TY - CHAP A1 - Holicky, Milan A1 - Diamantidis, Dimitris A1 - Sýkora, Miroslav ED - de Wilde, W. P. ED - Hernández, S. ED - Kravanja, S. T1 - Economically optimum structural design BT - methodology and case study T2 - High Performance and Optimum Design of Structures and Materials III (HPSM/OPTI 2018) ; Ljubljana, Slovenia 11.07.2018 - 13.07.2018 N2 - Codes of practice aim to assure structures have acceptable risks to the public and the minimum total costs over the working life of a design. However, current codified criteria for structural design correspond to a broad range of reliability levels, specified for dissimilar reference periods even though their recalculation for different periods is uncertain due to unknown dependence of failure events in time. In this contribution, target reliability levels are specified on the basis of probabilistic risk optimization considering the objective function as a sum of various costs including effects of time to failure and discounting. A case study presents probabilistic optimization of the roof of a stadium for 4,000 spectators and illustrates the effect of the considered input parameters. Failure consequences and relative cost of safety measure are shown to be major factors affecting the optimum reliability level. Less important factors are the discount rate and working life. Large uncertainty in failure cost estimates seems to have only a marginal effect on derived optimum reliability levels. KW - failure consequences KW - risk acceptance KW - probabilistic optimization KW - target reliability, KW - stadium KW - total cost KW - working life Y1 - 2018 U6 - https://doi.org/10.2495/hpsm180151 SP - 143 EP - 153 PB - WIT ER - TY - CHAP A1 - Sýkora, Miroslav A1 - Holicky, Milan A1 - Diamantidis, Dimitris T1 - Target Reliability for Existing Civil Engineering Systems T2 - 2016 Second International Symposium on Stochastic Models in Reliability Engineering, Life Science and Operations Management (SMRLO), 15-18 Feb. 2016, Beer Sheva, Israel N2 - Specification of the target reliability levels is one of the key issues of the assessment of existing systems. ISO 2394:2015 indicate procedures for specification of the target reliability levels by optimisation of the total cost related to an assumed remaining working life of a structural system. These approaches are critically compared with human safety criteria and with recommendations of present standards. It appears that the requirement on the same target reliability levels for existing civil engineering systems as for newly designed is uneconomical. Decisions in the assessment can result in the acceptance of the actual state or in upgrade of the existing structure, two reliability levels are thus needed - the minimum level below which the structure is unreliable and should be upgraded, and the target level indicating an optimum upgrade strategy. When reliability of a system or its key component is verified (as compared to design of a common component), the target reliability index should be increased by about 0.5. KW - cost optimization KW - Economics KW - existing structural systems KW - human safety KW - ISO Standards KW - Optimization KW - Reliability engineering KW - safety KW - target reliability Y1 - 2016 U6 - https://doi.org/10.1109/SMRLO.2016.28 SP - 109 EP - 114 PB - IEEE ER - TY - CHAP A1 - Sýkora, Miroslav A1 - Markova, Jana A1 - Diamantidis, Dimitris T1 - Bayesian Network Application for the Risk Assessment of Existing Energy Production Units T2 - 2016 Second International Symposium on Stochastic Models in Reliability Engineering, Life Science and Operations Management (SMRLO), 15-18 Feb. 2016, Beer Sheva, Israel N2 - A Bayesian network is applied in this contribution in order to assess the risks of a selected production unit in a fossil power station. A general framework for the risk assessment of production units of a power station is presented first by implementing statistical methods and Bayesian networks. Special emphasis is given to the input data consisting of failure rates which are obtained on the basis of recorded data and expert judgements. The consequences of failure are divided into economical and human (societal): economic consequences include outages of key technological devices, societal consequences cover potential injuries and fatalities. Probabilistic risk assessment methods are applied to the selected production unit of a power station. The influence of the uncertainties in the considered technical parameters on the availability of the unit is assessed and the acceptance of the calculated availability represented through the mean value and the standard deviation is discussed. Societal risks given in terms of weighted injuries and fatalities are obtained and respective risk acceptance criteria are presented. Uncertainties affecting the risks are discussed. It appears that the proposed framework provides a valuable assessment of the influence individual devices and their components on availability and societal risk. For that purpose the used methodology, intentionally simplified for operational applications, includes important factors affecting risks of production units. It is concluded that Bayesian networks are a transparent method for the probabilistic risk assessment of complex technological systems. The results of the performed analyses can be easily updated when additional information becomes available as illustrated in characteristic examples. KW - Availability KW - Bayes methods KW - Bayesian networks KW - Economics KW - Power generation KW - Probabilistic logic KW - Production KW - Production unit KW - Risk analysis KW - Societal risk KW - Uncertainties KW - uncertainty Y1 - 2016 U6 - https://doi.org/10.1109/SMRLO.2016.116 SP - 656 EP - 664 PB - IEEE ER - TY - CHAP A1 - Diamantidis, Dimitris A1 - Sýkora, Miroslav T1 - Optimizing Monitoring - Implementation of Draft Guideline and Case Study of Roof Exposed to Snow Loads T2 - Proceedings of 40th IABSE Symposium : Tomorrow's Megastructures, Nantes, France, 19-21 September 2018 N2 - This contribution addresses the optimisation of monitoring and decision-making criteria regarding the future use of structures and the related implementation in modern guidelines. A summary of the state-of-practice reveals deficiencies that are addressed by prospective guidance for the anticipated updates of standards, providing a general methodology to obtain cost-optimal decisions using limit state design, probabilistic reliability analysis and cost estimates. The implementation of a draft guideline and the corresponding risk-based approach are illustrated in a full-scale case study dealing with the roof of a stadium located in Northern Italy. The results demonstrate the potential of using monitoring systems and probabilistic reliability analysis in order to support decisions regarding safety measures such as snow removal, or temporary closure of the stadium. KW - cost optimisation KW - decision making criteria KW - Eurocodes KW - monitoring KW - reliability analysis KW - snow load KW - stadium roof KW - standard Y1 - 2018 SN - 978-3-85748-161-1 U6 - https://doi.org/10.2749/nantes.2018.s27-27 PB - Curran Associates Inc CY - Red Hook, NY ER - TY - GEN A1 - Diamantidis, Dimitris T1 - Risk based acceptance and decision criteria for the transportation of hazardous materials T2 - 6th International Conference on Industrial and Hazardous Waste Management. - Chania,Crete 04.-07.09.2018 Y1 - 2018 ER - TY - CHAP A1 - Sýkora, Miroslav A1 - Diamantidis, Dimitris A1 - Holický, Milan A1 - Markova, Jana A1 - Charters Morais, Eduardo T1 - Compressive Strength of Historic Masonry based on Destructive and Non-Destructive Test Results T2 - Proceedings of the 3rd International Conference on Protection of Historical Constructions (PROHITECH'17), July 12-15, 2017, Lisbon, Portugal Y1 - 2017 UR - https://www.researchgate.net/publication/320016406_Compressive_Strength_of_Historic_Masonry_based_on_Destructive_and_Non-Destructive_Test_Results ER - TY - CHAP A1 - Diamantidis, Dimitris A1 - Lenzi, Daniele A1 - Sýkora, Miroslav T1 - Optimal decisions based on monitoring – case study of steel roof T2 - Proceedings of the Joint COST TU1402-TU1406 - IABSE WC1 Workshop, Zagreb 2-3 March 2017 N2 - Monitoring of structures and related decisions based on cost optimization are discussed in this contribution. Many research publications and experimental data are currently available on inspection and on monitoring and they represent the outcome of the remarkable work done. Not all the topics of interest are widely debated and implemented in standards. The current state-of-practice in standards is summarized and aspects to be included in future recommendations are proposed. The implementation of risk-based decisions is illustrated in a case study dealing with a stadium roof in Northern Italy. Snow actions are important especially in northern and mountainous regions where heavy snowfalls and related accumulation result to considerable loads. As the roof structure fails to comply with the requirements of Eurocodes, a permanent monitoring system has been installed to allow for real time evaluation of the reliability level of the structure. The system supplies the necessary information supporting immediate decisions on closure of the stadium in case of an extraordinary snow load. Cost-optimal decisions regarding the closure of the stadium are analysed based on a limit state function, on probabilistic models for the influencing parameters including measurement uncertainty, economic losses related to closure and failure consequences. The results demonstrate the potential of the use of the monitoring systems and probabilistic reliability analysis in order to support decisions and highlight the need for their implementation in future standards. KW - probabilistic methods KW - reliability analysis KW - reliability level KW - risk analysis KW - SHM KW - snow load KW - monitoring Y1 - 2017 U6 - https://doi.org/10.5592/CO/BSHM2017.4.7 SP - 4.7-1 EP - 4.7-7 ER - TY - CHAP A1 - Sýkora, Miroslav A1 - Diamantidis, Dimitris A1 - Holický, Milan A1 - Jung, Karel T1 - Target reliability for new and existing railway civil engineering structures T2 - Handbook of RAMS in Railway Systems : theory and practice N2 - The specification of target reliability levels and risk acceptance criteria is one of the key issues of design and reliability assessment of existing railway stru ctures including bridges, tunnels or secondary struc-ures like noise barriers. Target reliability levels obtained by optimisation of the total cost, related to a required working life of the structure, are critically compared with human safety criteria based on group risks, intended to avoid accidents with a large number of fatalitie s. Practical applications of the theoretical principles are demonstrated by the examples of a railway bridge, railway tunnel and road bridge over an important railway line. The examples illustrate on how probabilistic reliability analysis and risk optimisation can support decisions about alternative strategies to achieve the optimal designs complying with the requirements on human safety. The contribution reveals that target relia bility levels for civil engineering structures recommended in various normative documents are inconsistent in terms of the values and the criteria according to which the appropriate values are to be specified. The optimal target reliabilities from economic point of view primarily depend on failure consequences and costs of safety measures. Y1 - 2017 SN - 9781315269351 U6 - https://doi.org/10.1201/b21983-20 PB - CRC Press ER - TY - CHAP A1 - Diamantidis, Dimitris A1 - Holický, Milan A1 - Sýkora, Miroslav T1 - Target Reliability Levels Based on Societal, Economic and Environmental Consequences of Structural Failure T2 - Proceedings of the 12th International Conference on Structural Safety & Reliability (ICOSSAR 2017), 6-10 August 2017, Vienna, Austria N2 - Target reliability levels are derived by optimizing initial structural costs and considering three major types of potential consequences of structural failure: a) direct and indirect economic losses, b) societal consequences resulting from fatalities and injuries, and c) environmental impacts. The guidance on how to e stimate and combine these consequences is provided; societal consequences are expressed using the Life Quality Index (LQI) concept. The case study focused on a generic load-bearing member reveals that target reliability levels for structural design are commonly dominated by economic criteria. Y1 - 2017 UR - https://www.researchgate.net/publication/319123444_Target_Reliability_Levels_Based_on_Societal_Economic_and_Environmental_Consequences_of_Structural_Failure ER - TY - JOUR A1 - Sýkora, Miroslav A1 - Holicky, Milan A1 - Jung, Karel A1 - Diamantidis, Dimitris T1 - Human safety criteria for risk-based structural design JF - International Journal of Safety and Security Engineering N2 - Risk and reliability criteria are well established in many industrial sectors such as the offshore, chemi- cal or nuclear industries. Comparative risk thresholds have been specified to allow a responsible organization or regulator to identify activities, which impose an acceptable level of risk concerning the participating individuals, or society as a whole. The scope of this contribution is to present target reliability criteria based on acceptable human safety levels. Application of theoretical principles is illustrated by examples of railway engineering structures. Initially it is shown how civil engineering structures for which human safety criteria play a role are classified according to Eurocodes. Examples include bridges, tunnels or station buildings. The general concepts for risk acceptance are then briefly reviewed, particularly in their relation to the target reliability criteria. The distinction between the two types of criteria is made: group risk and the acceptance criterion based on the Life Quality Index LQI approach introduced by ISO 2394:2015. The differences between the criteria for new and existing structures are discussed. The application is illustrated by an example of a bridge crossing an important railway line. It appears that while benefits and costs of a private stakeholder or public authority are reflected by economic optimisation, the society should define the limits for human safety to achieve uniform risks for various daily-life activities and across different industrial sectors. Keywords: group risk, human safety, individual risk, Life Quality Index, railway, risk acceptance, structure, target reliability KW - individual risk KW - group risk KW - human safety KW - Life Quality Index KW - railway KW - risk acceptance KW - structure KW - target reliability Y1 - 2018 U6 - https://doi.org/10.2495/SAFE-V8-N2-287-298 VL - 8 IS - 2 SP - 287 EP - 298 PB - WIT Press ER -