atlas thermosiphon project piping design and seismic analysis framework délio ramos en/mme,...
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ATLAS thermosiphon project
Piping design and seismic analysis framework
Délio Ramos EN/MME, 28.05.2010
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Outline
• Piping layout• Regulations and standards• Strength analysis to EN 13480• Seismic analysis– Calculation method– Assumptions and requirements– Seismic actions– Load combination
• Conclusion
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LayoutDesign goal:
A. Define supports layout in order to allow enough flexibility for thermal loads
B. Provide sufficient piping restraints to limit static deflection and dynamic (seismic) load consequences
From A. Bitadze
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Regulations and standardsGeneral Safety Instruction
GSI-M2 - Standard Pressure Equipment
European Directive 97/23/EC
CERN
Euro
pean
regu
latio
ns
Eurocode 8EN 1998-1 GeneralEN 1998-4 Silos, tanks and pipelines
EN 13480 – Metallic industrial piping
ATLAS Seismic requirements
Actions (from national regulations)
Piping Design
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EN 13480 Strength analysis
Permanent mechanical loads
Occasional or exceptional loads
Thermal and variable loads
MA + MB obtained directly from the FE model. k=1.2 for seismic loads.
Applied moments and their combination
From Ansys 3D model Excel or Ansys post-processor
k=1
Criteria Allowable stresses
N<7000 cycles => U=1
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Preliminary designD. Ramos, Piping analysis for the ATLAS thermosiphon project - Preliminary engineering analysis, EDMS 1064571, 2010-04-03
020406080
100120140160180
0 20 40 60 80 100 120 140 160 180 200
Str
ess
(MP
a)
Element number
S1 (MPa) fh
020406080
100120140160180
0 20 40 60 80 100 120 140 160 180 200
Str
ess
(MP
a)
Element numberS1 (MPa) fh
Pipe DN25 Pipe DN50
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Earthquake: Methods of analysis
• Options provided by EN 1998-1 for the design of buildings:– Linear static analysis (“lateral force” method or
“equivalent static”)– Modal response spectrum analysis– Non-linear static– Non-linear dynamic (time-history)
Implemented in Ansys but requires post-processing to combine loads from X, Y and Z action spectrum
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Response spectrum analysis
Mode combination
Structure response
Eigenmode-eigenvalue analysisSpecified response spectrum
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Combination of modal responses
• Sum of squares of modal responses (SRSS)– When all relevant modal responses may be
regarded as independent of each other (Tj<=0.9Ti)• Complete quadratic combination (CQC)– If Tj<=0.9Ti not satisfied
Both available in Ansys
Clause 4.3.3.3.2, EN 1998-1
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Modelling requirementsClause 5.4.1, EN 1998-4
ok
okok
!!
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Seismic actions specificationBenincasa and Schmidt, 2000
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Combination of X, Y, Z action’s effects
• SRSS combination– Is the reference method (conservative)– Yields the expected result if the modal
contributions have been combined using the CQC rule
• 30% rule as an alternative
Clause 4.3.3.5.1, EN 1998-1
Easier implementation in Ansys
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Conclusion
• Strength analysis of the piping to EN 13480 has been performed on a preliminary design and will be repeated once the layout has been completely approved.
• The requested seismic analysis can be performed following the procedures of Eurocode 8– Through a response spectrum analysis (linear)– CQC modal contribution combination + SRSS action combination– For specified X, Y and Z spectra applied to all supports
• The seismic analysis will not take into account the– Effects of the supporting structure dynamics– Influence in the actions from the difference in elevation