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5th International Disaster and Risk Conference IDRC 2014 Integrative Risk Management - The role of science, technology & practice 24-28 August 2014 in Davos, Switzerland

5th International Disaster and Risk Conference IDRC 2014 Integrative Risk Management - The role of science, technology & practice 24-28 August 2014 in Davos, Switzerland


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  • 1. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org A Multihazard View of Progressive Collapse Resistance for Enhancing Resilience of Society Mehrdad Sasani Department of Civil and Environmental Engineering Northeastern University Boston, MA, USA
  • 2. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org A Multihazard View of Progressive Collapse Resistance for Enhancing Resilience of Society Mehrdad Sasani Department of Civil and Environmental Engineering Northeastern University Boston, MA, USA
  • 3. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Engineering Community Resilience Resilience is defined as ability to prepare and plan for, absorb, recover from, or adapt to actual or potential adverse events within and across built environment, social, economic, and ecological domains (NAS, 2012) We touch on both engineering aspects of resilience and decision making approach for achieving community resilience • Engineering resilience, as it relates to evaluating performance of structures and infrastructures, comprises a subset of issues relevant to community resilience • Identifying strategies to improve community resilience is largely driven by engineering, economic and environmental sciences • Social agreement, however, will likely differ for different communities and it is important to have an adaptable framework for achieving resilient communities
  • 4. From Performance to Resilience Based Design 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Time to recovery (Consequence in terms of extent of damage and repair costs) Hazard Years ≡ No Collapse (Extreme) Months (High) Weeks (Medium) Days (Low) Extreme High Medium Low
  • 5. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Why is collapse resistance important? • There is a continuing effort to use risk-based (as opposed to uniform hazard-based) approaches in building codes (e.g. ASCE 7-10, 2010) • In seismic design, a uniform risk of collapse is now used as basis of new risk-targeted ground motion maps • Trauma caused by collapse of buildings is primary cause of deaths and injuries in most earthquakes (Coburn and Spencer, 2002) • Similarly for response to blasts, majority of 168 fatalities during 1995 bombing of Murrah Federal building were due to partial collapse of structure and not to direct blast effects (Unified Facilities Criteria, 2009)
  • 6. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Multihazard View (e.g. Seismic vs Blast) Important structural characteristics for collapse resistance • For seismic ground motions, structural deformation capacity and ductility are primary characteristics of importance (Sozen, 1981) • For a structure designed as ductile (special), lateral loads are 3/8th of those for an ordinary structure • In order to resist collapse following loss of columns (say due to blasts), however, the strength of the structure to redistribute gravity loads can become very important
  • 7.   m F m F 5th International Disaster and Risk Conference IDRC 2014 Gravity Load P Gravity Load ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland   www.grforum.org Multihazard View (e.g. Seismic vs Blast) P Equivalent SDOF system Front view of 3D structure Equivalent SDOF system Front view of 3D structure Sasani, M. and Sagiroglu, S., "Progressive collapse of RC structures: A multihazard perspective," Structural Journal, ACI, Vol. 105, No. 1, pp. 96-103, 2008.
  • 8. Strain Hardening Coefficient 5th International Disaster and Risk Conference IDRC 2014 40 30 20 10 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Multihazard View (e.g. Seismic vs Blast) 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Yield Force / Column Axial Force 0 Displacement Ductility Demand =0.03 =0.05 =0.1 =0.2 =0.4
  • 9. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Enhancing Resilience In order to evaluate current state of resilience and identify strategies for improving community resilience there is a need to consider: a. individual structures and infrastructures b. systems , such as transportation, communication, Water supply and distribution, health, and financial c. System of systems (i.e. community)
  • 10. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Enhancing Resilience For each level of multiple hazards, 1. Evaluate risks to individual components of each system (for instance a bridge within the transportation system or a power plant within the electric grid). 2. Express risks in terms of time to recovery, and percent functional, which should be conducted more importantly at system level, considering systems interaction 3. Identify and quantify other resilience metrics such as collapse likelihood, cost of repairs, as well as social and environmental impacts (as continuous or for simplicity as a discrete quantity) 4. Final and most important step is decision making
  • 11. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Enhancing Resilience • One approach to evaluate resilience is to consolidate its metrics so that community resilience can be measured and compared quantitatively, even by a single measure, such as cost. • Another approach is to avoid directly combining resilience metrics and instead categorizing and providing data about different metrics of resilience (including both quantitative, such as economic cost and time to recovery, and qualitative, such as social and environmental impacts data) to facilitate decision making by communities.
  • 12. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Enhancing Resilience Other Metrics
  • 13. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Enhancing Resilience Other Metrics
  • 14. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Conclusions • Representative engineering aspects of resilience is discussed in context of multiple hazards (e.g. seismic vs blast effects) • Importance of structural strength to redistribute gravity loads and resist collapse following severe hazards is demonstrated • While risk assessment based on sound engineering principles is required, it is not sufficient for decision making and social agreement • An approach is presented to help decision making process and achieving resilience goals considering communities’ resources and priorities
  • 15. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Relation to Post 2015 Framework for Disaster Risk Reduction This study can be considered in context of disaster risk reduction at 2 levels: 1. From specific structural engineering point of view, important structural characteristics relevant to resilience under multiple hazards must better understood to optimize use of limited resources in enhancing resilience. 2. From a general point of view, it is an effort to emphasize that resilience goals and objectives must be adaptable to societal priorities as opposed to being uniquely and strictly defined for all, leaving communities with the sense that: “We cannot achieve resilience.” Instead, provide them with an adaptable framework and options they can choose from. • Needs for Post 2015 Framework for Disaster Risk Reduction – Research is needed at both levels From an engineering point of view structural characteristics in context of multiple hazards must identified From a general point of view, research is neede3d to make resilience an achievable and relative goal
  • 16. 5th International Disaster and Risk Conference IDRC 2014 ‘Integrative Risk Management - The role of science, technology & practice‘ • 24-28 August 2014 • Davos • Switzerland www.grforum.org Acknowledgement Inputs and comments made by Professor Matthias Ruth is greatly appreciated.