1. The Rackwitz Symposium - a Milestone in Structural Reliability

2. Program
09:50 Opening address Prof. Dr. Konrad Zilch , Prof. Dr. Ton Vrouwenvelder
10: :50 Technical Session I Prof. Dr. Peter Schiessl
Prof. Dr. Konrad Zilch
10: :10 Coffee break
11: :30 Technical Session II
Prof. Dr. Ove Ditlevsen
Prof. Dr. John D. Sørensen
Prof. Dr. Ton Vrouwenvelder
12: :00 Lunch
14: :30 Technical Session III Prof. Dr. Fabio Casciati Prof. Dr. Michael H. Faber Prof. Dr. Mahesh Pandey
15: :00 Coffee break
16: :00 Closing Ceremony
Prof. Dr. Rüdiger Rackwitz, Prof. Dr. Konrad Zilch Prof. Dr. Michael H. Faber, Prof. Dr. Ton Vrouwenvelder
On Temporal and Spatial Probabilistic Engineering Modeling

3. On Temporal and Spatial Probabilistic Engineering Modeling
Rackwitz Symposium November 24, 2006
On Temporal and Spatial Probabilistic Engineering Modeling
M. H. Faber Chair of Risk and Safety Institute of Structural Engineering, ETH
Swiss Federal Institute of Technology, Zurich

4. Contents of Presentation
Preamble and Disclaimer
The Context of Engineering Decision Making
A Basic Framework for Decision Making
Recent Developments in Systems Modeling - System modeling in risk assessment - Exposure analysis in regard to rockfall - Vulnerability of concrete structures - Robustness of structures - Large scale earthquake risk management
Concluding Remarks
On Temporal and Spatial Probabilistic Engineering Modeling

5. Preamble and Disclaimer
This page was intentional left blank !
On Temporal and Spatial Probabilistic Engineering Modeling

6. The Context of Engineering Decision Making
What do engineers do ?
Hoover Dam - USA
On Temporal and Spatial Probabilistic Engineering Modeling

7. The Context of Engineering Decision Making
What do engineers do ?
Big Dig Boston/USA
On Temporal and Spatial Probabilistic Engineering Modeling

8. The Context of Engineering Decision Making
What do engineers do ?
Hong Kong Island - China
On Temporal and Spatial Probabilistic Engineering Modeling

9. The Context of Engineering Decision Making
What are we up against?
Corrosion
Fatigue
On Temporal and Spatial Probabilistic Engineering Modeling

10. The Context of Engineering Decision Making
What are we up against?
Tornados and strong winds
On Temporal and Spatial Probabilistic Engineering Modeling

11. The Context of Engineering Decision Making
What are we up against?
Earthquakes
On Temporal and Spatial Probabilistic Engineering Modeling

12. The Context of Engineering Decision Making
What are we up against?
Earth slide
Rock fall
On Temporal and Spatial Probabilistic Engineering Modeling

13. The Context of Engineering Decision Making
What are we up against?
Fires
Explosions
On Temporal and Spatial Probabilistic Engineering Modeling

14. The Context of Engineering Decision Making
What are we up against?
Over load
Design error
On Temporal and Spatial Probabilistic Engineering Modeling

15. The Context of Engineering Decision Making
What are we up against?
Bombs
Airplane impacts
On Temporal and Spatial Probabilistic Engineering Modeling

16. The Context of Engineering Decision Making
In what way are we important for society?
Human
capital
Natural resources
Protection of
the environment
Production
Life
safety
Development and maintenance of
infra-structure
Economy
On Temporal and Spatial Probabilistic Engineering Modeling

17. A Basic Framework for Decision Making
What is the basis for decision making?
Ranking of decision alternatives according to expected utility
Expected Utility
Probability of Outcome
Marginal Utility
On Temporal and Spatial Probabilistic Engineering Modeling

18. A Basic Framework for Decision Making
How do engineers make decisons?
Actions
Actions
Actions
Models of real world
Models of real world
Models of real world
Real World
Real World
Real World
Indicators
On Temporal and Spatial Probabilistic Engineering Modeling

19. A Basic Framework for Decision Making
What must be accounted for in engineering modeling? - Preferences (aim, purpose) - Consequences (states of marginal utility) - Uncertainties (aleatory and epistemic) - Temporal and spatial variations/dependencies - Options for decision making
System understanding !
On Temporal and Spatial Probabilistic Engineering Modeling

20. Recent Developments in Systems Modeling
How are consequences generated?
Exposure
Event
Event generated consequences
System change
On Temporal and Spatial Probabilistic Engineering Modeling

21. Recent Developments in Systems Modeling
How are consequences generated?
On Temporal and Spatial Probabilistic Engineering Modeling

22. Recent Developments in Systems Modeling
Modeling of consequences may be facilitated by explicitly accounting for:
Direct consequences
In-direct consequences
Needs more emphasis
Explicit treatment of epistemic uncertainty indicates where collection of additional knowledge may be beneficial
On Temporal and Spatial Probabilistic Engineering Modeling

23. Recent Developments in Systems Modeling
Engineered systems exhibit generic characteristics
On Temporal and Spatial Probabilistic Engineering Modeling

24. Recent Developments in Systems Modeling
Engineered systems exhibit generic characteristics
Actions
Actions
Actions
Models of real world
Models of real world
Models of real world
Real World
Real World
Real World
Risk reduction measures
Risk reduction measures
Exposure
Exposure
Exposure
Exposure
Exposure
Exposure
Indicators
Indicators
Risk reduction measures
Risk reduction measures
Risk reduction measures
Risk reduction measures
Vulnerability
Vulnerability
Vulnerability
Vulnerability
Vulnerability
Vulnerability
Indicators
Indicators
Indicators
Indicators
Robustness
Robustness
Robustness
Robustness
Robustness
Robustness
On Temporal and Spatial Probabilistic Engineering Modeling

25. Recent Developments in Systems Modeling
Exposure analysis in regard to rockfall
On Temporal and Spatial Probabilistic Engineering Modeling

26. Recent Developments in Systems Modeling
Exposure analysis in regard to rockfall
On Temporal and Spatial Probabilistic Engineering Modeling

27. Recent Developments in Systems Modeling
Exposure analysis in regard to rockfall
On Temporal and Spatial Probabilistic Engineering Modeling

28. Recent Developments in Systems Modeling
Exposure analysis in regard to rockfall
Detachment modeling
Fall modeling
On Temporal and Spatial Probabilistic Engineering Modeling

29. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard chlorides
On Temporal and Spatial Probabilistic Engineering Modeling

30. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard chlorides
On Temporal and Spatial Probabilistic Engineering Modeling

31. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard chlorides
On Temporal and Spatial Probabilistic Engineering Modeling

32. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides
Zone A
Zone B
On Temporal and Spatial Probabilistic Engineering Modeling

33. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides
Zone B
a. Component sector
b. Basic inspection
c. Model assessment
Density function
Correlation radius r
d. Idealization r r
On Temporal and Spatial Probabilistic Engineering Modeling

34. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides How does
deterioration
develop over time
and space?
On Temporal and Spatial Probabilistic Engineering Modeling

35. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides
Effect of inspection for one zone
On Temporal and Spatial Probabilistic Engineering Modeling

36. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides
Effect of inspection of several zones
On Temporal and Spatial Probabilistic Engineering Modeling

37. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides Effect of maintenance on life cycle costs
On Temporal and Spatial Probabilistic Engineering Modeling

38. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides Repair optimization How large a
proportion of the
surface should
exhibit initiated
corrosion before repair?
On Temporal and Spatial Probabilistic Engineering Modeling

39. Recent Developments in Systems Modeling
Vulnerability of concrete structures in regard to chlorides Acceptance criteria for new structures What can be accepted in terms of spatial variability of material characteristics?
On Temporal and Spatial Probabilistic Engineering Modeling

40. Recent Developments in Systems Modeling
Robustness of structures
On Temporal and Spatial Probabilistic Engineering Modeling

41. Recent Developments in Systems Modeling
Robustness of structures
An assessment framework
Exposure
Exposure
On Temporal and Spatial Probabilistic Engineering Modeling

42. Recent Developments in Systems Modeling
Robustness of structures
An assessment framework
Exposure
On Temporal and Spatial Probabilistic Engineering Modeling

43. Recent Developments in Systems Modeling
Robustness of structures
Calculation of Risk
On Temporal and Spatial Probabilistic Engineering Modeling

44. Direct Risk + Indirect Risk
Recent Developments in Systems Modeling
Robustness of structures
Features of the proposed index - Assumes values between zero and one - Measures relative risk only - Dependent upon the probability of damage occurrence
- Dependent upon consequences
IRob =
Direct Risk
Direct Risk + Indirect Risk
On Temporal and Spatial Probabilistic Engineering Modeling

45. Recent Developments in Systems Modeling
The framework easily facilitates decision analysis - Choice of the physical system
- Choice of inspection and repair - Choices to reduce consequences
Robustness of structures
On Temporal and Spatial Probabilistic Engineering Modeling

46. Recent Developments in Systems Modeling
Robustness of structures
Parallel system with n elements
Subjected to different types of exposures
Perfect ductile / brittle
Load distribution after component failure
Element damage / system failure
The one element case represents series systems
Consequences of system failure is set equal to times the consequences of component failure
On Temporal and Spatial Probabilistic Engineering Modeling

47. Recent Developments in Systems Modeling
Robustness of structures
Number of components – ductile material
The greater the number of components, the more robust
One component – Small robustness
One component – Series system
On Temporal and Spatial Probabilistic Engineering Modeling

48. Recent Developments in Systems Modeling
Robustness of structures
Load variability – ductile material
Higher CoV leads to less robustness
Higher Cov increases the probability that the system fails if one component is damaged
Here uncorrelated resistance is assumed – Correlation has the same effect as reducing the number of components
On Temporal and Spatial Probabilistic Engineering Modeling

49. Recent Developments in Systems Modeling
Robustness of structures
Load variability – brittle material
No residual carrying capacity
Cascading system failure
The robustness is close to zero
Indirect risks are dominating
Probabilities for damage states are low – or failure consequences high
On Temporal and Spatial Probabilistic Engineering Modeling

50. Recent Developments in Systems Modeling
Large scale earthquake risk management
On Temporal and Spatial Probabilistic Engineering Modeling

51. Recent Developments in Systems Modeling
Large scale earthquake risk management
On Temporal and Spatial Probabilistic Engineering Modeling

52. Recent Developments in Systems Modeling
Large scale earthquake risk management
On Temporal and Spatial Probabilistic Engineering Modeling

53. Recent Developments in Systems Modeling
Large scale earthquake risk management
Liquifaction
On Temporal and Spatial Probabilistic Engineering Modeling

54. Recent Developments in Systems Modeling
Large scale earthquake risk management
Condition indicators for liquefaction susceptibility of silty and sandy soils
On Temporal and Spatial Probabilistic Engineering Modeling

55. Recent Developments in Systems Modeling
Large scale earthquake risk management
Vulnerability
in regard to
liquifaction
Locations of buildings and
soil measurements
On Temporal and Spatial Probabilistic Engineering Modeling

56. Recent Developments in Systems Modeling
Large scale earthquake risk management
Mean and coefficient of variation of conditional Standard Penetration Test (SPT) blowcounts (N1)60 simulations
(N1)60 is the SPT blow count normalized to an overburden
pressure of approximately 100 kPa and a hammer energy ratio of 60%.
On Temporal and Spatial Probabilistic Engineering Modeling

57. Recent Developments in Systems Modeling
Large scale earthquake risk management
Probability of liquefaction at the study site,
given a M=7.4 earthquake causing a PGA of 0.3g
On Temporal and Spatial Probabilistic Engineering Modeling

58. Recent Developments in Systems Modeling
Large scale earthquake risk management
Distribution of damage for a
M=7.5 earthquake
Damage State
Fully Operational
Operational
Life Safety
Near Collapse
Collapse
On Temporal and Spatial Probabilistic Engineering Modeling

59. Recent Developments in Systems Modeling
Large scale earthquake risk management
Total risks for a
M=7.5 earthquake
Total Risk [$]
0 – 200’000
200’000 – 400’000
400’000 – 600’000
600’000 – 800’000
On Temporal and Spatial Probabilistic Engineering Modeling

60. Concluding Remarks
The theory of structural reliability forms a solid basis for engineering decision making
Over the last 40 years nominal reliabilities have evolved into a quantitative foundation for risk based decision making
The practical impact of risk based decison making is very significant
The potential is, however, much larger
On Temporal and Spatial Probabilistic Engineering Modeling

61. Concluding Remarks
The problems of the present are very different to those years ago – methods and techniques are becoming less important – understanding and representation are becoming more important
Great challenges are still out there - spatial modeling/sampling of uncertain characteristics - accounting for dependencies in systems representations - consequence modeling/societal losses due to perception - sustainable decision making
On Temporal and Spatial Probabilistic Engineering Modeling

62. On Temporal and Spatial Probabilistic Engineering Modeling
Rackwitz Symposium November 24, 2006
On Temporal and Spatial Probabilistic Engineering Modeling
Thanks for your attention !
Swiss Federal Institute of Technology, Zurich