Transcript Specification of a round robin exercise for the design of membrane

TENSINet Symposium
Sofia, 15th –17th September 2010
Specification of a round robin exercise for the
design of membrane structures
Prof. Peter Gosling, Dr. Ben Bridgens
Newcastle University, UK
TENSINet Symposium
Sofia, 15th –17th September 2010
What is a Round Robin exercise?
“In experimental methodology, a round robin test is a test (measurement,
analysis, or experiment) performed independently several times.
This can involve multiple independent scientists performing the test with the use
of the same method in different equipment, or a variety of methods and
equipment.
In reality it is often a combination of the two, for example if a sample is
analysed, or one (or more) of its properties is measured by different laboratories
using different methods, or even just by different units of equipment of identical
construction.”
TENSINet Symposium
Sofia, 15th –17th September 2010
Why undertake a Round Robin exercise?
“…
There are different reasons for performing a round robin test: e.g. verification of
a new method of analysis: If a new method of analysis has been developed, a
round robin test involving proven methods would verify whether the new
method produces results that agree with the established method.”
TENSINet Symposium
Sofia, 15th –17th September 2010
Drivers in the analysis of Membrane Structures
TENSINet Symposium
Sofia, 15th –17th September 2010
TENSINet Symposium
Sofia, 15th –17th September 2010
Relevant information
Material Test
Experience
Mathematical representation
Of uncertain quantities
Histogram
Data-fitting test
Density or distribution
function
Statistics or parameters
estimation
Define performance criteria
Finite Element Analysis
(e.g.)
FORM
Risk evaluation
Consequence
Design decision
TENSINet Symposium
Sofia, 15th –17th September 2010
Load type
Minimum
strength
(kN/m)
safety
factor
Safety
index ()
Unfactored
combination
Wind
Snow
Factored
combination
Wind
Snow
12.4
11.3
14.8
14.1
6.2
6.8
5.2
5.5
3.8
3.8
3.8
3.8
TENSINet Symposium
Sofia, 15th –17th September 2010
CEN TC250 WG5
CEN TC248 WG4
EUROCODE 10
TENSINet Symposium
Sofia, 15th –17th September 2010
TENSINet Symposium
Sofia, 15th –17th September 2010
TENSINet Symposium
Sofia, 15th –17th September 2010
Benefits of a Round Robin exercise?
1. The methods used in the round robin exercise may be readily
incorporated into the EN as indicative analysis approaches in their own
right.
2. By analysing the same membrane structures it will be possible to see
how the analysis is applied to each structure case, and to be able to
understand what may be expected as outputs from the analysis. This
will also prove useful in helping to define the “reporting section” of the
EN.
3. Data from the round robin exercise will be used to identify the
material test requirements as inputs to the particular analysis
approach. This will contribute to the drafting of the EN being produced
by CEN248 Working Group 4 (Coated Fabrics).
4. Assist in defining the direction and activities of the TENSINet Analysis
& Materials Working Group.
TENSINet Symposium
Sofia, 15th –17th September 2010
Principles of the exercise
 A number of “real” membrane structure projects have been
proposed by contractors and consultants from across Europe
specialising in the design and construction of membrane
structures.
 A relatively small number of projects have been selected as part of
the round robin exercise.
 They have been chosen to enable a range of membrane structures
to be analysed combining typical support and boundary conditions.
TENSINet Symposium
Sofia, 15th –17th September 2010
Principles of the exercise
 Information is provided in sufficient detail for each membrane
structure project so as to avoid particular types of ambiguity in the
resulting design.
 Certain specific information and data relating to material stiffness
properties, for example, is omitted and required to be provided by
the participating organisation.
The choice of data and information to provide or to leave unspecified
within the round robin exercise should prove useful in providing further
insights to the TENSINet Analysis & Materials Working Group concerning
material stiffness data assumptions, testing needs & procedures,
including timing and specification, for example. Specifying all details of
the membrane structure projects would potentially limit the value of the
exercise.
TENSINet Symposium
Sofia, 15th –17th September 2010
Specification of the exercise
– information supplied
1.
Structure geometry – e.g. positions of support points, etc.,
2.
Structure support definitions – e.g. masts, cables, belts, etc., as applicable,
3.
Boundary conditions – e.g. simple/moment supports, fixed/sliding supports,
rotational freedoms/constraints, etc.,
4.
Membrane material type & grade – e.g. PVC/polyester, PTFE/glass, Si/glass,
PTFE/PTFE, etc., types II-V,
5.
Supporting structure material types – e.g. steel, aluminium, timber, wire
ropes, etc.,
6.
Fabric orientation/patterning – warp and fill directions.
7.
Fabric prestress – warp and fill.
8.
Areas of fabric reinforcement (as applicable)
9.
Wind load – in the form of pressures (kN.m-2),
10.
Snow load – projected plan area (kN.m-2),
11.
Other considerations – e.g. exo-thermal behaviour (expansion, creep, etc.),.
TENSINet Symposium
Sofia, 15th –17th September 2010
Specification of the exercise
– information not supplied
1.
Membrane structure material stiffness data where this is not
(normally) supplied as part of the specific task,
2.
Supporting structure material data,
3.
Seam stiffnesses
4.
Stiffnesses of reinforced areas (e.g. 2 or more layers of fabric in
high load areas)
5.
Membrane material elasticity model.
Specification of the exercise
– analysis assumptions
The analysis of the membrane structure will be under the assumption of quasi
static loads (e.g. peak values). Other aspects of the analysis methodology are
not prescribed. They may be chosen freely, and are expected to be that which
are normally used in practice by the participating organisation.
TENSINet Symposium
Sofia, 15th –17th September 2010
Task completion and reporting
The round robin exercise is proposed as a non-commercial activity. It is
intended to serve the purpose of advancing the scientific and engineering
practice in the analysis and design of membrane structures. Participation in
the round robin exercise is further based on the following principles:
1. Involvement in the round robin exercise is voluntary.
2. Completion of the round robin tasks are undertaken without fee and liability.
3. The completed tasks will not be used outside the remit of the round robin
exercise and will not be made available in a format that could be used for design
purposes by a third party.
4. The membrane structure task results will be made anonymous.
5. Reporting of results from the round robin tasks will be made using a standard
form (provided) via a dedicated Analysis and Materials Working Group page on
the TENSINet website.
TENSINet Symposium
Sofia, 15th –17th September 2010
Task completion and reporting
– assumptions, information, & outcomes
to be reported
1. Details of the analysis methodology,
2. Statement of design criteria used to select the membrane material,
3. Membrane structure material stiffness data (tension & shear) used in the analysis,
stating whether specific (e.g. test, database, etc.) or assumed,
4. Seam stiffness data (if) used in the analysis (e.g. test, database, etc.) or assumed
5. Stiffness data of reinforced areas (e.g. 2 or more layers of fabric in high load
areas); (e.g. test, database, etc.) or assumed,
6. Supporting structure material data used in the analysis, stating whether specific
(e.g. test, database, etc.) or assumed,
7. Membrane material elasticity model,
8. Assumptions made to obviate the need for specific data not provided as part of the
task specification,
9. Reasons for not making use of any part of the information provided as part of the
task specification,
TENSINet Symposium
Sofia, 15th –17th September 2010
Task completion and reporting
– assumptions, information, & outcomes
to be reported
10. Magnitude and position of maximum warp stress,
11. Magnitude and position of maximum fill stress,
12. Magnitude and position of minimum warp stress,
13. Magnitude and position of minimum fill stress,
14. Magnitude and position of maximum shear stress.
15. Magnitude and position of maximum vertical membrane displacement,
16. Magnitudes and directions of all support reactions.
17. Details of design fabric.
TENSINet Symposium
Sofia, 15th –17th September 2010
Membrane structure tasks – example candidate structures
TENSINet Symposium
Sofia, 15th –17th September 2010
Membrane structure tasks – example candidate structures
TENSINet Symposium
Sofia, 15th –17th September 2010
Membrane structure tasks – example candidate structures
TENSINet Symposium
Sofia, 15th –17th September 2010
TENSINet Symposium
Sofia, 15th –17th September 2010
The driver behind the inception of the Group is the linking
together of testing and analysis such that each are supportive
and inform each other, rather than being considered
independently as is generally the current practice.
TENSINet Symposium
Sofia, 15th –17th September 2010
TENSINet Symposium
Sofia, 15th –17th September 2010
TENSINet Symposium
Sofia, 15th –17th September 2010