@article{SykoraHolickyJungetal., author = {S{\´y}kora, Miroslav and Holicky, Milan and Jung, Karel and Diamantidis, Dimitris}, title = {Human safety criteria for risk-based structural design}, series = {International Journal of Safety and Security Engineering}, volume = {8}, journal = {International Journal of Safety and Security Engineering}, number = {2}, publisher = {WIT Press}, doi = {10.2495/SAFE-V8-N2-287-298}, pages = {287 -- 298}, abstract = {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}, language = {en} } @article{HolickySykoraDiamantidis, author = {Holicky, Milan and S{\´y}kora, Miroslav and Diamantidis, Dimitris}, title = {Reliability levels related to different reference periods and consequence classes}, series = {Beton- und Stahlbetonbau}, volume = {113}, journal = {Beton- und Stahlbetonbau}, number = {S2, Supplement: 16th International Probabilistic Workshop}, publisher = {Ernst \& Sohn, a Wiley Brand}, doi = {10.1002/best.201800039}, pages = {22 -- 26}, abstract = {The target reliability levels recommended in various national and international documents for new and existing structures are quite different and vaguely related to types of structures and consequences of failure. The optimum reliability levels can be obtained by considering the total expected cost of the structure over the design working life. Indicative values of reliability indexes are given in EN 1990 (2002) for two reference periods, 1 year and 50 years. The annual target reliability levels βt1 are presently indicated in the recent draft of EN 1990 (2017) without any explicit link to different reference period or design working life. When determining the target reliability index for the reference period of n years that generally differs from the design working life, correlation of failure events in subsequent years should be taken into account. Considering the annual reliability index β1 an approximate formula is proposed for the reliability index βnk related to the reference period of n years and independence interval of k years. The independence interval k ≤ n corresponds to the mean time period in years for which the failures in subsequent periods of k years are assumed to be mutually independent. The operational use of the proposed formula is clarified by practical tools. The reliability differentiation reflected in consequence classes is also discussed in this contribution.}, language = {en} } @inproceedings{DiamantidisSykoraBertacca, author = {Diamantidis, Dimitris and S{\´y}kora, Miroslav and Bertacca, Elena}, title = {Obsolescence Rate: Framework, Analysis and Influence on Risk Acceptance Criteria}, series = {6th International Symposium on Life-Cycle Civil Engineering (IALCCE), Ghent, Belgium}, booktitle = {6th International Symposium on Life-Cycle Civil Engineering (IALCCE), Ghent, Belgium}, abstract = {Buildings are major long lasting assets of the society and business enterprises and form a significant part of infrastructure management. They require continual maintenance and in many cases they can become inap-propriate for their original purpose due to obsolescence and are demolished. The present contribution ex-plores the obsolescence of buildings and in particular the definitions of obsolescence, the related influenc-ing factors and the associated uncertainties. Thereby definitions of the obsolescence rate based on the physi-cal and useful (service) life are clarified. The experienced useful life of buildings in Finland, Germany and North America is statistically analysed, utilizing available databases, and comparisons with the design (minimum) working life specified in standards are made. The probability of not exceeding the required min-imum service life is evaluated and discussed. Whereas many factors affecting the obsolescence rate are be-yond the control of civil engineers, particular attention needs to be paid to cases where the service life of the structure is determined by physical aspects related to deterioration. These cases are identified and recom-mendations to improve structural design are offered. The service life and the related renewal rate is influ-encing the risk acceptance criteria as given in ISO 2394. Such criteria are derived on the basis of economic optimization and the LQI marginal safety costs principle. A statistical model for the renewal rate is obtained and its influence on the target reliability is investigated for a representative failure limit state. The influence of the obsolescence rate is quantified and critically disputed.}, language = {en} } @article{SteenbergenRaphaelDJMSykoraDiamantidisetal., author = {Steenbergen, Raphael D. J. M., and S{\´y}kora, Miroslav and Diamantidis, Dimitris and Holicky, Milan and Vrouwenvelder, Ton}, title = {Economic and human safety reliability levels for existing structures}, series = {Structural concrete}, volume = {16}, journal = {Structural concrete}, number = {3}, publisher = {Ernst \& Sohn, a Wiley brand}, doi = {10.1002/suco.201500022}, pages = {323 -- 332}, abstract = {Specifying the target reliability levels is one of the key issues in the assessment of existing structures. For a majority of existing buildings and infrastructures, the design life has been reached or will be reached in the near future. These structures need to be reassessed in order to verify their safety. Eurocodes provide a general basis primarily intended for the design of new structures, but the basic principles can be used for assessing existing buildings, too. Reliability levels are generally based on both economic optimization and criteria for human safety. In this study, both methods are elaborated for existing structures. It appears that the requirement for the same target reliability for existing and new structures is uneconomical. Further, cost optimization seems to yield rather low reliability levels and human safety criteria often become the critical factor. The study concludes with practical guidelines for establishing reliability indices for existing structures linked to Eurocode principles.}, language = {en} } @inproceedings{DiamantidisLenziSykora, author = {Diamantidis, Dimitris and Lenzi, Daniele and S{\´y}kora, Miroslav}, title = {Optimal decisions based on monitoring - case study of steel roof}, series = {Proceedings of the Joint COST TU1402-TU1406 - IABSE WC1 Workshop, Zagreb 2-3 March 2017}, booktitle = {Proceedings of the Joint COST TU1402-TU1406 - IABSE WC1 Workshop, Zagreb 2-3 March 2017}, doi = {10.5592/CO/BSHM2017.4.7}, pages = {4.7-1 -- 4.7-7}, abstract = {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.}, language = {en} } @inproceedings{DiamantidisSykora, author = {Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Optimizing Monitoring - Implementation of Draft Guideline and Case Study of Roof Exposed to Snow Loads}, series = {Proceedings of 40th IABSE Symposium : Tomorrow's Megastructures, Nantes, France, 19-21 September 2018}, booktitle = {Proceedings of 40th IABSE Symposium : Tomorrow's Megastructures, Nantes, France, 19-21 September 2018}, publisher = {Curran Associates Inc}, address = {Red Hook, NY}, isbn = {978-3-85748-161-1}, doi = {10.2749/nantes.2018.s27-27}, pages = {8}, abstract = {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.}, language = {en} } @inproceedings{DiamantidisHolickySykora, author = {Diamantidis, Dimitris and Holick{\´y}, Milan and S{\´y}kora, Miroslav}, title = {Target Reliability Levels Based on Societal, Economic and Environmental Consequences of Structural Failure}, series = {Proceedings of the 12th International Conference on Structural Safety \& Reliability (ICOSSAR 2017), 6-10 August 2017, Vienna, Austria}, booktitle = {Proceedings of the 12th International Conference on Structural Safety \& Reliability (ICOSSAR 2017), 6-10 August 2017, Vienna, Austria}, abstract = {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.}, language = {en} } @inproceedings{HolickyDiamantidisSykora, author = {Holick{\´y}, Milan and Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Effects of Quality Control on Reliability of Reinforced Concrete Structures according to Eurocodes}, series = {fib Symposium 2016 : Performance-Based Approaches for Concrete Structures, 14, 2016, Cape town}, booktitle = {fib Symposium 2016 : Performance-Based Approaches for Concrete Structures, 14, 2016, Cape town}, abstract = {The effect of quality control on structural reliability represents an increasingly important concern of designers and thus is investigated in this contribution, focusing on reinforced concrete structures. Recent European documents for structural design - Eurocodes, fib Model Code 2010 and ISO 2394:2015 for general principles on structural reliability indicate that the partial factors may be adjusted to available information on the quality control of structures. In particular, the partial factors for concrete and steel strength may be significantly reduced taking into account actual execution quality and related available data. Using probabilistic methods of structural reliability, effects for execution quality are investigated in this contribution considering two fundamental reinforced concrete members: a beam (or slab) exposed to bending and a short column exposed to compression. It is shown that the reliability of reinforced concrete members may vary with the load ratio of variable and permanent actions. It appears also that the structural members of a basic quality, designed using unreduced partial factors, have a greater reliability level than the members of an increased quality, designed using the partial factors reduced according to EN 1992 1 1. This provides the basis for recommendations for further code developments.}, language = {en} } @inproceedings{SykoraDiamantidis, author = {S{\´y}kora, Miroslav and Diamantidis, Dimitris}, title = {Snow Load Monitoring - Measure to Control Reliability of the Roof of a Stadium}, series = {International Conference Structural Reliability \& Modelling in Mechanics, 24.-25.05.2018, Ostrava, Czech Republic}, booktitle = {International Conference Structural Reliability \& Modelling in Mechanics, 24.-25.05.2018, Ostrava, Czech Republic}, abstract = {This contribution shows how monitoring can be used to control reliability of a structure not complying with the requirements of Eurocodes. A general methodology to obtain cost-optimal decisions using limit state design, probabilistic reliability analysis and cost estimates is utilised in a full-scale case study dealing with the roof of a stadium located in Northern Italy. The results demonstrate the potential of monitoring systems and probabilistic reliability analysis to support decisions regarding safety measures such as snow removal, or temporary closure of the stadium.}, language = {en} } @inproceedings{SykoraHolickyDiamantidis, author = {S{\´y}kora, Miroslav and Holicky, Milan and Diamantidis, Dimitris}, title = {Target Reliability for Existing Civil Engineering Systems}, series = {2016 Second International Symposium on Stochastic Models in Reliability Engineering, Life Science and Operations Management (SMRLO), 15-18 Feb. 2016, Beer Sheva, Israel}, booktitle = {2016 Second International Symposium on Stochastic Models in Reliability Engineering, Life Science and Operations Management (SMRLO), 15-18 Feb. 2016, Beer Sheva, Israel}, publisher = {IEEE}, doi = {10.1109/SMRLO.2016.28}, pages = {109 -- 114}, abstract = {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.}, language = {en} } @inproceedings{SykoraMarkovaDiamantidis, author = {S{\´y}kora, Miroslav and Markova, Jana and Diamantidis, Dimitris}, title = {Bayesian Network Application for the Risk Assessment of Existing Energy Production Units}, series = {2016 Second International Symposium on Stochastic Models in Reliability Engineering, Life Science and Operations Management (SMRLO), 15-18 Feb. 2016, Beer Sheva, Israel}, booktitle = {2016 Second International Symposium on Stochastic Models in Reliability Engineering, Life Science and Operations Management (SMRLO), 15-18 Feb. 2016, Beer Sheva, Israel}, publisher = {IEEE}, doi = {10.1109/SMRLO.2016.116}, pages = {656 -- 664}, abstract = {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.}, language = {en} } @inproceedings{HolickyDiamantidisSykora, author = {Holicky, Milan and Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Economically optimum structural design}, series = {High Performance and Optimum Design of Structures and Materials III (HPSM/OPTI 2018) ; Ljubljana, Slovenia 11.07.2018 - 13.07.2018}, booktitle = {High Performance and Optimum Design of Structures and Materials III (HPSM/OPTI 2018) ; Ljubljana, Slovenia 11.07.2018 - 13.07.2018}, editor = {de Wilde, W. P. and Hern{\´a}ndez, S. and Kravanja, S.}, publisher = {WIT}, doi = {10.2495/hpsm180151}, pages = {143 -- 153}, abstract = {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.}, language = {en} } @inproceedings{CroceDiamantidisSykora, author = {Croce, Valeria and Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Seismic Damage Evaluation and Decisions on Interventions Supported by UAV-Based Surveys}, series = {Protection of Historical Constructions: Proceedings of PROHITECH 2021}, volume = {209}, booktitle = {Protection of Historical Constructions: Proceedings of PROHITECH 2021}, editor = {Vayas, Ioannis and Mazzolani, Federico M.}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-030-90787-7}, doi = {10.1007/978-3-030-90788-4_20}, pages = {206 -- 221}, abstract = {The contribution demonstrates the benefits of Unmanned Aerial Vehicles (UAV)-based surveys for building damage evaluation and decisions on interventions after an earthquake. The case study focuses on the historic village of Castelluccio di Norcia (Italy), heavily damaged by the 2016 earthquake. By constructing a 3D model based on UAV flights, the damage levels are estimated for buildings in the village and an optimal set of intervention measures is proposed. For the decision analysis, a pre-posterior Bayesian technique is utilized. The efficiency of the UAV-based survey is highlighted through a cost-benefit analysis and by considering parameters such as the time constraints, the quality of obtained data and the risk of inspecting persons. The proposed method seems to be efficient in organizing rescuing activities, managing emergency measures and specifying interventions, following the occurrence of an accidental situation.}, language = {en} } @inproceedings{CroceDiamantidisSykora, author = {Croce, Valeria and Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Planning post earthquake surveys: assessments and reconstruction of small historical centres}, series = {1st IABSE Online Symposium 2020, Synergy of culture and civil engineering - history and challenges: Wrocław, Poland, 7-9 October 2020, Proceedings}, booktitle = {1st IABSE Online Symposium 2020, Synergy of culture and civil engineering - history and challenges: Wrocław, Poland, 7-9 October 2020, Proceedings}, editor = {Bien, Jan}, publisher = {Curran Associates Inc}, address = {Red Hook, NY}, isbn = {978-1-7138-2387-2}, pages = {332 -- 339}, abstract = {The contribution presents a methodological procedure for the management and planning of interventions after earthquake events in small historic centres. Reference is made to the case study of Castelluccio di Norcia, a village in the Apennine Mountains affected by the seismic sequence that hit Central Italy in 2016. The earthquake risk of the area and the damaging events of 2016 are critically reviewed. The implementation of cognitive analysis and the application of advanced survey techniques involving the use of nmanned Aerial Vehicles (UAVs) for the purposes of emergency management and monitoring of damaged areas are analysed. The outcomes, combined with the direct involvement of the local population, represent a complete and integrated approach allowing the definition of a) possible intervention strategies, b) related decision criteria and c) practical recommendations for the reconstruction and regeneration of Castelluccio, and, in general, of small historic centres damaged by catastrophic events.}, language = {en} } @inproceedings{DiamantidisSykora, author = {Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Reliability Differentiation and Uniform Risk in Standards}, series = {Scientific Symposium Future Trends in Civil Engineering, Zagreb,Croatia, 17 October 2029}, booktitle = {Scientific Symposium Future Trends in Civil Engineering, Zagreb,Croatia, 17 October 2029}, doi = {10.5592/CO/FTCE.2019.11}, pages = {241 -- 260}, abstract = {Reliability of structures and infrastructures is a major issue in structural engineering. Structural standards have traditionally been mainly concerned with public safety preventing loss of life or injury; this view has been shifting in recent years towards minimisation of economic loss. This contribution discusses the reliability differentiation principle in modern standards. Its aim is to achieve uniform risk levels for the various classes of structures. Codified criteria for reliability differentiation and risk informed decisions inherent in standards and especially in the Eurocodes are critically reviewed. It is shown that the classification of structures based on consequences of failure is an approach that has not been widely implemented in everyday design. Practical rules for the classification and implementation in design are needed and related proposals are presented.}, language = {en} } @article{SykoraDiamantidisMuelleretal., author = {S{\´y}kora, Miroslav and Diamantidis, Dimitris and Mueller, Dominik and Sousa, Helder}, title = {A practical guide on the quantification of value of information gained by structural health monitoring and application to historic masonry structures}, series = {Structure and Infrastructure Engineering}, volume = {18}, journal = {Structure and Infrastructure Engineering}, number = {4}, publisher = {Taylor\&Francis}, doi = {10.1080/15732479.2020.1857793}, pages = {441 -- 455}, abstract = {Structural health monitoring (SHM) projects are mostly based on semi-empirical decisions, emphasising the importance of the structure and lacking a rational comparison of the benefits and costs. The present work offers guidance to overcome this, based on an objective framework using the quantification of the value of SHM in an engineering context. Firstly, procedures for practising engineers are outlined on the basis of the COST guidelines. Secondly, a case study, focused on the reliability of a historic masonry structure, demonstrates the optimisation of surveys based on non-destructive tests calibrated by destructive tests. Both the outlined procedures and case study are carefully prepared and in tune, so the reader can easily understand the feasibility of the framework. Decisions on the utilisation of SHM in practical applications can be effectively achieved based on the highest expected utility gained by SHM. For this, two scenarios are needed: (i) a scenario with at least one SHM strategy and (ii) a scenario without any SHM.}, language = {en} } @article{SykoraDiamantidisHolickyetal., author = {S{\´y}kora, Miroslav and Diamantidis, Dimitris and Holick{\´y}, Milan and Markov{\´a}, Jana and R{\´o}zs{\´a}s, {\´A}rp{\´a}d}, title = {Assessment of compressive strength of historic masonry using non-destructive and destructive techniques}, series = {Construction and Building Materials}, volume = {193}, journal = {Construction and Building Materials}, number = {December}, publisher = {Elsevier}, doi = {10.1016/j.conbuildmat.2018.10.180}, pages = {196 -- 210}, abstract = {Masonry structures were built by various techniques using different materials, the properties of which exhibit a considerable scatter dependent on periods of construction and region-specific conditions. For historic structures with a heritage value, various non- or minor-destructive tests (NDTs) are commonly applied, while the application of destructive tests (DTs) is minimized. The contribution is based on investigations of 15 historic stone and clay brick masonry structures, for which NDT strengths of masonry units are verified by DTs. The proposed operational approach makes it possible to account for statistical uncertainty due to a limited number of DTs used to calibrate NDTs.}, language = {en} } @inproceedings{DiamantidisSykora, author = {Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Implementing Snow Load Monitoring to control Reliability of a Stadium Roof}, series = {Transactions of VSB}, volume = {19}, booktitle = {Transactions of VSB}, number = {1}, publisher = {TECHNICAL UNIVERSITY OF OSTRAVA}, doi = {10.35181/tces-2019-0006}, pages = {35 -- 40}, abstract = {This contribution shows how monitoring can be used to control reliability of a structure not complying with the requirements of Eurocodes. A general methodology to obtain cost-optimal decisions using limit state design, probabilistic reliability analysis and cost estimates is utilised in a full-scale case study dealing with the roof of a stadium located in Northern Italy. The results demonstrate the potential of monitoring systems and probabilistic reliability analysis to support decisions regarding safety measures such as snow removal, or temporary closure of the stadium.}, language = {en} } @article{SykoraDiamantidisHolickyetal., author = {S{\´y}kora, Miroslav and Diamantidis, Dimitris and Holicky, Milan and Jung, Karel}, title = {Target reliability for existing structures considering economic and societal aspects}, series = {Structure and infrastructure engineering}, volume = {13}, journal = {Structure and infrastructure engineering}, number = {1}, publisher = {Taylor\&Francis}, doi = {10.1080/15732479.2016.1198394}, pages = {181 -- 194}, abstract = {Specification of target reliability levels is one of the key issues of the assessment of existing structures. ISO 13822:2010 and ISO 2394:2015 indicate procedures for specification of target reliability levels by optimisation of the total cost related to an assumed remaining working life of a structure. These approaches are critically compared with human safety criteria, with target levels based on a marginal life-saving costs principle, and with recommendations of present standards. Optimal target reliability levels are then derived in the representative case study for an existing structural member. It appears that the requirement to reach the same target reliability levels for existing and new structures is uneconomical. Decisions made in the assessment can result in the acceptance of the actual state or in the upgrade of an 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. It is recommended that these levels be established using economic optimisation and the marginal life-saving costs principle, as both the approaches take into account the costs of safety measures and the failure consequences.}, language = {en} } @article{SykoraHolickyDiamantidis, author = {S{\´y}kora, Miroslav and Holick{\´y}, Milan and Diamantidis, Dimitris}, title = {Probabilistic updating in the reliability assessment of industrial heritage structures}, series = {Heron}, volume = {59}, journal = {Heron}, number = {2/3}, publisher = {Stevin-Laboratorium, TU Delft}, address = {Delft}, issn = {0046-7316}, abstract = {Assessment of existing structures should be based on the actual as-built conditions concerning geometry, material properties, loading and environmental conditions. A crucial step of the assessment consists in updating of prior information by newly obtained measurements which may be conducted by Bayesian approach. Updating of probabilistic distributions of basic variables or direct updating of failure probability can be effectively used. Application of theoretical principles is illustrated by a case study of a historic factory built in 1900s. The paper is a tribute to Ton Vrouwenvelder for his essential contributions to developments of theory and promotion of practical applications of probabilistic assessment of existing structures.}, language = {en} }