TY - JOUR A1 - Diamantidis, Dimitris A1 - Sýkora, Miroslav A1 - Lenzi, Daniele T1 - Optimising Monitoring: Standards, Reliability Basis and Application to Assessment of Roof Snow Load Risks JF - Structural Engineering International N2 - This paper addresses the optimisation of monitoring and decision-making criteria regarding the future use of structures. The current state of practice in standards and reliability framework are initially summarised. A general methodology for obtaining cost-optimal decisions is then presented on the basis of limit state design, probabilistic reliability analysis and cost estimates. The implementation of the risk-based approach is illustrated in a case study dealing with the roof of a stadium located in northern Italy. As the roof fails to comply with the requirements of the Eurocodes, the installation of a permanent monitoring system is recommended to allow for a real-time reliability assessment. The results demonstrate the potential of monitoring systems and probabilistic reliability analysis for supporting decisions regarding safety measures such as snow removal or temporary closure of the stadium, as well as reflecting the need to implement the discussed procedures in future standards. Y1 - 2018 U6 - https://doi.org/10.1080/10168664.2018.1462131 VL - 28 IS - 3 SP - 269 EP - 279 PB - Taylor&Francis ER - TY - CHAP A1 - Sýkora, Miroslav A1 - Holický, Milan A1 - Rózsás, Árpád A1 - Barnardo-Viljoen, Celeste A1 - Retief, Johan Verster A1 - Diamantidis, Dimitris T1 - Risk Based Design of Infrastructures under Extreme Actions due to Environmental Change T2 - Life-cycle of engineering systems: emphasis on sustainable civil infrastructure, Symposium of the International Association for Life-Cycle Civil Engineering (IALCCE), 2016, Delft N2 - Environmental and climate change is a global issue that will and has already impacted the frequency and intensity of natural hazards in many regions throughout the world. Consequently, the actions on structures will be changing and present design practices will need to be adapted to provide for reliable structures with service lifetimes spanning over decades and centuries. A submitted review of present environmental and climate change information is focused on the distinct, but complementary climatic conditions of Central Europe and South Africa. An outline of the basis of structural design accounting for extreme wind and snow loads is presented and recommendations for future risk-based design procedures are discussed. Issues to consider include: a) use of extreme value models; b) implementation of changes in distribution parameters to obtain extremes with long return periods; c) consideration of the rate of the change. The example of a representative structure illustrates the effects of climatic actions on structural reliability. It appears that uncertainties related to the lack of observations hinder drawing strong conclusions concerning appropriate modifications of design procedures due to environmental and climate change. Uncertainties in the prediction of environmental and climate change have a direct bearing on optimal levels of reliability and the subsequent derivation of design values. Y1 - 2018 PB - Taylor & Francis 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 - JOUR A1 - Sýkora, Miroslav A1 - Markova, Jana A1 - Diamantidis, Dimitris T1 - Bayesian network application for the risk assessment of existing energy production units JF - Reliability Engineering & System Safety N2 - The assessment of existing infrastructures in the energy sector is of great economic significance worldwide. Fossil power stations are reaching their design service life and rational decisions concerning extensions of service life, maintenance and replacements of devices should be based on updated information of the actual conditions of the energy devices and their components, and on cost-benefit analysis using risk analysis and probabilistic optimisation procedures. The contribution provides an integrated framework for probabilistic reliability and risk assessment of existing energy production units considering availability and human safety criteria. An extensive case study focused on risks of an energy production unit in a fossil power station is provided to support practical applications. A Bayesian network is thereby implemented to assess the risks of the selected production unit. Special emphasis is given to the input data consisting of failure rates obtained from recorded data and expert judgements. The influence of uncertainties in the considered performance indicators on the availability of the unit is analysed. It is shown that a reasonably simplified framework can provide a valuable assessment of the influence of individual devices and their components on availability and societal risk, identifying thus the major risk contributors. (C) 2017 Elsevier Ltd. All rights reserved. KW - Availability KW - Bayesian networks KW - Decision-making KW - design KW - Failure probability KW - FRAMEWORK KW - Optimization KW - Production unit KW - Risk analysis KW - Societal risk KW - SYSTEMS KW - Uncertainties Y1 - 2018 U6 - https://doi.org/10.1016/j.ress.2017.09.006 VL - 169 IS - January SP - 312 EP - 320 PB - Elsevier ER - TY - CHAP A1 - Boccara, R. A1 - Diamantidis, Dimitris A1 - Sýkora, Miroslav T1 - Optimal design of ground-mounted solar systems T2 - Safety and reliability : methodology and applications : proceedings of the European Safety and Reliability Conference, ESREL 2014, Wrocław, Poland, 14-18 September 2014 N2 - Solar energy represents a clean, natural and sustainable source of energy. Solar photovoltaic panels can be installed on roofs of structures or in the ground. This contribution focusses on ground-mounted systems, which are presently widely implemented. At present limited guidelines on the design of solar ground-mounted structures are available. Usually standards for the design of normal buildings are applied. However, the design of ground-mounted structures significantly differs from common structural design by: (1) a lower design lifetime (20-25 years) is accepted; (2) failure is not associated with the loss of human life; (3) resistance uncertainties need due attention; (4) uplift wind forces dominating structural reliability are associated with a large scatter. That is why the reliability analysis and optimal design of ground-mounted solar systems is investigated herein. The failure costs and especially their ratio to the initial costs are analyzed considering the data provided from the industry. Probabilistic reliability analyses are carried out and optimum design levels are computed for representative cost ratios. The optimal target reliability depends on the ratio between failure and initial costs; reliability index of 3.5 corresponds to a reasonable cost ratio of 10. KW - Dach KW - Montagesystem KW - Montiergerät KW - nachhaltiges Sourcing KW - Solarenergie KW - Solarmodul KW - Windkraft (Energiequelle) Y1 - 2014 SN - 978-1-138-02681-0 SP - 2175 EP - 2181 PB - CRC Press CY - Boca Raton 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 - JOUR A1 - Bazzurro, Paolo A1 - Cornell, C. A1 - Diamantidis, Dimitris A1 - Manfredini, Gian T1 - Seismic damage hazard analysis for requalification of nuclear power plant structures: methodology and application JF - Nuclear Engineering and Design N2 - A methodology for the evaluation of the annual probability of occurrence of post-elastic seismic damage in realistic structures is presented. The seismic damage hazard analysis (SDHA) is carried out here by coupling conventional seismic hazard analysis (SHA) for the site and the structural response to earthquakes of different intensities. The structural performance is statistically investigated by conducting appropriate non-linear dynamic analyses for a limited set of real ground-motion records that might potentially pose a threat to the structure at the site. The merging of these two approaches permits calculation of the seismic hazard faced by the structure in direct damage terms. The methodology is presented in this paper with the aid of a simple illustrative case study where the annual probability of damage and, eventually, failure of a power house steel structure is computed. This methodology can find practical applications in seismic retrofit of nuclear power plant structures and in the evaluation of seismic damage hazards in new structure designs. Y1 - 1996 U6 - https://doi.org/10.1016/0029-5493(95)01111-0 VL - 160 IS - 3 SP - 321 EP - 332 PB - Elsevier ER - TY - JOUR A1 - Diamantidis, Dimitris A1 - Holicky, Milan A1 - Sýkora, Miroslav T1 - Reliability and Risk Acceptance Criteria for Civil Engineering Structures JF - Transactions of the VSB - Technical University of Ostrava, Civil Engineering Series N2 - The specification of risk and reliability acceptance criteria is a key issue of reliability verifications of new and existing structures. Current target reliability levels in standards appear to have considerable scatter. Critical review of risk acceptance approaches to societal, economic and environmental risk indicates that an optimal design strategy is mostly dominated by economic aspects while human safety aspects need to be verified only in special cases. It is recommended to specify the target levels considering economic optimisation and the marginal life-saving costs principle, as both these approaches take into account the failure consequences and costs of safety measures. KW - Abnahmekriterium KW - Bauingenieurwesen KW - Kosten KW - Sicherheitsmaßnahme KW - Umweltrisiko KW - Zuverlässigkeit Y1 - 2016 UR - https://www.researchgate.net/publication/312424896_Reliability_and_Risk_Acceptance_Criteria_for_Civil_Engineering_Structures VL - 16 IS - 2 SP - 1 EP - 10 PB - De Gruyter ER - TY - CHAP A1 - Sýkora, Miroslav A1 - Diamantidis, Dimitris A1 - Masciotta, Maria Giovanna T1 - Optimising In-situ Testing for Historic Masonry Structures: a Case Study T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019): Durability, Monitoring and Repair of Structures, 20-22 March 2019, Rovinj, Croatia N2 - Masonry structures were built by means of various techniques, using materials whose properties exhibit a considerable scatter depending on the period of construction, region- specific soil resources and manufacturing procedures. Significant spatial variability within the structural system is often observed due to diverse deterioration mechanisms. Therefore, it is important to obtain case-specific information on the mechanical properties of existing masonry structures. The case study of a historic building illustrates how the number of destructive tests (DTs) used to calibrate non-destructive tests (NDTs) can be optimised for the reliability assessment. Calibrated NDTs are used to establish the probabilistic model for compressive masonry strength. The specific focus is on compressive strength of masonry units; tests of mortar strength are only briefly discussed. The preliminary assessment is based on non-calibrated NDTs. The number of DTs for calibration is then optimised by means of probabilistic cost optimisation, considering also possible subsequent actions – ‘do nothing’ or ‘strengthen the structure’. It appears that the estimates of masonry unit strength based on NDTs are associated with large dispersion and may be significantly biased. Consequently, it is often beneficial to conduct at least one DT. A practical tool is provided to determine optimum number of DTs for different outcomes of a NDT survey and different failure consequences. Y1 - 2019 UR - www.researchgate.net/publication/332447762_Optimising_In-situ_Testing_for_Historic_Masonry_Structures_a_Case_Study SN - 978-2-35158-217-6 SN - 978-2-35158-218-3 SP - 684 EP - 691 PB - RILEM Publications SARL ER - TY - CHAP A1 - Diamantidis, Dimitris A1 - Sýkora, Miroslav T1 - Implementing Information Gained through Structural Health Monitoring – Proposal for Standards T2 - 13th International Conference on Applications of Statistics and Probability in Civil Engineering, Mai 2019, Seoul, Korea N2 - With exception of a few issues such as design by testing, current standards do not include guidelines on the use and the quantification of value of additional information gained through Structural Health Monitoring (SHM). This contribution summarizes a recently developed draft of the guideline for practicing engineers in the framework of the EU-COST project 1402 and illustrates its application in engineering decision-making. Besides continuous and periodic monitoring, visual inspection, non-destructive evaluation and proof loading are included herein as a simple form of SHM. The guideline is independent of a type of structure, construction materials, loading, and of environmental conditions. It aims at a wide field of application including design of new structures, assessment of existing structures and type specific monitoring of a population of structures. The decision process related to the use of SHM is presented first together with relevant decision objectives and variables. Performance indicators are summarized and discussed with respect to the performance objectives. The evaluation of monitoring strategies based on life cycle costs is exposed and the selection of optimal intervention actions including safety measures is shown in representative case studies. The results demonstrate the potential of the use of monitoring to support engineering decisions and reflect though the practical benefits from the application of the guideline. Y1 - 2019 UR - https://www.researchgate.net/publication/333578633_Implementing_Information_Gained_through_Structural_Health_Monitoring_-Proposal_for_Standards ER -