@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{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{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} }