of PTFE Némoz, IFTH: testing institute for fabrics, for architectural use mainly Polyester-

PVC Blum, Labor Dr.Blum: 3 material aspects should be distingueshed, their need for research:

o Strentgh, structural analysis o reflection (light, energy, thermal transmission), building

physics, o durability, maintenance


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4.2 Substitution of Ferrari

To find a possible partner a list of coaters has been created:

PVC Fluoropoly-mers Silicone Foils Taconic UK X Ferrari France X Verseidag Germany X X Sioen Belgium X Mehler Haku Germany X Sattler Austria X Cenotec Italy X Lantor? UK X Dickson USA X Novolfilm Patti Italy CS Interglas Germany X Sikatec Czech X Contitech Germany FPC X

To complete this list see IFAI brochure. Dr. Blum proposes to chose eventually one coater of PVC, one of PTFE (Taconic), one of elastomers and one producer of foils. He prefers Verseidag, Sioen, Mehler Haku, CS, (Contitech), in this order, and could make contact with Mehler and Sioen. Dr. Némoz proposes to extend the material working group and to create 3 groups: the core is built by the material working group members. Around this group could be another group, the so called �contacting group� consisting of coaters to which there will be held a closer contact. Around this group there could be a group of coaters with informal contact.

4.3 Discussion on the Project Data Sheet

The unit for strength should be taken over from the standard ISO 2411: N/5 cm. Mechanical values should be given as min. values Tear propagation: as mentioned here, it makes no sense mechanically, but could further be used for comparison. To be added to the list: coating adhesion (resistance to delamination), ISO 2411 To be added: Elongation at break


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Modulus of elasticity: Blum: there is a difference between pneumatically and mechanically prestressed structures, biaxial tests should be done, software for calculation of E-modulus on geometrical basis has been developped by Laboratory Dr. Blum, A range for the E-modulus should be given in the data sheet. Relaxation: should be also mentioned, purpose Dr. Blum: biaxial and uniaxial tests per batch Shear modulus, shear angle: should be given because it leads to different designs of structures covered by PVC- or PTFE-coated fabrics,

Comparison between biaxial and uniaxial tests

To be added: possible topcoats To be added: weave 1/1, 2/2 To be added: yarn´s properties/ definition of yarns, for identification, n° of filaments,

turns, tex Blum: Comments on materials, guideline for engineers to find suitable material for different applications, classification, values Némoz: information about cleansing possibilities Initial values: seam strength = fabric strength

Gosling/ engineer´s point of view: safety factors should be reduced, shear angle should be known.

To be added: Covering of nodds To be added: Ageing parameters

Radiation values: emissivity, absorbance in infrared range

Low-e-coatings in infrared and visible range, looking for translucent materials


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5. Afternoon session (all together) General 5.1 Next Working Group Meeting: Thursday, 18th and Friday, 19th October 2001 in BERLIN, Germany Host: TUB and technet GmbH, represented by Lothar Gründig, Dieter Ströbel and Björn Beckert Comment: Just ONE hotel for all partners! 5.2 Presentations Marc Malinowsky (slides): two projects in France (Vincennes, BOP Paris) Pierre de Kermel (PowerPoint): program LISA 5.3 Working Group Reports WG ENG (Mike Barnes): Comments: Feedback from statical bodies? No, but from ASCE possible. WG ARCH (Marijke Mollaert): Comments: Working Documents in the web? Advantage: Working doc is always updated available WG MAT (Guy Nemoz) 5.4 Discussion Fire resistance: Basis for the decision of architects or engineers? Kermel: DELIGHT has a database for materials. Transfer to TensiNet? Rasch is the owner. Properties of new material? Many producers do not know the mechanical properties of their products. If you use it, you have to ask someone who already worked with it. To receive the required information can take sometimes several days.


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ANNEX I: Manual to use the Web page: www.tensinet.com THIS WEBPAGE IS A DRAFT VERSION AND STILL UNDER CONSTRUCTION! These main items to use the TensiNet-web page will be explained in the following: 1. Introduction 2. login 3. add/edit/delete contact person 4. add/edit/delete company 5. add/edit/delete project 1 Introduction Screen of the homepage:


The menu is divided in 4 parts: - TensiNet includes the submenus Home and Contact. - About TensiNet includes the submenus More Info (More information about the objectives

and activities of the network TensiNet), Partners (coordinates of the contact person and a link to the homepage of the organisation) and Agenda (Time schedule of TensiNet meetings, only accessible for the partners)

- Tensile Structures includes the submenus Links (refer to companies and other organisations), Events (List of workshop, symposia, conferences related to tensile structures) and Forum ('tensile' chat box, only accessible if logged in)

- TensiNet Partners enables through Login to a variety of items 2 Login To login press the button Login in the TensiNet Partners menu item. The window, which is shown on the right, appears. Enter your first name (this item will be modified later on) and enter your password that you got at the first WG-meeting. Press the button LOGIN. Now some more options are enabled: - Open Agenda - Post a message in Forum New menu items in TensiNet Partners: - search company (search criteria: name a- search project (search criteria: name, co

material) - search person (search criteria: first nam

email) - logout New menu items in Admin: - add/edit/delete contact person in Admin - add/edit/delete company in Admin - Com- add/edit/delete project in Admin - Projec

nd/or country) untry and/or membrane

e, last name and/or

- Persons pany t

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3 Add/edit/delete contact person Options: Edit/delete existing person or Add new person When entering a new company the input of a contact person of this company is required. That means, first enter a contact person then a company represented by this contact person: Example: Add new person First name, Surname, Email, Phone and Fax number Optional input: Company Function, TensiNet Function (not necessary), Homepage (e.g.: http://www.tensinet.com) Press the Add-Button The option search person looking for 'Marc' will produce such a result, which is visible for the user. Click on the email-name effects an automatic email to Marc Brandon. Click on the company-name is linked to the page company details.

REMARK: If your browser shows an unchanged page, press 'REFRESH' at your browser after editing, deleting or adding!

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4 Add/edit/delete company Options: Edit/delete existing company or Add new company When entering a new project the input of companies involved is required. That means, first enter the companies then the project: Example: Add new company Company Info: Name, Homepage, Function (Engineer, Architect, Producer or Constructor) and Contact Person Visiting address: Street, Nr, PO Box, City, Postal Code, Country (all EC-countries), phone and fax nr Just in case the contact address differs from the visiting address: Press the Add-Button

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5 Add/edit/delete project Options: Edit/delete existing project or Add new project Example: Add new project Project info: Name, 1 picture, begin date and end date of construction, max. span in x- and y-direction, max. height, covered surface, membranematerial and comments Involved Companies: Architect, Engineer, Producer and Constructor which are already defined in the menu add/edit company.

Project Location:

Press the Add-Button

REMARK: This is a very draft version and only contains elementary data. During the next meetings the data sheet will be extended to a valuable and user-friendly database.
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ANNEX II: Working Groups

Marijke Mollaert

WG Engineering Michael Barnes Dieter Ströbel Paul Westbury Rogier Houtman Matti Orpana Eberhard Haug Marc Malinowski Wolfgang Rudorf-WitrinBrian Forster Roberto Canobbio Björn Beckert Lothar Gründig Markus Balz Peter Gosling

Jürgen Haase

Italic: not present at the WG meeting

WG Architecture Bodo Rasch John Chilton Rudi Scheuermann Bill Taylor Juan Monjo-Carrio

WG Material Guy Némoz Rainer Blum Heidrun BögnerSean Seery Marc Brandon

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ANNEX III: TENSINET MEETING 22 MAY 2001 W.G. For Engineering Design: Discussion Document

The purpose of the meeting is to consider objectives / intended outcomes for the Working Group. At the previous meeting it was proposed that our main objective was to produce a Design Guide which would not have the status of a Code of Practice but would contain specifications / guidelines for good practice proposed and agreed by leading Consultants and Fabricators in the field, with additions by research groups relating to aspects such as appropriate methods of form-finding, analysis and patterning, and the modelling of materials properties, tear resistance, stretch compensations and test procedures. A Design Guide can be general - intended for a wide range of designers and consultants in the industry - and cover a range of issues from historical development and design principles to typical fabrication details and stressing out procedures; or it can be specific - intended for specialist designers, consultants and fabricators - and which, although not a Code of Practice, might be referred to by Regulatory Authorities and used to specify appropriate standards. There are several examples of general design guides and the contents lists of some of these (1993, 1996, 1999) are appended. The most recent of these, by Craig Huntington, is a good text book for either Architects or Engineers in general practice who may wish to develop some specialised knowledge of tensioned fabric structures). However, in the context of standards specifications there are few (if any) wholly satisfactory documents. Perhaps it is much easier for a single author or small group to produce a general design guide which covers principles and example applications, than one which is prescriptive and/or restrictive. Yet the latter, relating to procedures and standards which should be met, is probably most needed by the specialist industry. An example concerning appropriate procedures can serve to highlight difficulties relating to conventional Codes of Practice, even at the most fundamental level of design philosophy: Is limit state design appropriate and in what form? - Restrictions on deformations, and certainly normally accepted levels, are rarely appropriate in the design of tensile structures - they are intended to deform to accommodate to the loading- but deformations are crucial in relation to aspects such as ponding in shallow surface regions. And design to permissible stress conditions is usually more appropriate than load factoring: if a fabric structure is required to carry its full design loading in the presence of small tears, or imperfections at details, then a minimum factor of 4.5 on virgin fabric strength may be required, and substantially more in practice to allow for degradation. But what should be the appropriate factors? - 6 or 8 - and for what types of fabric? The notion of load factoring in this context is inappropriate; yet for supporting structures subject to compression (e.g. arches) load factoring may be essential to comply with Codes for acceptable factors of safety for stability. And another aspect of security concerns the hierarchy of components - for example the stability of heavy steel support systems in the event of failure of light membrane regions. All these limited example aspects of tensile structures concern design approach, which is fundamental to standards. Probably the job of the Working Group is to commence with agree an introductory section on appropriate design approaches which is not unduly restrictive. Subsequent sections of a Design Guide would cover aspects such as loadings, material properties, appropriate details etc.. The meeting today should agree the headings and sub-headings for these sections (with perhaps the appended contents lists for review), and should preferably apportion tasks to delegates.


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FABRIC STRUCTURES By MARC MALINOWSKY (1993) 1. Introduction 1.1 Brief history 1.2 Development during the last 40 years 1.3 Development of the constituent characteristics 1.4 Computer contributions 1.5 Main motivations 2. Membranes 2.1 Definitions 2.2 Constitution 2.3 Properties 2.4 Evolutions and market trends 3. Elements for fabrics tensioning 3.1 Frames 3.2 Secondary elements 4. Static principles - Topology 4.1 Load bearing capacity principles of the fabrics 4.2 Advantages and disadvantages various types 5. Modelling and calculations 5.1 Mechanical behaviour and theoretical basis 5.2 Calculation methodology 5.3 Form finding 5.4 Structure calculations under external loads 5.5 Cutting pattern determination 5.6 General investigations on the Chinese hat 6. Analysis of other technical aspects 6.1 Pattern cutting and assembly 6.2 Pretension of fabrics 6.3 Precipitation drainage 6.4 Illumination 6.5 Thermic and condensation 6.6 Fire behaviour 6.7 Cleaning and maintenance 7. Regulations 7.1 Existing regulations 7.2 Proposals for technique codification 8. Conclusions


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TENSIONED FABRIC STRUCTURES: A Practical Introduction; ASCE 1996.

Table of Contents A Practical Introduction to Tensioned Fabric Structures

Introduction

Chapter 1. History of Fabric Structures 1.1 Traditional Tent Forms 1.2 Air Structures 1.3 Cable Nets 1.4 Tensioned Fabric Structures 1.5 Cable Domes 1.6 Convertible Roof

Chapter 2. Design and Construction Processes 2.1 Conventional Organization of the Design and Construction Team 2.2 Design/Build Construction 2.3 Organization of the Design and Construction Team for Tensioned Fabric Structures 2.4 Building Department Interface 2.5 Conclusions

Chapter 3. Performance Considerations 3.1 Loads and Climate 3.2 Availability of Materials and Labor 3.3 Spatial Considerations 3.4 Aesthetics 3.5 Fire Safety 3.6 Energy Use and Lighting 3.7 Acoustic Performance 3.8 Maintenance, Durability, and Inspection 3.9 Cost Issues

Chapter 4. Characteristics of Fabrics 4.1 General 4.2 Fibres 4.2.1 Nylon 4.2.2 Polyester 4.2.3 Glass 4.2.4 Aramids 4.3 Coatings


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4.3.1 polyvinyl chloride (PVC) 4.3.2 Polytetrafluoroethylene (PTFE) 4.3.3 Silicone 4.3.4 Toppings 4.4 The Behaviour of Architectural Fabrics 4.4.1 Damage from Folding or Tearing 4.4.2 Tensile Strength 4.4.3 Stretching and Dimensional Stability 4.4.4 Resistance to Chemical and Ultraviolet Attack 4.4.5 Fire Resistance

Chapter 5. Form Determination 5.1 Basic Design Principles 5.1.1 Tensile Behaviour 5.1.2 Geometric Classification 5.1.3 Equilibrium Considerations 5.2 Forms 5.2.1 Conic 5.2.2 Saddle 5.2.3 Undulating 5.2.4 Hybrid 5.3 Physical Models 5.3.1 Soap and Liquid Plastic Films 5.3.2 Stretchy Fabric 5.3.3 Mesh 5.3.4 Detail Studies 5.3.5 Construction Studies 5.4 Simple Preliminary Analysis 5.5 Computer Analysis 5.5.1 Non-Linear Displacement 5.5.2 Dynamic Relaxation 5.5.3 Force Density

Chapter 6. Analysis and Design 6.1 Codes and Standards 6.2 Applied Loads 6.3 Design Parameters 6.4 Analysis Techniques 6.5 System Components 6.5.1 Fabric 6.5.2 Cables 6.5.3 Beams, Columns, Masts, and Rings 6.5.4 Foundations


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Chapter 7. Connections 7.1 General 7.2 Fabric-to-Fabric 7.3 Fabric-to-Rigid Edge 7.4 Fabric-to-Cable 7.5 Cable-to-Cable 7.6 Cable-to-Mast 7.7 Cable to Rigid Edge -or Anchorage

Chapter 8. Fabrication and Construction 8.1 Fabric Patterning 8.2 Fabric Handling 8.3 Installation 8.4 Special Considerations Appendix: Glossary of Terms Index


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THE TENSIONED FABRIC ROOF Craig Huntington 1999 Table of Contents Acknowledgements Preface Introduction: The Tensioned Fabric Roof 0.1 Introduction 0.2 A Layman's Fascination and an Architect's Perplexity 0.3 The Architect�s and the Engineer's Appreciation of Tensioned Fabric structures

References Chapter 1 Elements of Form and Design 1.1 Introduction 1.2 Principles of Design 1.3 Generating Anti-Classic Shapes 1.4 The Art of Design

References Chapter 2 Tensioned Fabric Structural Systems 2.1 Introduction 2.2 Tents 2.3 Suspended Roofs 2.4 Ridge and Valley Systems 2.5 Cantilever Canopies 2.6 Arch Systems 2.7 Air Supported Roofs 2.8 Air inflated Lenses 2.9 Cable Domes 2.10 Cable Nets

References Chapter 3 Materials 3.1 Introduction 3.2 Fabric Performance Parameters 3.3 PVC-Coated Polyester 3.4 PTFE-Coated Fibreglass 3.5 Silicone-Coated Fibreglass 3.6 Films 3.7 Meshes, Knits and Other Alternative Materials 3.8 Cables and Fittings


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3.9 Supporting Elements References

Chapter 4 Form Finding and Analysis 4.1 Introduction 4.2 Non-Numerical Shaping Techniques 4.3 Elementary Analytical Procedures 4.4 Computerized Techniques 4.5 Design Evaluation and Refinement 4.6 Loading 4.7 The Fruits of Accurate Shaping and Stressing 4.8 Enriching the Vocabulary of Form

References Chapter 5 Connections and-Detailing 5.1 Introduction 5.2 Fabric Terminations 5.3 Cable Terminations 5.4 Mast Top Connections 5.5 Mast Base Connections 5.6 Pretensioning Mechanisms

References Chapter 6 Fabrication and Erection 6.1 Introduction 6.2 Fabric and Seam Selection 6.3 Patterning 6.4 Cutting and Seaming 6.5 Fabrication of Ancillary Elements 6.6 Layout 6.7 Erection 6.8 Coordination With Other Phases of Construction 6.9 Maintenance

References Chapter 7 Non-Structural Performance Parameters 7.1 Introduction 7.2 Day lighting 7.3 Energy Use 7.4 Adverse Weather Conditions 7.5 Acoustics 7.6 Fire Safety

References


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Chapter 8 The Contemporary Fabric Structures Industry 8.1 Introduction 8.2 Conventional organization of the Design and Construction Team 8.3 Organization of the Design and Construction Team for Tensioned Fabric Structures 8.4 Conclusions


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ANNEX IV: PERMANENT TENSILE FABRIC DESIGN GUIDE

Final version of 20/02/1997 Paris, La Defense, 18/06/1997

J.-P. Biger

Translated from French by Marc Malinowsky The following editing board has achieved the present permanent tensile fabric design guide: M. BIGER BUREAU VERITAS WRITER M. FERRARI TISSAGES FERRARI M. LE CHAFFOTEC SOCOTEC M. QUOST AGIBAT-MTI M. KRIMM SOCOTEC Mrs QUEFFELEC GROUPE ARCORA M.SEGUIN TISSAGES FERRARI Annex B - Life expectancy was written by M.BAEGERT OF C.E.P. (Not available here) The first draft of this issue, dated January 9, 1995 was checked through professionals. The second draft was revised on October 22, 1996 by a reading board composed of: 1 OBJECTIVE OF THE DESIGN GUIDE The objective of this guide is to define and collect prescriptions that can apply to permanent tensile fabric design, in an appropriate way for their use in the building industry. These prescriptions refer to the stability of these constructions together with their life expectancy. Appendix B summarizes the results of a study devoted to the life expectancy of tensile membrane covers. The word "cover" is to be taken in the sense of overall cladding. Regulations regarding the waterproofing of these covers do not concern the present document. Prescriptions concerning the people's security can be found in specialized regulations, and are not the objective of the present document. Please note: Fabrication and erection of tensile structures design guide are presently in the process of being written. While awaiting the publication of this second part, the use of the present document should be particularly cautious. 1.1 Field of application The present guide applies to permanent tensile fabric requiring a saddle shape and initial pre- stressing.


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For instance, this guide refers to realisations such as: B.O.P. of Roissy-Charles-de-Gaulle Zenith of Montpellier Basel-Mulhouse toll station Bordeaux Exposition hall Massy T.G.V. Railway station This also concerns more usual buildings such as canopies, swimming pools, or sporting halls. Retractable structures are considered as permanent. Realizations with flat fabric or with a single curvature are not concerned with the present guide. The double inverted curvature has indeed a stabilizing effect on the fabrics of the covers, which increases their life expectancy. Removable or itinerant structures are not concerned with the present guide. See in this respect the security rules applying to Big Tops, Tent and Itinerant Structures (C.T.S. types). Inflatable covers (whether with single curvature or with double curvatures in the same direction) are not concerned with the present guide. See in this respect the safety regulations applying to Outdoors installations and Inflatable Structures (P.A. types, S.G). Blinds, awnings and similar installations are excluded from the field of application of the present guide. 1.2 Content The present guide defines the composition of permanent fabric tensile structures; it specifies the nature of materials used for their construction; it settles design and calculation regulations; it describes execution documents and quotes the check list to be undertaken for fabrication, erection, delivery, and servicing. 2 PERMANENT TENSILE FABRIC STRUCTURES COMPOSITION Permanent tensile fabric structures include: � Tensile fabric � Tensioning devices � Main structure � Bearings � Anchorage 2.1 Membrane cover The membrane cover is specified by its shape, its surface, its pre-stressing, the characteristics of the fabric used, as well as the patterning, the welding and the edges.


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2.2 Tensioning devices Tensioning devices include items fixing the fabric to its support. This means roping, edge cables, fixing profiles, comers, turnbuckles, shackles, and so on. 2.3 Main structure The main structure, self stable, holds up the textile membrane cover through the superstructure. It thus constitutes the fixed or quasi-fixed points on which the membrane is stretched and transmits to the bearings the reactions resulting from the loads acting on this membrane. 2.4 Bearings and Fixings Bearings and Anchorages include the works linking the main structure, the tensioning devices, and the ground. 3 MATERIAL The mechanical characteristics of materials and tensioning devices have to be defined. The mechanical characteristics of delivered materials must fit with the calculated values. 3.1 Fabric The characteristics of the fabrics, and when necessary, their type, must be specified according to the following specifications, together with those found in Appendix A. 3.1.1 Characteristics � nature of fabric (material), � mass of the support and total mass of the composite (g/m 2) (ref. NF-EN 22286,2286-2), � nature of the coating of the inner and outer faces, � weave (ref. NF G 07 155), � instantaneous average uni-axial rupture stress (N/5cm) according to warp and weft. (NF G 37 103), � Elastic elongation modulus (see Appendix A), � bi-axial stress / stress curves in the ratios I / 1, I / 2, 2 / I (see Appendix A), � Poisson's coefficient (see Appendix A), � resistance to a starting rip (N) (trapezium) according to warp and weft (PR-EN 1875-3), � adherence (NI 5cm) (NF G 37 107), � welding capacity at 65°C (N/5cm), � Fire resistance (both sides) (index) (NF P 92 507). Table 1 : Types of fabric PES/PVC 3.1.2 Types of Fabric The polyester fabric PVC coated is classified by types, according to their mechanical resistance, their weight, their adherence, the minimal width of the welds, the resistance of the welding at 65'C, and their fire resistance.


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3.2 Steel � the usable steels are the ones showing the standards listed in Appendix B, P 22 31 11 norm (EC3 -DAN) parts B 1 and B2 � steels to be galvanized should answer to the prescriptions of norm NF-A35-503 � steel cables must correspond to the norm NFA 47 200. 3.3 Aluminium Characteristics of aluminium combinations must agree with the requirements of DTU P21 702 (AL Rules) and P22 202 (DTU 32.2) 3.4 Wood Characteristics of woods used must agree with the requirements of DTU P21 701 CB 71 Rules) and NF B 5 200 1. 3.5 Concrete Characteristics of concrete used must agree with the requirements of DTU P 18 702 (BAEL 91) and DTU P 18 201. 3.6 Other material Where other material is used, the constructor must justify its mechanical characteristics and its durability. 4 DESIGN The permanent textile covered buildings must be conceived so as to meet the specific design criteria applicable to the cover membrane, the main structure and the tensioning devices. 4.1 Design of the cover membrane The design criteria of cover membrane concern the shape, the pre-stress, the curvature, the edge slope, the splitting and the limitations of use. 4.2 Shape The shape of the textile membrane cover must be a double inverted curvature surface. It must respect the criteria limiting the main curvature radii of the membranes; failing this, stabilizing shape devices can be used. The main curvature radii of the membranes must not exceed 35 in when under pre-stress. The valley cables, the ridge cables, the ridgepole cables are indeed devices for shape stabilization that can be considered. 4.1.2 Pre-stress For each construction, the textile cover membranes must be subjected to an initial pre-stress at least equal to 1.5 kN/m.


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4.1.3 Edge slopes The edge slopes of the textile cover membranes must be sufficient to allow the outflow of the rainwater. When positive, the edge slope of the textile cover membranes must not be less than 20% under pre-stressed equilibrium. 4.1.4 Splitting The surface of a continuous element of cover, limited by its rigid edges or edge cables should not exceed 500 m2 plane projection, except when particularly justified (Reinforcements). The projected surface of cover elements including sliding intermediate stays should not be over 400 m2. This concerns covers with multiple bays.

(PHOTO) Printing works Raffy-Pack - Marolles-en-Brie (France) 4.1.5 Limitation of use The use of type I PVC coated polyester fabric is admissible for elementary covered surfaces under 30 m2 in plane projection. The use of type II, III, IV or V PVC coated polyester fabric is compulsory for elementary covered surfaces over 30 m2 in plane projection. 4.2 EDGE CABLES The radius of curvature of the edge cables should not be over 25 m. 4.3 Main structure The carrier structure must be stable in the absence of the membrane cover. 5 CALCULATION Calculation of the textile cover works must meet the following requirements concerning behaviour hypotheses, calculation methods, actions, combinations and dimensioning criteria. 5.1 Behaviour hypotheses This concerns mechanical and geometrical non-linearity, and displacement of the main structure. 5.1.1 Mechanical non linearity It is not necessary to consider the mechanical non-linearity of materials in elongation and resistance calculation by using the elasticity modulus defined according to prescriptions of Appendix A One should take into account the non-linearity of the material when defining the patterning. 5.1.2 Geometrical non-linearity


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When calculating one must take into account the geometrical non-linear behaviour of the cover membrane. 5.1.3 Displacement of the main structure When calculating one must take into account the influence of the displacement of the main structure. According to its relative importance it can either be neglected or incorporated into the calculation. 5.2 Calculation methods of the cover membranes 5.2.1 Definition of the initial shape The shape of the works under pre-stress must be defined by an appropriate method. Example: Minimum surface, density forces, splines. 5.2.2 Calculation by independent strips Cover membranes with a simple shape and with principal curvature radius under 20 m and a surface less than 250 m2 can be calculated in independent strips, provided the influence of the displacement of the support is negligible. Pattern drawings must be set in accordance with the equilibrium shape under pre-stress. 5.2.3 Finite elements and cable nets Membrane covers with a curvature radius over 20 m, or with a surface over 250 m2, or with a complex shape must be calculated by finite elements or by cable nets. The method used must be able to define the initial equilibrium shape under pre-stress. 5.3 Actions to be taken into account The minimal hypotheses of loads and overloads to be taken are as follows: 5.3.1 Permanent loads They include the self-weight of the structure, the fabric and the permanent equipment. 5.3.2 Pre-stress The initial stresses of the fabric and the cables must be defined. Their nominal values and their variations (creep, re-stressing) must be taken into account. 5.3.3 Exploitation Overloads When overloads in operation specific to the building exist, they must be mentioned among the calculation hypotheses. These overloads can be increased to take into account possible dynamic effects. 5.3.4 Weather overloads • Snow


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The snow overload to be taken into account, and its distribution, are defined by rules 65 (DTU P 06 002) and snow map N 84 (DTU P 06 006). In some cases, adaptations concerning the distribution of snow on surfaces with a double curvature may prove necessary. • Wind

The pressure of wind to be taken into account is defined by rules NV 65 (DTU P 06 002). The stress coefficients can be taken from rules NV 65, or determined by experimental means (wind tunnel tests), they must be subjected to a detailed definition. 5.3.5 Minimal lump overload In areas not subjected to snow overloads, a minimal lump overload of 30 daN/m, uniformly distributed, must nevertheless be considered. 5.3.6 Replacement of a fabric part The case where one part of the fabric should be replaced must be taken into account in the calculation of the main support framework. 5.3.7 Subsidence of supports The case of subsidence of supports must be considered 5.3.8 Temperature The case of temperature variations must be considered. 5.4 Combination of actions The geometrical non-linear behaviour of textile cover membranes must be taken into account. In order to do this, the combinations are to be made on the actions and not on the stresses. This is diverging from the usual practice for metal, wood, or concrete structures, which show a linear behaviour. 5.5 Calculation criteria The calculation criteria specific to membrane, to superstructure, to bearer structure and to anchorage must be met. 5.5.1 Membrane calculation criteria This concerns the equilibrium under pre-stress, of the shape stability and of the calculation stress. • Equilibrium under pre-stress

The equilibrium of the membrane under pre-stress must be demonstrated. • Shape stability

For covered buildings over 250 m2, or with a radius over 20 meters for the main curvature, or with a complex shape:


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� The absence of curvature inversion under combinations must be verified: o self weight + pre-stress + normal snow o self weight + pre-stress + normal wind

In this last case, if the criterion if not met, it must be demonstrated that the fabric dos slacken neither in warp nor in weft. � it must be verified that the slackened areas do not exceed 20% of the total surface for the combinations :

o self weight + pre-stress + extreme climatic load � the absence of slacks susceptible of gathering and accumulating rainwater must be verified under the combination:

o self weight + pre-stress - extreme snow • Membrane Stresses of calculation and dimensioning

The action combinations and balance coefficients that should be kept in mind for actions other than the self weight of the membrane, the pre-stress, the minimal lump load and the replacement of a fabric element, are those defined by the rules; inherent to the material of the main structure in the following paragraphs: 1.21 and 1.23 of rules CM 66 (DTU P 22701) 3.32 and 3.34 of rules AL 76 (DTU P 22702) 1.21 and 1.22 of rules CB 71 (DTU P 21701) � The self-weight and the pre-stress of the fabric must be incorporated to these combinations; the balance coefficient applicable to the self-weight of the fabric and the safety factors applicable to the fabric pre-stress must be equal to 1. � For the case of the minimal lump overload the safety factor is equal to 1. � In case of replacement of a fabric element, the pre-stress of the neighbouring elements and the self-weight, balanced as indicated above, are to be combined without the climatic overloads. It is admitted that the concrete foundation are dimensioned on the basis of actions on supports resulting from the preceding combinations considered as ELU (Ultimate State of Use) In the present state of ruling evolution, the definition of combinations of actions more specific to calculation of the fabric's resistance can only be considered as supplements to the combinations defined by the rules inherent to the materials of the supports. For each combination of balanced actions thus defined the following dimensioning ratio must be verified:

Tc ≤ TD Where:

TC: stress of membrane calculation in warp or weft TD: stress of membrane dimensioning

The stress of membrane dimensioning is given in different ways depending on whether standard parts or areas of tensioning devices to the main structure.


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• Dimensioning stress for standard parts. For standard parts (full fabric) the dimensioning stress of the fabric is given by TD = kq · ke · Trm / γt Where:

TD: dimensioning stress of membrane in warp or weft Trm: mean resistance to uni-axial traction, in warp or weft kq: factor of membrane quality ke: factor of scale depending on the surface of the cover element γt: safety coefficient

The factor of membrane quality if given by:

kq = Min ( kt, ks ) Where:

kt: factor of fabric quality ks: factor of welding quality

The factor of fabric quality kt and the factor of welding quality ks are respectively taken as equal to 1 when their mechanical characteristics have been submitted to manufacturing auto- testing, ratified by an external laboratory, or when its manufacture is certified ISO 9002. It is taken as equal to 0.8 in the opposite case. The scale factor ke is given according to the surface in sqm of the textile cover elements by the algebraic expressions (4a and 4b) or in simplified form in Table 2:

ke = 1 for S < 50 m2 (4a) ke =(50/S)1/15 for S >50 m2 (4b)

Table 2 The lump scale factor takes into account the increase of risk of a critical defect When the surface increases. The security factor γt is determined according to the conditions of exposition of the construction to pollution and according to the nature of the canvas. It is taken as equal to the values shown in Table 3. The strong pollution in Table 3 corresponds to a pollution caused by industrial smokes or exhaust fumes when traffic is heavy.

Table 3 Page 10


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• Dimensioning stress of force concentration areas The dimensioning stress of force concentration areas (edges, node) is given by:

TDloc = ( kq · neff · Tm ) / γtloc (5) Where:

kq: quality factor of the fabric as defined above neff: number of folds efficient in case of reinforcements, taken to be equal to I in the

absence of reinforcements Trm: mean uni axial resistance, in warp or weft γtloc: local security coefficient taken as equal to 5.

• Efficiency of reinforcements

Reinforcements must be made out of basic fabric. For canvas made out of glass fibres, only one reinforcement is admitted. The resistance increase due to the presence of reinforcements must be appreciated as follows: Resistance of (fabric + 1 reinforcement) : neff = 1.9 Resistance of (fabric + 2 reinforcements): neff = 2.6 Resistance of (fabric + 3 reinforcements): neff = 3.1 Resistance of (fabric + 4 reinforcements): neff = 3.4 • Edges

The mechanical resistance of edges must be justified with reference to trials; the security coefficient in relation to extreme combinations must be at least equal to 2.5 5.5.1 Tensioning devices The strength of the constitutive elements of the tensioning devices (cables, turnbuckles, corners...) must be justified with reference to experimental breaking loads guaranteed by the manufacturers of these elements. Failing specific regulations the security coefficient in connection with breakage to be taken into account to justify the elements under the effect of balanced loads is γa = 2 for the cables and γa = 2.5 for the other parts. 5.5.2 Main structure The elements of the structure will be justified taking into account the non-linearity of the fabric, according to their own rules. The case of a lump overload and of the replacement of a fabric element must be considered as complement. • Steel structure

With reference to DTU P 22 701 5 (CM 66 Regulation) • Aluminium structure


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With reference to DTU P 22 702 (AL 76 Regulation) • Wooden structures

With reference to DTU P 22 701 (CB 71 Regulation) 5.6 Anchorage Anchorage must be justified. 5.7 Contents of the calculation note The membrane, the main structure and the anchorages must be the object of calculation notes. The calculation note of the membrane must include the justification of:

• load hypotheses • modelization • initial shape, stability of shape and dimensioning of the fabric • dimensioning of the tensioning devices.

This note of calculations must include a table of taking down the loads on the supports. Experimental justifications may be admitted; in this case the report of the reference tests must be supplied. 5.8 Results and explanatory documents for the tests The tests for a construction to be put into use must be considered as an identification test confirming the validity of the calculation hypotheses and the quality of execution. The loading test of a construction is not intended to appreciate the degree of true security with respect to overload. It cannot, therefore be considered as a justification of the structure dimensioning. Tests must:

� either be made by an approved laboratory � or be made in the presence of an approved control agency.

The tests intended to demonstrate the strength of an element, of a sub-assembly, of a connection,... must be made until the samples are totally ruined. One can usefully refer to Appendix Y of EC3. 6 GUIDE AND EXECUTION PLANS The execution file relating to the construction must include plans concerning the membrane, the main structure and the anchorage.


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The membrane execution drawings must include: • The guide plan of the textile cover, defining the geometry, the curvature, the attachment

points. The nature of the fabric and the pre-stress value are indicated on this drawing. • The guide plan of the carrier structure. The components are located on this plan. It also

shows the values of pre-stress to apply to the cables of the main structure. • The detailing plans of the fabric with definition of the strips and of the welding. The

plans for the tensioning devices. • Justifications of the manufacturing quality of the fabric and of the membrane figuring

(results of manufacturing controls, opinion of the laboratory keeping track of the work, certification sheet ISO 9002).

The execution plans of the main structure and the anchorage execution plans must include a guide plan of the cover. 7 VERIFICATIONS AND MAINTENANCE � A verification of the stress of the fabric must be carried out during the construction. � A visit in order to check the stress must be made within 6 months. � Checking visits are desirable at regular intervals. � A recurring cleaning of the membrane cover is desirable (see Appendix B)

Final version of 20/02/1997 Paris, La Defense, 18/06/1997

J.-P. Biger

Photo: Gerland -North turning 3/4 front view