assessment/design of “special risk” plants subjected to seismic
TRANSCRIPT
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Assessment/design of “special risk” plants subjected to seismic loading:
needs for code improvement.
Oreste S. Bursi Department of Civil, Environment and Mechanical Engineering,
University of Trento, Via Mesiano 77, 38123, Trento, Italy.
September 5, 2013
Contact Oreste S. Bursi, Ph.D., P.E., MASME, MASCE Professor of Structural Dynamics and Control e-mail: [email protected]
Table of Contents
1. Damages and consequences in “Special Risk” Plants
2. Situation in Europe/USA
3. Needs for Code Improvement
4. Some examples for piping networks/components
5. Common Protocol for Qualification of Research Infrastructures
Acknowledgments Prof. Helmut Wenzel
September 5, 2013 Page 2
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“Special risk” plants
September 5, 2013
Refinery Conflagration Kocaeli Earthquake
Turkey, 1999 Pipeline failure
Kobe Earthquake Japan, 1995
Refinery Conflagration Tohoku Earthquake
Japan, 2011
Consequences: - loss of life; - loss of asset; - environmental pollution...
Piping Systems and Components suffered severe damages under earthquakes.
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“Special risk” Plants
September 5, 2013
Examples of real events with casualties in neighbourhoods
*French environmental codes (articles R. 563-1 to R.563-8) divide structures into two categories namely, “normal risk (1)” and “special risk (2)” structures, referring to a specific earthquake-resistant regulation depending on one or other of these categories; (1) refers to structures for which consequences of an earthquake remain limited on
their personnel, on environment and nearby facilities; (2) refers to structures for which consequences can exceed the immediate vicinity of
these structures.
Event Dead Injured
Ammonium nitrate explosion
(France, 2001) 30 2242
Refinery disaster (USA, 2005)
15 170
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Requirements in Europe
September 5, 2013
European Union Law: DIRECTIVE 2012/18/EU (amendments of 96/82/EC) on the control of major-accident hazards involving dangerous substances Annex II: Minimum data and information to be considered in the safety report referred to in Article 10 4. Identification and accidental risks analysis and prevention methods: (a) detailed description of the possible major-accident scenarios and their probability or the conditions under which they occur including a summary of the events which may play a role in triggering each of these scenarios, the causes being internal or external to the installation; including in particular:
(i) operational causes; (ii) external causes, such as those related to domino effects, sites that fall outside the scope of this Directive, areas and developments that could be the source of, or increase the risk or consequences of a major accident; (iii) natural causes, for example earthquakes or floods;
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Actions in USA/EUROPE
The Seismic Task Committee of ASCE Energy Division issued specific Guidelines for Seismic Evaluation and Design of Petrochemical Facilities (1997, 2011), in order to provide practical guidance to engineers involved in seismic design and evaluation. Though these Guidelines are largely based on qualitative seismic risk concepts and deterministic approaches, no corresponding European technical document exists in this respect. In addition, also the requests to CEN/TC 250 for Eurocode amendments do not include specific issues for process plants (CEN/TC 250, 2013) - ASCE Task Committee on Seismic Evaluation and Design, Guidelines for Seismic Evaluation and Design of Petrochemical Facilities, 1997 1st Edition; 2011, 2nd Edition. - CEN/TC 250, Response to Mandate M515 EN, N_982 Report, May, 2013.
Seismic hazard
Geological structure data Historic earthquake data
Active fault data
Analysis on earthquakeincidence / seimic ground
motion propagation
Seismic hazard curve
Response spectrum
Fragility evaluation of support structures /
components
Seismic response evaluation
Structural strengthevaluation
Accident sequenceevaluation
Scenario analysis
System reliability evaluation
Fragility curves Accident SequenceOccurrence Frequency
PERFORMANCE OBJECTIVES AND SEISMIC DESIGN CATEGORIES
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Action in Europe
PREVIOUS RELATED RESEARCH PROJECTS - Structural safety of industrial steel tanks, pressure vessels and piping
systems under seismic loading (INDUSE) - Development of INnovative DEvices for Seismic Protection of
PeTrocHemical Facilities (INDEPTH) - Integrated European industrial risk reduction system (IRIS) - Seismic-lnitiated events risk mitigation in LEad-cooled Reactors (SILER) - Enhancing resilience of communities and territories facing natural and na-
tech hazards (ENSURE) The aforementioned projects and especially those devoted to “special risk” petrochemical plants neither proposed a rigorous seismic probabilistic risk-based assessment/design methodology for structures/plant components with associated probabilities of failure – or simplified PBEE procedures including investments/losses - nor defined proper seismic hazard analyses – or realistic importance factor γI values foreseen in Eurocode 8, Part 1 -.
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This type of analysis considers some risk factors: I. Personnel;
II. Environment;
III. Nearby facilities
• Increasing the effective design acceleration level, which is equivalent to increasing the return period of the seismic load
• Introducing safety measures like: structural strengthening, shut down measures or physical distance to nearby facilities or settlements
Needs for Code Improvements Quantitative Risk Analysis
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Action in Europe – France
September 5, 2013
Recent National Regulations of FRANCE demand seismic safety evaluations of existing industrial installations to be completed by 2015. - Regulation: DEVP1102251A (Réglementation en vigueur - Installations Classées)
PGA level (m/s2)
Seismic Zone New Installations Existing Installations
1 0.88 0.74
2 1.54 1.3
3 2.42 2.04
4 3.52 2.96
5 6.60 5.55
They corresponds to a Return Period of 5000
years
They corresponds to a Return Period of 3000
years
Very high levels of PGA lead to over-conservative designs
Na-Tech disaster risk management in France INERIS: Institut National de l’Environment Industriel et des Risques
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Actions in other European countries
September 5, 2013
Country Importance Factor, I
(for special risk structures)
National Return Period
TR (Years)
Return Period calculated using Eurocode 8 based on I
TL (Years)
France 2.2 5000 5057
Germany 1.65 - 2133
Italy 2 1950 3800
Norway 1.8 2000 2770
I = (TLR/TL)-1/k
TLR = Reference return period, 475 years (10% Prob. of Ex. in 50 years) TL = Return period k = corrective factor taken as 3
Onshore structures inside the scope of EN1998. Target reliability that depends on consequences of failure. In operational terms one multiply the reference seismic action by the importance factor γI
Inconsistent Return Period values
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Other needs for Code Improvement
September 5, 2013
In order to evaluate the safety of structures, Eurocode 0 allows for a probabilistic analysis to be performed in the following ways:
METHOD #1
Reliability estimation by means of β index.
Gaussian distribution
General distribution
METHOD #2 Probability of failure estimation
Integration of pdfs Direct calculation
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Other needs for Code Improvement
September 5, 2013
Eurocode 0 defines a probability of failure based on the acceptable risk in terms of human casualties.
Only the case of standard events on single structures is considered; the case of correlated events in special risk structures is omitted.
In the case of “special risk” plants reference probabilities of failure are missing.
One could refer ASCE/SEI Standard 43-05 for Application to Nuclear Power Plants.
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American European
- ASME B31.3 (2006) - ASME B31.1 (2001) - ASME SecIII Div1 (2002) - FEMA 450 (2003)
- EN 1998-4 (2006) - EN 13480-3 (2002)
Inadequacy of Seismic Design Standards for Piping Networks and Components
Several seismic design Codes and Standards exist for piping systems
- Current design Standards have been found over-conservative (Touboul et al., 2006; Otani et al., 2011).
- Modifications have been proposed to relax this conservatism.
- Some components, e.g., Bolted Flange Joints, Tee Joints do not have seismic design rules.
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Needs for Code Improvements Limit States vs. Allowable Design approaches
September 5, 2013
- A lack of proper seismic design codes for piping system components, e.g., Tanks, piping systems and flanges, exists.
- These components are designed with allowable design approach.
- Eurocode is based on limit state design; a need exists for performance-based design developments.
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Experimental tests on BFJs Instrumentation and measurements
Rotation: φtot φtot = φf + φp φp = φ1 + φ2 φf = I1 + I2
Flange displacement: δtot
δtot = (δ1 + δ2)/2
Measured by E, F, G and H
Fig. (a) Placements of strain gauges; (b) instrumentations in a bending specimen; (a) instrumentations in an axial specimen.
8 strain gauges in all specimens. Axial tests: - 8 displacement transducers. Bending tests: - 12 displacement transducers; - two inclinometers.
September 5, 2013 Page 16
Performance of non-standard BFJs Comparison with Design Standards
Bending
Test
Mleak
(kNm)
Mmax
(kNm)
My+
(kNm)
My-
(kNm)
Mleak / Ma,D
My / Ma,D
BSML18 99 196 125 - 1.73 2.19
BSML27 106 203 151 - 1.86 2.65
BSCL18 80 190 121 112 1.40 2.12
BSCL27 91 201 132 134 1.59 2.31
Standard Allowable moment
Ma,D (kNm)
Yield moment
My,D (kNm)
Ultimate moment
Mu,D (kNm)
Allowable force
Fa,D (kN)
EN 13480-3 51.23 114.60 159.23 885.20
ASME B31.1 & B31.3 57.08 127.31 176.78 885.20
CSA-Z662-07 - - 132.39 -
Allowable, yield and ultimate design loads by Standards
Experimental moments
Standard Allowable moment
Ma,D (kNm)
Yield moment
My,D (kNm)
Ultimate moment
Mu,D (kNm)
Allowable force
Fa,D (kN)
EN 13480-3 51.23 114.60 159.23 885.20
ASME B31.1 & B31.3 57.08 127.31 176.78 885.20
CSA-Z662-07 - - 132.39 -
Reza, M.S., BURSI, O.S., Paolacci, F, “Performance of
Seismically Enhanced Bolted Flange Joints for
Industrial Piping Systems”, International Journal of
Pressure Vessels and Piping, 2013, submitted.
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Examples of limitations of Eurocode 8 q factor issue in a Case Study
September 5, 2013
• Analyses were carried out with q = 4 and PGA = 0.35g (Paolacci et al. 2013 )
• A non-linear time history analysis entailed a q = 2 indicating a deficiency of Eurocode 8 .
• Eurocode suggests values of q factor assuming rigid floor movements.
• In fact, piping systems on support structures do not respond as rigid floors.
Main vibration mode
with pipes
Main vibration mode
w/o pipes
Case Study on a piping
system
Paolacci F, Reza MS, Bursi OS, (2013). Evaluation and Design of Refinery Piping Systems in Earthquake-prone Areas. Journal of Pressure Vessel Technology, ASME, (under review)
September 5, 2013 Page 18
Damping estimation on piping networks
An Elbow Tee-joint Bolted flange joint
Support #1 Support #2 1000 kg mass
Material Type PS92 Rules France
RG 1.61 Oper. Basis Earth. USNRC
RG 1.61 Safe ShutD. Earth. USNRC
Japanese Nuclear Stations
Welded steel 2 2 4 1
Bolt steel 4 4 7 2
Pipelines (φ>305 mm) 2 3 0.5
Pipelines (φ<305 mm) 1 2 0.5
Reza, M.S., Abbiati, G., BURSI, O.S.,
Paolacci, F. “Seismic Performance
Evaluation of a Full-Scale Industrial Piping
System at Serviceability and Ultimate Limit
States”, International Journal of Pressure
Vessels and Piping, 2013, submitted.
September 5, 2013 Page 19
Identification Tests (IdTs)
Identification tests IDT 1 Without water
IDT 2 With water and low pressure (0.1
MPa) IDT 3 With water and pressure (3.2 MPa)
IDT4 Long signal with water and low
pressure (0.1 MPa)
Fig. Accelerometer positions
Fig. Accelerometer
A4x
Mode
Frequency, Hz Damping
IDT1 IDT2 IDT3 IDT1 IDT2 IDT3
1 4.00 3.41 3.46 0.0048 0.0059 0.003
2 7.01 5.55 5.54 0.0032 0.012 0.0016
3 7.98 7.17 7.23 0.0151 0.0018 0.002
4 8.74 8.94 7.54 0.0033 0.0193 0.006
5 9.28 10.14 9.15 0.0124 0.012 0.0234
6 11,85 12.47 10.17 0.0022 0.0149 0.0125
7 12,21 14.38 12.58 0.002 0.0058 0.0051
8 14,15 16.68 14.46 0.0056 0.0024 0.0042
9 - 17.32 16.72 - 0.0145 0.001
10 - 18.19 - 0.0183
- Modes of the PS were confirmed.
- Addition of water stiffened the structure.
- No considerable effect of pressure on the stiffness
- A 0.5% damping of the PS was confirmed.
Results of Identification tests
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Other Needs for Code Improvement Consideration of multiple hazards outside and inside plants
September 5, 2013
Different type of hazards have to be considered after a seismic event, in particular the earthquake can induce others dangerous events like explosion, tsunami, etc.
Tohoku, 11th March 2011 Earthquake, tsunami and explosion
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Needs for Code Improvements Consideration of multiple hazards
September 5, 2013
To evaluate this type of problems both correlation between the events and rare events probability have to be considered. We need to consider multiple hazards within a plant too.
CORRELATION
BETWEEN EVENTS
Earthquake
Tsunami
Explosion
Etc.
Furthermore, to evaluate the probabilities of this events, that are very small, it is important to set appropriate numerical algorithms to investigate rare events.
1. Evaluation of the suitability of the General Management Requirements of EN ISO/IEC 17025 for RTD infrastructures; 2. Evaluation of the suitability of the General Technical Requirements of EN ISO/IEC 17025 for RTD infrastructures; 3. Identification of Specific Technical Requirements for the RTD seismic testing by - On-site Testing - Shaking Table - Reaction Wall; 4. Identification of Specific Technical Requirements relevant to documentation and data management taking into account the requirements of NA1 for a Common European Data Base; 5. Issue of a Draft Common Protocol for the qualification with respect to the General Management and Technical Requirements; 6. Drafting of Specific Technical Requirements for RTD testing; 7. Drafting of Specific Technical Requirements for data management; 8. Implementation on a voluntary basis of the draft Common Protocol in some laboratories; 9. Development of the Final Common Protocol for the Qualification.
Protocol for the Qualification of Research Infrastructures – Outcome of the WP3/NA2 SERIES Project
September 5, 2013 Page 22
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Oreste S. Bursi, Ph.D., P.E., MASME, MASCE Professor of Structural Dynamics and Control e-mail: [email protected]
Thank you for your attention! Questions?