The Rackwitz Symposium - a Milestone in Structural Reliability

Program 09:50 Opening address Prof. Dr. Konrad Zilch , Prof. Dr. Ton Vrouwenvelder 10:00 - 10:50 Technical Session I Prof. Dr. Peter Schiessl Prof. Dr. Konrad Zilch 10:50 - 11:10 Coffee break 11:10 - 12:30 Technical Session II Prof. Dr. Ove Ditlevsen Prof. Dr. John D. Sørensen Prof. Dr. Ton Vrouwenvelder 12:30 - 14:00 Lunch 14:00 - 15:30 Technical Session III Prof. Dr. Fabio Casciati Prof. Dr. Michael H. Faber Prof. Dr. Mahesh Pandey 15:30 - 16:00 Coffee break 16:00 - 17:00 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 100 times the consequences of component failure On Temporal and Spatial Probabilistic Engineering Modeling

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Concluding Remarks The problems of the present are very different to those 20-40 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

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