Evaluating the risk of a terrorist attack on a cable-stayed bridge: a probabilistic, structural analysis based approach (original) (raw)
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Probabilistic terrorism risk assessment and risk acceptability for infrastructure protection
Australian Journal of Structural Engineering, 2012
In the decade since the events of 9/11 there has been renewed interest in understanding the risks of terrorism, and the effectiveness of counter-terrorism measures. Since there is uncertainty associated with terrorist threats, structural and system response, effectiveness of counter-terrorism and protective measures, and terrorists' ability to infl ict damage, then there is clearly a need for probabilistic approaches to assessing and mitigating terrorism risks. The paper reviews research projects related to probabilistic terrorism risk assessment and risk acceptability for infrastructure protection currently underway at The University of Newcastle. The review of probabilistic risk assessments are given for: (i) IED design and initiation, and predicting variability of time-pressure load history on infrastructure; (ii) reinforced-concrete structural systems; (iii) fullbody scanners used at airports in the United States; and (iv) buildings subject to a terrorist vehicleborne improvised explosive device. The illustrative examples will highlight research capabilities at the University of Newcastle and identify research challenges to be faced in the future.
The terrorist threat on bridges , and on the transportation system as a whole
2006
There are some similarities between seismic and blast effects on bridge structures: both major earthquakes and terrorist attacks/accidental explosions are rare events that can induce large inelastic deformations in the key structural components of bridges. Since many bridges are (or will be) located in areas of moderate or high seismic activity, and because many bridges are potential terrorist targets, there is a need to develop structural systems capable of performing equally well under both events. This paper presents the findings of research to establish a multi-hazard bridge pier concept capable of providing an adequate level of protection against collapse under both seismic and blast loading, and whose members’ dimensions are not very different from those currently found in typical highway bridges. A series of experiments on 1/4 scale multi-hazard bridge piers was performed. Piers were concrete-filled steel tube columns (CFST columns) with different diameters (D = 4”, 5” and 6”...
Methodology for Risk Assessment and Management of Critical Bridges
An important aspect of designing bridges for security in an economically feasible way is to have in place plans for evaluating the criticality of any one structure on the transportation network. Thus, in deciding how to allocate resources, bridges considered more essential to the transportation infrastructure, or those thought to be at higher risk for a terrorist attack, should be given priority in the implementation of protective measures over other less critical bridges. This paper describes methods of carrying out threat and vulnerability analyses and risk assessments. Once the risks to a given bridge have been assessed, measures may need to be taken to mitigate these risks if they are deemed unacceptable. These measures generally attempt to prevent an attack by increasing surveillance or limiting access, but they can also include actions to limit the effects of blast loads or procedures to aid in rescue and recovery. Usually, deterrence and prevention measures will provide the least expensive solution to mitigate risk initially. Therefore, a risk manager should consider implementing these measures for short-term risks before strengthening a structure is specified. Deterrence and prevention, however, may not always provide the most costeffective solution for long-term risks when considering life time costs, such as maintenance, replacement, personnel, and inspection costs.
Threat Mitigation Options in the Design of Cable-Stayed Bridges
Structures Congress 2014, 2014
Cable stayed bridges provide an efficient structural solution over a wide range of span lengths and as a structural form, are often used to build an iconic structure. Protecting them from threats, both malicious and accidental, presents a number of challenges. This paper presents a number of different mitigation decisions made as a consequence of Accident Threat and Vulnerability Assessment (ATVA), sometimes known as Risk and Vulnerability Assessment (RVA), in the design development of four cable stayed bridges currently under design or construction in the US, and for which the authors have knowledge of the design. Details about each bridge are provided for the purposes of comparison and are limited so as to maintain the confidentiality of the threat and vulnerability assessment of the specific bridges discussed. Key considerations discussed for the bridges include: (1) Main tower protection, (2) Deck stability, (3) Loss of cables, and (4) Fire protection.
Acceptable Risk Criteria for Infrastructure Protection
International Journal of Protective Structures, 2015
A AB BS ST TR RA AC CT T This paper reviews risk-based approaches to assessing the risk acceptability and cost-effectiveness of protective measures for infrastructure. The paper describes three risk acceptance criteria based on fatality risks, failure probabilities and net benefit assessment. These criteria can be applied to any item of infrastructure such as buildings, bridges, dams, offshore platforms, etc. and also applies to any manmade or natural hazard such as earthquakes, cyclones, terrorism, floods and so on. The decision support framework accompanying these risk acceptance criteria considers hazard and threat probabilities, value of human life, physical and indirect damages, risk reduction and protective measure costs. This has specific utility for the safety and economical design and assessment of new and existing protective structures against shock and impact loading. Risk assessments are conducted for a bridge over an inland waterway where the hazard is ship impact and a building subject to terrorist attack. The illustrative examples showed under what combination of risk reduction, and fatality and damage costs the fatality and failure risks would be acceptable, and when protective measures would be cost-effective.
Assessment of Terrorism Risk to Critical Infrastructures: The Case of a Power-Supply Substation
Applied sciences, 2020
This paper presents a novel approach for estimating the vulnerability level of critical infrastructure confronting potential terrorist threats and assessing the usefulness of various protection strategies for critical infrastructure (CI). A methodology, utilizing a combination of topological network analysis and game theory, is presented to evaluate the effectiveness of protection strategies for certain components in the infrastructure under various attack scenarios. This paper focuses on protective strategies that are based on different attack scenarios as well as on the connectivity of the critical infrastructure components. The methodology proposed allows optimization of protection strategies in terms of investment in critical infrastructure protection in order to reduce expenditures on local infrastructure protection or on a single critical infrastructure for small projects. A case study of a power-supply substation is included to validate the analytical framework. The results indicate that the framework is highly applicable to other types of critical infrastructures facing similar threats. The results suggest that when only terrorist attacks are considered, improving the robustness of CI has a much higher effectiveness and efficiency than improving CI redundancy. The research methodology in this paper can be applied to a wide range of critical infrastructures and systems that may be at risk from manmade extreme events.
Structural health and bridge security in a multihazard environment
Journal of Transportation Security, 2011
Structural Health Monitoring and multihazard considerations are being increasingly considered by the infrastructure owners and administrators for costeffective evaluation and management. Besides natural hazards, infrastructure security has also become an essential consideration due to threats faced globally by all the infrastructure owners. Structural behavior to natural hazards and progressive deterioration is quite different than when it is subjected to a security related hazard such as blast loading. Thus, the role of Structural Health Monitoring (SHM) under security related hazard is quite different in temporal scale, i.e., its role before, during, and after a security related hazard event. This role is not well understood or studied in the literature. This paper sheds some light on these topics based on expert opinions and these results will be helpful to the infrastructure and security communities in understanding the role of health monitoring and multiple hazards considerations to focus/prioritize their future efforts in this field.
International Journal of Protective Structures, 2010
A AB BS ST TR RA AC CT T This paper reviews risk-based approaches to assessing the risk acceptability and cost-effectiveness of protective measures for infrastructure. The paper describes three risk acceptance criteria based on fatality risks, failure probabilities and net benefit assessment. These criteria can be applied to any item of infrastructure such as buildings, bridges, dams, offshore platforms, etc. and also applies to any manmade or natural hazard such as earthquakes, cyclones, terrorism, floods and so on. The decision support framework accompanying these risk acceptance criteria considers hazard and threat probabilities, value of human life, physical and indirect damages, risk reduction and protective measure costs. This has specific utility for the safety and economical design and assessment of new and existing protective structures against shock and impact loading. Risk assessments are conducted for a bridge over an inland waterway where the hazard is ship impact and a building subject to terrorist attack. The illustrative examples showed under what combination of risk reduction, and fatality and damage costs the fatality and failure risks would be acceptable, and when protective measures would be cost-effective.
Terrorism Risks and Blast Damage to Built Infrastructure
Natural Hazards Review, 2006
There is increasing interest in the use of risk management techniques for assessing vulnerability of built infrastructure to the "new" ͑man-made͒ hazard of terrorism. As such, the various uncertainties and risks associated with terrorism must be quantified and then used as the basis for assessing the viability and relative benefits of different mitigation measures, such as the use of blast-resistant technologies and other protective measures. In this paper, a probabilistic risk assessment procedure is developed to predict risks of damage arising from blast damage to built infrastructure. Issues related to risk assessment, including the concept of "risk transfer" and comparisons with natural hazards, are also discussed. To illustrate the concepts described, a preliminary reliability analysis is conducted, where fragility and blast reliability curves are developed for common glazing systems subject to explosive blast. The probabilistic analyses include the uncertainties associated with blast modeling, glazing response, and glazing failure criteria, and these are used to assess the effectiveness of various glazing systems.