novel structural skins€¦ · temperature and burning speed > membrane melts > opening in...

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Brussels, 07 October 2014

COST Action TU1303

Novel Structural Skins

WG5 Meeting Minutes

Date: 30 September (10:00 – 13:00) Venue: Vrije Universiteit Brussel Pleinlaan 2 B-1050 Brussels Marijke Mollaert, Jimmy Colliers

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Content List of participants ........................................................................................................................................ 2 Agenda ......................................................................................................................................................... 3 1. MOU ..................................................................................................................................................... 3 2. SaP report: the last contributions ......................................................................................................... 3 3. Existing research in context of the SaP report, and future Eurocodes ................................................ 5 4. Following the SaP report: to advance on the key points ...................................................................... 5 5. Reliability analysis, calibration ............................................................................................................. 5 6. Conclusions .......................................................................................................................................... 6

List of participants Surname First name Country Present Apology Absent Bilginoglu Faruk DE x Bletzinger Kai-Uwe DE x Colliers Jimmy BE x Gerhold Sebastian DE x Gibson Nick UK x Gosling Peter UK x Heyse Pieter BE x Houtman Rogier NL x Lombardi Stefania IT x Malinowsky Marc FR x Marion Jean-Marc FR x Michalski Alexander DE x Mollaert Marijke BE x Novati Giorgio IT x Orr John UK x Puystiens Silke BE x Sastre Ramon ES x Sahnoune Farid FR x Saxe Klaus DE x Schoefs Franck FR x Siemens Peter DE x Stimpfle Bernd DE x Stranghoener Nathalie DE x Tanev Vatyu BG x Thomas Jean-Christophe FR x Uhlemann Jorg DE x Van Craenenbroeck Maarten BE x Van Langhenhove Lieva BE x Wille Joost BE x Zellinger Manfred AT x

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Agenda 1. MOU 2. SaP report: the last contributions 3. Existing research in context of the SaP report, and future Eurocodes 4. SaP Report: to advance on the key-points 5. Reliability analysis, calibration 6. Conclusion

1. MOU Overview of tasks and deliverables, see hand-out of the PowerPoint presentation 140929_Brussels_WG5_presentation.pdf (http://www.novelstructuralskins.eu/wp-content/uploads/documents/Brussels2014/140930_Brussels_WG5_presentation.pdf)

2. SaP report: the last contributions Expand the structural confidence and use in city à Work and promotion Scientific and Policy Report à State-of-the-art à Base for Eurocode, should contain a harmonized view of technical aspects Round Robin Exercise I (P. Gosling) à Heterogeneous results à What is going on? + Round Robin exercise II: Bi-axial testing Wind: Contribution from Alex Michalski for the SaP-‐report

- The pressure coefficients for ‘regular shapes’ given in the codes are not applicable - All engineers designing and analysing membrane structures have the same problem

à Round Robin exercise WIND Pressure coefficients for basic shapes

à Table of basic shapes (see Round Robin exercise III document) à New cp-values for typical membrane geometries would be better than the current use of cp-values

for conventional building typologies à Open and enclosed state: completely different aerodynamics: if open, flow can go below the

canopy à Different kind of inflow conditions (laminar ó boundary layer) à cfr. Cube Testing (the Wind

Engineering Society – WES (UK) did a Round Robin exercise on a cubic building shape), different vortices and pressure coefficients

à Scale: affects the position in boundary layer à Effect of the edges? à Fast change of wind à reaction of the flexible membrane changes? WE DON’T KNOW!!! à Mean, peak values?

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à If data has to be used for the Eurocode: standardized tests are required, with a specific wind profile;

need for experienced wind tunnel testing Current Problem: Use of the current standard and take completely wrong values > Use a prospective new standard for membrane structures and take right values Now we apply: enough curvature, enough pretension, enough supports = OK?

- Open as well as (partly) closed buildings/roofs have to be considered - Conical shapes: also consider a low point in the middle (not only an internal high point) - The basic shape of an air hall should be added

Future scope à Aero-elastic response à Deflections and movement of membranes à Problem wind tunnel testing: downscaling thickness, stiffness, and other characteristics CONCLUSION Collect data of the existing research on basic shapes (current publications)

à Qualitative information on non-standard shapes can be interesting to include (Ramon) à Information on inflatables (Jean-Christophe)

Specify model (location of measuring points, used sensors OK) and wind tunnel testing properties and characteristics (flow regime, post-processing) Update Round Robin exercise III proposal and start the project (basic shapes) First year: 2 or 3 basic models should be tested (as a start for more elaborated studies) Look for experts, experienced institutes… Contact different wind tunnels for testing (University Nantes (FR), von Karman Institute for Fluid Dynamics (BE), Wacker Ingenieure - Wind Engineering (DE), Wind Engineering Society – WES (UK), SL-Rasch, Barcelona, UGent, Florence (IT)…)

à Experience with testing and with post-processing FUNDING Is it possible to get funding for the study of the ‘membrane-specific’ aspects or for the wind-tunnel specific aspects? EU: pre-normative research? H2020? CORNET: collective research? http://www.cornet-era.net/ (19th Call for proposals with deadline 27 March 2015 National funding? Are wind-tunnel companies interested (mostly working for civil engineers)? Fire: Contribution from Vatyu Tanev for the SaP-‐report The document ‘140930_Brussels_WG5_FireContribution.pdf' is presented and discussed (http://www.novelstructuralskins.eu/wp-content/uploads/documents/Brussels2014/140930_Brussels_WG5_FireContribution.pdf) Check different applications of membranes with respect to fire behaviour

- Membrane contributes to the structural stability (check redundancy) - Membrane as shape defining element - Air supported membranes

Risk analysis

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à Is it allowed to use the membranes or not? Add more safety? Incombustible membranes?... à Could pieces of burning membrane fall down or could the entire structure collapse? à Is there enough time to leave the place? Thermal actions of the fire compartment Simple models à Advanced models Simple case studies à Temperature and burning speed > membrane melts > opening in membrane > thermal energy flows away > consider while designing the structure à Incombustible membranes: thermo conductivity of membrane (thermo energy stays inside) à Oxygen enters and allows all combustible material to burn, causing rise of the temperature è Temperature in the building! (open, enclosed…)

3. Existing research in context of the SaP report, and future Eurocodes See PowerPoint presentation 140929_Brussels_WG5_presentation.pdf (http://www.novelstructuralskins.eu/wp-content/uploads/documents/Brussels2014/140930_Brussels_WG5_presentation.pdf)

4. Following the SaP report: to advance on the key points Which kind of models, simulations are currently used à Educational Pack (documents, form finding, analysis) à Support professors in other Schools (cfr. COST Action on GLASS) Consider also flat membranes à Current application of second skins: double curvature is not a must (curvature-tension) SLS and ULS à Classify shapes and contingencies according to the Eurocode à Shapes in correlation to failure risk à Different ULS and SLS assessment? (cfr. Ponding-curvature)

5. Reliability analysis, calibration Jean-Christophe Thomas gives the presentation 140930_Brussels_WG5_Semi_proba_Approach.pdf. (http://www.novelstructuralskins.eu/wp-content/uploads/documents/Brussels2014/140930_Brussels_WG5_Semi_proba_Approach.pdf) Semi-probabilistic method à Compute reliability, based on ULS-SLS (Geometry, materials, actions, computing models) à 1 year ó 50 year (how temporary?) à Safety and failure domain (minimise failure domain) Compare the resistance of the structure and the effect of the actions à Remain in safety domain à Calculate the reliability index à 3 consequence classes linked to 3 reliability classes à Optimisation based on the different Limit States

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Summer School ‘FROM UNCERTAINTIES TO PARTIAL SAFETY FACTORS CALIBRATION: APPLICATION TO TENSILE MEMBRANE STRUCTURES’ is proposed for next summer. 1 Structural rules and safety for membrane structures 2 Risk analysis and Reliability computation (FORM, SORM…) 3 Uncertainties in design and reliability analysis (materials, loadings, reliability…) 4 Partial safety factors (general LS principle and calibration of safety factors)

6. Conclusions Intensify meetings and exchange à SaP report (with CEB/TC 250/WG5): an additional meeting end of November is proposed à Report on Existing Research to be established (Marijke Mollaert, Jimmy Colliers) à Start-up Round Robin exercise III (wind) to be launched (Marijke Mollaert, Jimmy Colliers) à Educational Pack (all) à A summer school on reliability of membrane structures: next summer (Jean-Christophe Thomas)

Attachments 140929_Brussels_WG5_presentation.pdf http://www.novelstructuralskins.eu/wp-content/uploads/documents/Brussels2014/140930_Brussels_WG5_presentation.pdf 140930_Brussels_WG5_FireContribution.pdf http://www.novelstructuralskins.eu/wp-content/uploads/documents/Brussels2014/140930_Brussels_WG5_FireContribution.pdf 140930_Brussels_WG5_Semi_proba_Approach.pdf http://www.novelstructuralskins.eu/wp-content/uploads/documents/Brussels2014/140930_Brussels_WG5_Semi_proba_Approach.pdf

COST Action TU1303WG5 meetingBrussels, 29‐30 September, 2014

Marijke Mollaert & Lars De Laet 1

COST Action TU1303

Novel Structural Skins

Improving sustainability and efficiency through

new structural textile materials and designs

www.novelstructuralskins.eu

WG 5 meeting

Brussels, 30 September, 2014

Marijke Mollaert, Jean‐Christophe Thomas

Novel structural skins:

Not frequently used? Not present in the city?

Can these structures withstand tornado’s, flooding, lightning?

Fire behavior?

Expensive?

Can tensile architecture contribute to a healthier city? A safer city?

WG5From material to structure and limit states: codes and standardisation

Memorandum of Understanding (MoU)

Exchange research results within WGs by means of published state‐of‐the‐art documents, research reports and seminars

Cooperate on common research objectives and further expand the cooperation Ensure complementarities in the performed studies Integrate the investigations, also from the industrial partners, in a multi‐disciplinary/multi‐

sector European context Increase the frequency of research visits, organise scientific seminars, Short Term Scientific

Missions Improve the research output and dissemination Bring research results relevant for industry to market

MoU

Exchange research results within WGs by means of published state‐of‐the‐art documents

In cooperation with CEN/TC 250/WG5 Membrane Structures

present Scientific and Policy Report (SaP‐Report)

state‐of‐the‐art overview / background document

design rules for membrane structures

To be published end 2014

Scientific and Policy Report (SaP‐Report)

The development of a common standardised approach

for the analysis of membrane structures

considering appropriate limit states and partial safety factors

compatible with the current Eurocodes

Basis of design EN 1990 – Eurocode 0 : « Eurocode of the Eurocodes »

basis of structural design

Actions EN 1991 ‐ Eurocode 1Actions on structures

EN 1997 ‐ Eurocode 7Geotechnical design

EN 1998 ‐ Eurocode 8Earthquake resistance

Materials

In progress

EN 1992 ‐ Eurocode 2Concrete

EN 1993 ‐Eurocode 3Steel

EN 1994 ‐Eurocode 4Composite steel concrete

EN 1995 ‐Eurocode 5Timber

EN 1996 ‐Eurocode 6Masonry

EN 1999 ‐Eurocode 9Aluminium

membrane structures

structural glass fibre‐reinforced polymer (FRP) composite materials

Transversalaspects

Robustess(project)

Existing structures(project)

Scientific and Policy Report (SaP‐Report)

Challenge: obtain a European harmonised view of the technical aspects



MoU

Ensure complementarities in the performed studies Integrate the investigations, also from the industrial partners Improve the research output and dissemination Bring research results relevant for industry to market

Contributions to the SaP report ‘Analysis and design of membrane structures: Results of a round robin exercise’

follow‐up Round Robin exercise II: Bi‐axial testing in preparation Round Robin exercise III: Wind in preparation Report on verifications

Do partial coefficients have to be applied on the actions or on the effects?

Is pre‐tension an action?in preparation

MoU

Short Term Scientific MissionsTo be stimulated

MoU

Task 1 Report on Existing Research: the state‐of‐the‐art = SaP report of CEN/TC 250/WG5Task 2 Report on Current Research: after 1,5; 2,5 and 3,5 years

Including summary reports of round robin exercises: input for standardisation Reports on case studies: input for the harmonisation of directives

Task 4 Completion of the state‐of‐the‐art guidance/educational pack: will be ready for dissemination at the final Research Conference + version available on the websiteTask 5 Report about Funding and deadlines for New Research will be presented to the Management Committee after the second and the third year+ at least one proposal for a new collaborative research projects idea will be submitted

Le Nuage, Montpellier, Philippe Starckwww.iaso.es; https://www.youtube.com/watch?v=LtnTCog1Sws

MoU

Publications: In the first part of the Action, state of the art reports for the most relevant sub‐topics will be established and communicated. At the end of the Action, the scientific outcomes will be published in the final report and the proceedings of the Research Conference and the recommendations for Standards as Technical Specifications. Journal Articles: It is a priority to join forces and produce at least one joint international peer reviewed scientific journal paper per year per working group. If allowed by the copyrights, also these articles will be made available on the website.Peter Gosling + team, Giogio Novati + team, Marijke Mollaert + team …Mention COST Action TU1303


1. SaP report: the last contributions: (1 h)2. Existing research in context of the SaP report, and future Eurocode: (3/4 h)3. SaP Report: to advance on the key‐points (1 h)4. Reliability analysis, calibration: (1/2 h)5. Conclusion: (1/2 h)

http://cita.karch.dk/Menu/Research+Projects/Behaving+Architectures


1. SaP report: the last contributions: (1 h)‐ contribution Alex Michalski for the SaP‐report (wind)

+ Proposal Round Robin exercise: collating wind tunnel data for the basic shapes of tensioned surface structures



Need for an accurate wind‐load standard for membrane structures

Overall pressure coefficients for ‘typical’ shapes

Local effects

Dynamic or aero‐elastic responses

Even simple doubly curved shapes

are not considered in the standards

Overview proposed by Alex Michalski

Wind tunnel tests: Round Robin exercise

H L

3,3 ‐1,5 ‐2,4 ‐1,5 ‐1,1 ‐1,0 ‐0,8 ‐0,6

‐1,7 ‐0,5 ‐0,3 ‐0,3 ‐0,6 ‐1,2 ‐1,0 ‐0,8

‐2,4 ‐0,3 ‐0,3 ‐0,2 ‐0,1 ‐0,1 ‐0,2 ‐0,5

‐1,6 ‐0,4 ‐0,2 ‐0,2 ‐0,1 ‐0,2 ‐0,2 ‐0,3

‐1,2 ‐1,0 ‐0,1 ‐0,1 ‐0,2 ‐0,1 ‐0,2 ‐0,3

‐1,0 ‐1,2 ‐0,1 ‐0,1 ‐0,2 ‐0,2 ‐0,2 ‐0,3

‐0,8 ‐1,0 ‐0,5 ‐0,1 ‐0,2 ‐0,2 ‐0,3 ‐0,3

‐0,6 ‐0,7 ‐0,7 ‐0,3 ‐0,3 ‐0,3 ‐0,3 5,1

L H

H L

6,3 0,0 ‐0,8 ‐0,3 ‐0,1 0,0 0,0 ‐0,3

‐0,1 0,1 0,2 0,3 0,3 0,0 0,2 0,3

‐0,7 0,1 0,3 0,2 0,1 0,3 0,3 0,2

‐0,3 0,1 0,2 0,2 0,4 0,3 0,3 0,2

‐0,1 0,1 0,3 0,4 0,2 0,3 0,2 0,2

0,1 0,2 0,3 0,1 0,3 0,3 0,3 0,2

0,1 0,2 0,2 0,3 0,3 0,3 0,1 0,0

‐0,2 0,3 0,1 0,1 0,2 0,2 0,0 6,8

L H

‐0,2 0,2 ‐1,1 0,0 ‐0,1 ‐1,2 0,0 ‐0,1

‐0,1 0,0 0,0 0,0 0,0 ‐0,1 0,0 0,0

‐0,1 0,0 ‐0,1 ‐0,1 0,0 0,1 0,0 ‐0,1

‐0,1 0,0 0,0 0,1 0,0 ‐0,1 0,0 ‐0,1

‐0,1 0,0 0,0 0,1 0,0 ‐0,1 0,0 ‐0,1

‐0,1 0,0 ‐0,1 ‐0,1 0,0 0,1 0,0 ‐0,1

‐0,1 0,0 0,0 0,0 0,0 ‐0,1 0,0 0,0

‐0,2 0,2 ‐1,1 0,0 ‐0,1 ‐1,2 0,0 ‐0,1

Full scale tests





1. SaP report: the last contributions: (1 h)‐ contribution Vatyu Tanev (fire)




1. SaP report: the last contributions: (1 h)‐ others contributions

report on verifications Do partial coefficients have to be applied on the actions or on the effects? Is pre‐tension an action?

in preparation inflated structures; is internal pressure an action?

http://www.form‐tl.de/





2. Existing research in context of the SaP report, and future Eurocode: (3/4 h)Participants present / give an overview of existing research to have contributions to the RER report, to be delivered according to the MoU, listing the main publications in complement to the SaP report‐ in terms of materials‐ in terms of loadings‐ in terms of numerical models‐ in term of reliability analysis dedicated to tensile structures

Mineapolis Metrodome





3. SaP Report: to advance on the key‐points (1 h)Which key points can we develop to advance on the SaP report at short term, medium term and longer term? What is feasible?‐ actions or effect on the actions?

‐ Contribution Bernd Stimpfle and the French Mirror Group‐ Contribution Nick Gibson: basic shapes

‐ pre‐stress: an action or not? ‐materials: identification of methods to derive the material parameters

‐ Round Robin exercise II‐ Input from CEN/TC 248/WG4

0

20

40

60

80

100

120

140

160

180

200

0 2 4 6 8

Stress (MPa)

Strain (%)

ContinuousCyclic1Cyclic2


3. SaP Report: to advance on the key‐points (1 h)‐ models: which models are currently used?

‐ for the material (isotropic, orthotropic, others?)‐ for the structure (analytic, numerical: linear analysis, finite element‐lagrangian

formulation, dynamic relaxation, minimization of potential energy, cable net models...)




3. SaP Report: to advance on the key‐points (1 h)‐ loading: identification of cp values for typical shapes of structures (Round Robin exercise II),

combination of wind and snow‐ limit state: overview of the typical structures in textile architecture (hypar, saddle, conical,

waveform, arched roofs... including inflatables) and describe the corresponding limit states, SLS and ULS, based on experience; specific limit states for inflatables?

‐ risks: definition of the risks in case of tensile membranes

Modern Tea House, Museum für angewandte Kunst, , Frankfurt, 2007, Kengo Kuma





4. Reliability analysis, calibration: (1/2 h)Overview of the global method Planning/organisation of summer school?





5. Conclusion: (1/2 h)Summary of actions, program for the next meeting


5. Conclusion: (1/2 h)AOB

UACEG, Sofia, Bulgaria -‐ Dr. Eng. Vatyu Tanev 1 / 7

Fire Engineering for Structural Membranes

1 General 1.1 Textile materials – reaction to fire Textile membrane materials as a building materials are classified by the European standard EN 13501-1 in different ranks. The same document also gives a classification of these products with regard to smoke development (s1, s2, s3) and the formation of flaming droplets/particles (d0, d1 and d2). Most of the PVC coated polyester materials of a common European producers are classified in class B1 (flame-retardant) and B2 (standard inflammability). The class B3 (easily inflammable) is not frequent in the production of textile membranes. The PTFE coated fiberglass are usually classified in class A2 (non-combustible as no flashover occurs). The tests for the classification are executed depending of the different ranks (A, B, C, D, E and F) conform to the next stated standards: Class A1: EN ISO 1182 and EN ISO 1716; Class A2: EN ISO 1182 or EN ISO 1716 and EN 13823 (SBI); Class B, C and D: EN 13823 (SBI) and EN ISO 11925-2; Class E: EN ISO 11925-2; Class F: Fire behaviour not determined. Class A1 is non-combustible and the requirement level and cannot be combined with any additional class. Class A2 is also classified as non-combustible as no flashover occurs for the application of the products in these classes. For classes A2 to D there are additional classes for smoke development s1, s2 or s3, and the amount of burning droplets emitted d0, d1 or d3 (e.g. A2-s1, d0). Class E only has additional class d2. Class F means that the product is not documented, the product does not meet the criteria for any class, or the manufacturer has not provided the fire properties for the product. Class F cannot be combined with any additional class either. EN ISO 1182: Reaction to fire tests for building products - Non-combustibility test;


EN ISO 1716: Reaction to fire tests for building products - Determination of the heat of

combustion; EN 13823: Reaction to fire tests for building products - Building products excluding floorings exposed to the thermal attack by a single burning item (SBI);

EN ISO 9239-1: Reaction to fire tests for floorings - Part 1: Determination of the burning behaviour using a radiation heat source; EN ISO 11925-2: Reaction to fire tests - Ignitability of building products subjected to direct

impingement of flames. Part 2: Single-flame source test

Additional classes for smoke development

Additional classes for burning droplets

s1 the structural element may emit a very limited amount of combustion gases

d0 burning droplets or particles must not be emitted from the structural element

s2 the structural element may emit a limited amount of combustion gases

d1 burning droplets or particles may be released in limited quantities

s3 no requirement for restricted production of combustion gases

d2 no requirement for restriction of burning droplets and particles

1.2 Textile materials – important data which are available but not presented

for the moment For PTFE coated fibreglass class A2 – all measured parameters from the different tests covered in the above mentioned standards; For PVC coated polyester B1 and B2 – all measured parameters from the different tests covered in the above mentioned standards.

2 Structural fire design procedure (EC 1 – with specific additions) 2.1 General

A structural fire design analysis should take into account the following steps as relevant:

– Selection of the relevant design fire scenarios; – Determination of the corresponding design fires; – Determination of the type of the structural system taking into account the role of the structural membrane:

- Structural membrane play a main role for the equilibrium (EQU) of the entire structural system – collapse of the membrane should lead to collapse of the supporting structure;

- Structural membrane do not influence the equilibrium (EQU) of the entire structural system.

– Calculation of temperature evolution within the structural members; – Calculation of the mechanical behaviour of the structure exposed to fire.


2.2 Design fire scenario (1) To identify the accidental design situation, the relevant design fire scenarios and the associated design fires should be determined on the basis of a fire risk assessment. (2) For structures where particular risks of fire arise as a consequence of other accidental actions, this risk should be considered when determining the overall safety concept. (3) Time- and load-dependent structural behaviour prior to the accidental situation needs not be considered, unless (2) applies. 2.3 Design fire (1) For each design fire scenario, a design fire, in a fire compartment, should be estimated according to EC1 Part 1-2, Section 3. (2) The design fire should be applied only to one fire compartment of the building at a time, unless otherwise specified in the design fire scenario. (3) For structures, where the national authorities specify structural fire resistance requirements, it may be assumed that the relevant design fire is given by the standard fire, unless specified otherwise.

3 Thermal actions for temperature analysis of fire compartment (EC1) 3.1 Standard temperature-time curve

( )1020 345.log 8. 1g tΘ = + + - Standard Fire Curve ( )0,32. 3,8.660. 1 0,687. 0,313. 20t t

g e e− −Θ = − − + - External Fire Curve ( )0,167. 2,5.1080. 1 0,325. 0,675. 20t t

g e e− −Θ = − − + - Hydrocarbon Fire Curve

Nominal Temperatute Time Curves

0

200

400

600

800

1000

1200

0 20 40 60 80 100 120 140

t, [time]

T, [C

o ]

Standard Fire CurveExternal Fire Curve

Hydrocarbon Curve


3.2 Natural fire models 3.2.1 Simplified fire models (1) Simple fire models are based on specific physical parameters with a limited field of application. (2) A uniform temperature distribution as a function of time is assumed for compartment fires. A non-uniform temperature distribution as a function of time is assumed in case of localised fires. 3.2.1.1 Compartment fires (1) Gas temperatures should be determined on the basis of physical parameters considering at least the fire load density and the ventilation conditions. 3.2.1.2 Localised fires

(1) Where flash-over is unlikely to occur, thermal actions of a localised fire should be taken into account. 3.2.2 Advanced fire models

(1) Advanced fire models should take into account the following: – gas properties, – mass exchange,

– energy exchange. (2) One of the following models should be used: – One-zone models assuming a uniform, time dependent temperature distribution in the

compartment. – Two-zone models assuming an upper layer with time dependent thickness and with time dependent uniform temperature, as well as a lower layer with a time dependent uniform

and lower temperature. – Computational Fluid Dynamic (CFD) models giving the temperature evolution in the compartment in a completely time dependent and space dependent manner.


4 Simple case study (proposals for approach) If we observe a very simple building (Fig 1 and Fig 2), one span portal frame multiplied in the longitudinal direction several times covered with not pre-stressed or slightly pre-stressed structural membrane from:

Case I-a - PVC coated polyester fabric with a fire class B1, ETFE cushions, or other material which is classified as B1 or B2;

Case I-b – PTFE coated fiberglass with a fire class A2 or other material which is classified as A1 or A2.

Fig 1. Steel, aluminum or timber structure

Fig 2. Steel, aluminum or timber structure partly closed with structural membrane


If the building is covered with a PVC coated polyester Case ”I-a” and fire starts inside or close to the building outside the PVC fabric will melt if the heat flux (convection + radiation) from fire is strong enough. The membrane is fire-retardant and do not burn itself if the source of fire is not present. This process will lead to open a gap in the membrane surface which will prevent the structural components of overheating. In such a case the approach should be:

- From testing data we should know the melting temperature of the material and also we should know how fast the material is melting and burning;

- For determining the temperature of the structural elements we should use Natural fire models, Compartment fire – parametric temperature-time curves or Advanced fire models.

Fig 3. Growing of fire, melting a part of the membrane surface

Fig 4. Growing of fire, melting a bigger part of the membrane surface


If the building is covered with a PTFE coated fiberglass Case ”I-b” and fire starts the membrane will not melt or start to burn. In this case no changing of the ventilation conditions would be presented. In such a case the approach should be:

- From testing data we should know a lot of physical parameters for the textile materials like: density of boundary of enclosure, specific heat of boundary of enclosure, thermal conductivity of boundary of enclosure, opening factor of the fire compartment;

- For determining the temperature of the structural elements we should use Natural fire models, Compartment fire – parametric temperature-time curves or Advanced fire models.

To be continued

General scheme for the verification of strength

structural elements in the semi-probabilistic method

1JC Thomas 30/09/2014 COST Action TU1303 WG5

Eurocode 0: annexe C: Basis for Partial Factor Design and Reliability Analysis

The different methods


View of the probability density and the failure domain

and the safety domain


Eurocode 0: annexe C: Basis for Partial Factor Design and

Reliability Analysis


Design point and reliability index

according to the first order reliability method (FORM)

for Normally distributed

uncorrelated variablesEurocode 0

β : Reliability index

P: design

point

Frontier of the

failure domain

From: Calibration des codes de

conception et de calcul des

constructions :

approches fiabilistes, Jean

Armand CALGARO


Probability and limit states

Serviceability limit states

SLS

From: Calibration des codes de conception et de calcul des constructions :

approches fiabilistes, Jean Armand CALGARO

Ultimate limit states

Probability of failure – period of 50 years - ELU


Eurocode 0: Annex B (informative) Management of StructuralReliability for Construction Works

The 3 reliability classes are associated with the 3 consequences classes


Eurocode 0: annexe C: Basis for Partial Factor Design and Reliability Analysis


Calibration: general principles

the procedure is divided into six stages;

1 - choose the class structure, define:

- the mechanical elements

- the failure modes

- the design variables

- their probabilistic properties

2 - select a number of design situations and assess their weight

3 - set a target reliability index

4 - size each design situation by adjusting a variable

5 - choose a penalty function M and look delta minimizing the function:

6 - then calculate the new partial factors

Illustration with 2 limit states


Training school, or summer school

Draft of programm

FROM UNCERTAINTIES TO PARTIAL SAFETY FACTORS CALIBRATION : APPLICATION TO TENSILE MEMBRANE STRUCTURES

1 Key design structural rules for service and safety

1.1 Tensile structures

1.2 Inflatable structures

2 Basis of risk analysis and reliability analysis

SAP Report

2014

2 Basis of risk analysis and reliability analysis

2.1 Risk analysis

2.2 Relability computation (FORM, SORM, other..)

3 Involved uncertainties in design and reliability analysis

3.1 Materials

3.2 Loadings

3.3 Models

3.4 Reliability of tensile membranes and inflatable structures

4 Partial safety factors calibration

4.1 General principle of limit states

4.2 Calibration of partial safety factors


Eurocode

202?

novel structural skins€¦ · temperature and burning speed > membrane melts > opening in...

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