Seismic Safety, Risk Reduction and Performance-Based Design Aimed at Nuclear Facility Structures

1. Seismic Safety, Risk Reduction and Performance-Based DesignAimed at Nuclear Facility Structures Bozidar Stojadinovic, Associate Professor Department of Civil and Environmental Engineering University of California, Berkeley

2. Outline • What is performance-based design? • How to design structures to reduce risk? • What are the safety-increasing innovations in structural engineering? • Why should we do this for the new nuclear cycle in the US?

3. Performance-Based Design • Design to achieve specified results rather than to adhere to particular technologies or prescribed means (Moehle, EERI Distinguished Lecture, 2005) • Directly address the needs of the owner or user of the system or structure in their risk environment

4. A code provision (ASCE 43-05: 6.2.2(a)): “Minimum joint reinforcement shall consist of X-pairs of #4 diagonal cross-ties spaced 12 in. on center.” Prescription vs. Performance

5. Prescription vs. Performance • What is the performance? • Is such joint safe? • If so, what is the level of safety? • If so, how much does it cost to be so safe? • Would #3 cross-ties spaced 6 in. on center be better or worse? Safer? Less expensive? Easier to build?

6. Performance-Based Design:Earthquake Engineering View Prof. Mahin, CEE 227 Lectures

7. Performance-Based Design:Deterministic Quantification Prof. Mahin, CEE 227 Lectures

8. Performance-Based Design:Probabilistic Quantification Prof. Mahin, CEE 227 Lectures

9. How to Design for Performance? Prof. Mahin, CEE 227 Lectures

10. Probabilistic Framework

11. Performance-based Evaluation Example :How Safe are our Bridges? Type 11 Type 1

12. Intensity Measure (IM) Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Decision Variable (DV) Framework for Bridge Evaluation Hazard Model Select and scale ground motions Demand Model Damage Model Decision Model

13. Intensity Measure (IM) Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Decision Variable (DV) C L Framework for Bridge Evaluation Do non-linear time-history analyses Hazard Model Demand Model Damage Model Decision Model

14. Intensity Measure (IM) Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Decision Variable (DV) Framework for Bridge Evaluation Performance (damage) states Hazard Model Demand Model Damage Model Decision Model

15. Intensity Measure (IM) Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Engineering Demand Parameter (EDP) discrete Damage Measure (DM) continuous Decision Variable (DV) Framework for Bridge Evaluation Deaths? Dollars? Down-time? Hazard Model Demand Model Damage Model Decision Model

16. Framework for Bridge Evaluation Outcome: Repair cost ratio fragility curves Demand Model Sa(T1)=1g

17. Common Probabilistic Basis for Civil and Nuclear Structures • Given a seismic hazard environment and a structure, the probability that a performance objective is achieved is: • Consider probability distributions of seismic hazard, of demand and of capacity due to: • Lack of knowledge (epistemic uncertainty) • Record-to-record ground motion randomness (aleatory uncertainty)

18. Seismic Hazard and Probability of Failure • Hazard: probability of exceeding a value of ground motion intensity (hazard curve) • Failure: a comparison demand and capacity

19. Probability of failure is smaller than probability of hazard Risk reduction ratio at the structure level DOE-1020 and ASCE 43-05:(Nuclear) Acceptance Criteria

20. Conventional Design:Acceptance Criteria • Probability of failure is, implicitly, assumed equal to the probability of hazard • Design equation: • Capacity reduction • Demand amplification at the structural element level

21. CommonRisk-Informed Design Framework Hazard vs. Failure Conventional Structures Nuclear Facility Structures Design Equation

22. Common Risk-Informed Design Framework • New nuclear power plants can be designed using a risk-informed performance-based framework • Models for most elements of the structure exist, including aleatory and epistemic uncertainties • Modeling can be extended to: • Other extreme hazards (natural and man-made) • Ageing effects (construction and maintenance) • Accidents (effects on the environment and society) • Risk-based evaluation is used for some aspects of the nuclear fuel cycle design today

23. Innovations in Civil Engineering(DOE NP2010 Initiative) • Over the past 30 years civil engineering did not stand still: • Technologies ready for deployment • New and promising technologies worthy of additional exploration and development • Note: this is just the CE side! • No NE-CE-ME synergies were explored

24. Response modification devices Steel-plate sandwich structures Advanced concrete admixtures Composite plastics for reinforcement Pipe bends vs. welded elbows Precision blasting for rock removal High-deposition rate and robotic welding Cable splicing 4-D modeling and BIM GPS use in construction Open-top installation Ready-to-Use CE Technologies

25. Prefabrication, preassembly and modularization Advanced information management and control during design and construction Upcoming CE Technologies

26. Large weight, often positioned high above the foundation Combat inertia forces through: Strength Flexibility Damping Earthquake Engineering of Heavy Structures

27. Steel plate used as: Form Reinforcement Steel-plate Sandwich Walls

28. Steel plate used as: Form Reinforcement Composite action with concrete enabled using studs Steel-plate Sandwich Walls

29. Steel plate used as: Form Reinforcement Composite action with concrete enabled using studs Limited damage Steel-plate Sandwich Walls

30. Steel plate used as: Form Reinforcement Composite action with concrete enabled using studs Limited damage Steel-plate Sandwich Walls

31. Steel plate used as: Form Reinforcement Composite action with concrete enabled using studs Very strong Very ductilie, too! Steel-plate Sandwich Walls

32. Steel plate used as: Form Reinforcement Modular, prefabricated components Rapid construction Steel-plate Sandwich Walls

33. Devices designed to alter dynamic response of structures: Base isolation, to reduce input motion/energy Added damping, to dissipate energy that enters the structure Response Modification Devices

34. Provide a soft, deformable layer between the structure and the ground Not new! Sanjusangendo Temple in Kyoto, built in 1164 Base Isolation Concept

35. Base Isolation Concept

36. Base Isolation Benefits • Reduced motion of the structure • Reduced acceleration of the content

37. Base Isolation Benefits • Reduced motion of the structure • Reduced acceleration of the content • Problems: • Vertical acceleration • Seismic gap • Crossing the gap

38. Base Isolation Benefits • Reduced motion of the structure • Reduced acceleration of the content • Problems: • Vertical acceleration • Seismic gap • Crossing the gap

39. Technology developed in 1980’s Used in non-nuclear but safety-critical structures: LNG tanks Hospitals Emergency command centers Base Isolation Devices:Laminated Rubber Bearings

40. Technology developed in 1990’s Used in conventional building structures Used in critical infrastructure: Bay Area long-span bridge crossings Off-shore platforms Base Isolation Devices:Friction-Pendulum Bearings

41. Response Modification Devices: Seismic Dampers Oil damper Steel damper Lead damper Friction damper

42. Why Design Based on Performance? • Integrate the entire nuclear fuel cycle design to enable transparent risk-informed decisions on: • Safety • Security • Economy • Effects on the environment (sustainability)

43. Safety, Security, Economy and Sustainability • Use simulation to evaluate effects of hazards: • Anticipate before we build them • Balance safety and economy: • Do what is necessary, no more, no less • Find the sweet spots where small investments result in significant benefits • Integrate security and sustainability: • Design right from the get-go • Reduce carbon emissions during construction, too! • Be modular, reuse and recycle

44. How Do We Get There? • A unique opportunity is here: • A new building cycle is starting • There is little institutional memory left: • Bad: there is no experience • Good: there is no experience! • Form cross-disciplinary engineering teams as early as possible: • State performance objectives, not prescriptions • Work together to formulate the design process and execute it right!

45. Role of Civil/Structural Engineering • Performance-based design: • Utilize advances in conventional design to energize new nuclear construction • Bridge the engineering skill gap in structural and earthquake engineering • New and emerging technologies: • Response modification devices • New composite structural systems • Modular construction and maintenance • Modern construction and life cycle management

46. Thank you! Bozidar Stojadinovic, Associate Professor 721 Davis Hall #1710 Department of Civil and Env. Engineering University of California, Berkeley Berkeley, CA 94720-1710 boza@ce.berkeley.edu http://www.ce.berkeley.edu/~boza