@inproceedings{SykoraHolickyRozsasetal., author = {S{\´y}kora, Miroslav and Holick{\´y}, Milan and R{\´o}zs{\´a}s, {\´A}rp{\´a}d and Barnardo-Viljoen, Celeste and Retief, Johan Verster and Diamantidis, Dimitris}, title = {Risk Based Design of Infrastructures under Extreme Actions due to Environmental Change}, series = {Life-cycle of engineering systems: emphasis on sustainable civil infrastructure, Symposium of the International Association for Life-Cycle Civil Engineering (IALCCE), 2016, Delft}, booktitle = {Life-cycle of engineering systems: emphasis on sustainable civil infrastructure, Symposium of the International Association for Life-Cycle Civil Engineering (IALCCE), 2016, Delft}, publisher = {Taylor \& Francis}, abstract = {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.}, language = {en} } @inproceedings{SykoraDiamantidisHolickyetal., author = {S{\´y}kora, Miroslav and Diamantidis, Dimitris and Holick{\´y}, Milan and Markova, Jana and Charters Morais, Eduardo}, title = {Compressive Strength of Historic Masonry based on Destructive and Non-Destructive Test Results}, series = {Proceedings of the 3rd International Conference on Protection of Historical Constructions (PROHITECH'17), July 12-15, 2017, Lisbon, Portugal}, booktitle = {Proceedings of the 3rd International Conference on Protection of Historical Constructions (PROHITECH'17), July 12-15, 2017, Lisbon, Portugal}, language = {en} } @incollection{SykoraDiamantidisHolickyetal., author = {S{\´y}kora, Miroslav and Diamantidis, Dimitris and Holick{\´y}, Milan and Jung, Karel}, title = {Target reliability for new and existing railway civil engineering structures}, series = {Handbook of RAMS in Railway Systems : theory and practice}, booktitle = {Handbook of RAMS in Railway Systems : theory and practice}, publisher = {CRC Press}, isbn = {9781315269351}, doi = {10.1201/b21983-20}, pages = {26}, abstract = {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.}, language = {en} } @article{DiamantidisHolickySykora, author = {Diamantidis, Dimitris and Holicky, Milan and S{\´y}kora, Miroslav}, title = {Reliability and Risk Acceptance Criteria for Civil Engineering Structures}, series = {Transactions of the VSB - Technical University of Ostrava, Civil Engineering Series}, volume = {16}, journal = {Transactions of the VSB - Technical University of Ostrava, Civil Engineering Series}, number = {2}, publisher = {De Gruyter}, pages = {1 -- 10}, abstract = {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.}, language = {en} } @book{HolickyDiamantidisSykoraetal., author = {Holick{\´y}, Milan and Diamantidis, Dimitris and S{\´y}kora, Miroslav and Markov{\´a}, Jana and Vrouwenfelder, Ton and Tanner, Peter and Arteaga, Angel and Lara Sarache, Carlos and Croce, Pietro and Toprak, Selcuk and Senel, Sevket Murat and Inel, Mehmet}, title = {Methods for the risk assessment and risk-based management of aging infrastructure}, publisher = {Czech Technical University in Prague, Klokner Institute}, address = {Prague}, isbn = {978-80-01-05611-0}, abstract = {The Leonardo da Vinci Project, "Innovation Transfer in Risk Assessment and Management of Aging Infrastructures", CZ/13/LLP-LdV/TOI/134014, addresses the urgent need to train students, young engineers and professionals in the assessment of existing infrastructures. The future of the construction industry lies in moving from new constructions towards the maintenance, repair and rehabilitation of existing structures, particularly of aging infrastructures. Risk management consisting of risk assessment and risk control of existing structure therefore plays thereby an important role. The assessment of existing infrastructures is an imperative issue of great economic significance in most countries around the world, as more than 50 \% of all construction activities concerns existing buildings, bridges and other civil engineering works. At present, the Eurocodes which will be used in all CEN Member countries are primarily focused on the design of new structures. Additional operational rules for existing structures are still missing. The international standard ISO 13822 provides only general principles for the assessment of existing structures which should be further developed for their effective operational use in practice. The overall procedure of risk management of aging infrastructures is therefore an urgent issue of great economic significance in most countries around the world. This is primarily caused due to the fact that many infrastructures are affected by action effects, fatigue and environmental influences, and inevitably deteriorate. Moreover, available resources for the maintenance, repair or possible replacement of infrastructures are always limited. Typical questions and problems which must be solved in this context can be summarized as follows: • What is the current state of a particular infrastructure? • What is an acceptable level of the relevant risk? • Which aspects are critical to sustainable performance? • What is the optimum life-cycle cost? • What is the best long-term funding strategy? The proposed project highlights the above problems and focusses also on vocational training in risk management and assessment of aging infrastructure in the partner countries (CZ, DE, ES, IT and TR). The current project addresses the urgent need for practical implementation of principles of the management and risk assessment of existing infrastructures in all the partner countries. The project is supported by the Czech Chamber of Chartered Engineers (ČKAIT). The project consortium, under the leadership of the Klokner Institute of the Czech Technical University in Prague (KI CTU), consists of five other partners, including research institutions and universities from three EU Member States (DE, ES, IT) as well as one associated country (TR), and also the Secondary Technical School of Civil Engineering in Ceske Budejovice (CZ). All researchers within the partnership are involved in research projects dealing with reliability assessment of existing structures. They participate in the national and international standardization activities within the international organizations CEN (European Committee for Standardisation) and ISO (International Standardization Organisation). The project outcomes consist of vocational training materials based on international research and relevant standard committee's activities, and on the significant experience gained from case studies, and on selected results obtained from the previous projects of the Leonardo da Vinci programme. In particular, the experience gained by the partners of the present consortium from the completed project on vocational training related to assessment of existing structures is utilized. Available innovations are transferred to undergraduate and graduate students, practising engineers and local government representatives. The developed training materials are of practical use in offering illustrative examples and several case studies. All the project outcomes are based on documents of the international research organization, Joint Committee on Structural Safety JCSS and international research projects, selected outcomes of the previous project of the Leonardo da Vinci programme (developed by five partners of the present consortium in 2013-2015) and also on background documents to the new European and international standards. Particular outcomes of the proposed project include practical handbooks, software tools, web-sites, e-learning, courses and seminars organized in the partners´ home countries. The project outcomes will also be offered to other European countries through code committees work, lectures and the project web-sites. It is foreseen that the outcomes being used by engineers, designers, technicians, and representatives of public authorities involved in planning and management will have an impact on the risk-based management of infrastructures. One of the important project outcomes is the present Handbook 1 "Methods for the Risk Assessment and Risk-Based Management of Aging Infrastructure", which is focussed on general procedures of risk-management and assessment of aging infrastructures. The methodologies provided are independent of the type of structure and material, and are compatible with the background methodologies used in the Eurocodes. Operational techniques for the assessment of aging infrastructures supplemented by illustrative case studies are presented in Handbook 2 and Handbook 3, which also result from the mentioned project. Handbook 1 consists of ten chapters and one annex. Chapter 1 gives a brief overview of the basic concepts used in the management and risk assessment of existing structures, supplemented by the basic definitions and terminology. Chapter 2 summarizes current applicable standards, codes and recommendations related to actions and environmental influences on existing structures. Chapter 3 reviews the most important degradation models due to environmental influences. Fatigue effects are treated separately in Chapter 4. The following Chapters, 5, 6, 7 and 8, are devoted step by step to the entire procedure of risk management, including probabilistic reliability analysis, consequence analysis, risk evaluation and risk assessment based on risk acceptance criteria, and consequently provide important information supporting decisions concerning the safety of the structure. The last two Chapters, 9 and 10, illustrate instructive case studies concerning risk management and risk assessment of road tunnels. Annex A presents basic statistical methods and techniques used in the evaluation and updating of available data required for probability and consequence analysis. It is believed that the material of this handbook is presented in an understandable way, illustrated by several realistic examples. A number of references mentioned in each chapter provide additional background materials, further guidance and information useful for particular practical applications. Prague and Regensburg, 2014}, language = {en} } @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} } @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{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{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} }