Prospects for Advanced Engineering Design Based on Risk Assessment

Current approaches to the design of structures are based on the concept of target probability of failure. This value is, however, often specified on the basis of comparative studies and past experience only. Moreover, the traditional probabilistic approach cannot properly consider gross errors and accidental situations, both becoming every year more and more frequent causes of failure. The submitted paper shows that it is useful to supplement the probabilistic design procedure by the risk analysis and assessment, which can take into account consequences of all unfavourable events. It is anticipated that in a near future the advanced engineering design would include criteria of acceptable risks in addition to the traditional probabilistic conditions. NOTATION g(x) Performance (limit state) function. Cij Consequences of the events Eij. Ctot Total expected cost. Eij Events. Hi Hazard situation i. H1 Hazard situation under normal conditions. H2 Hazard situation due to fire. P(F/Hi) Probability of failure F given the situation Hi. pF Probability of failure F. pd Target probability of failure. pf Probability P(F|H2) of structural failure during fire. pfi,s Probability of fire start P(H2). pfi,d Conditional probabilities of fire flashover given H2. pfi Probability of fire flashover. pt,fi Target probability of structural failure under fire design situation. x Generic point of the vector of basic variables. X Vector of basic variables. β Reliability index ϕX(x) Probability density function of the vector of basic variables X. ΦX(x) Distribution function of the vector of basic variables X.