ABSTRACT
The annual maximal accepted probability of structural failure based on limiting individual risk may be expressed according to ISO 2394 (1998) as
pf < 10−6/p(d/f ) (1)
where p(d/f ) is the probability of casualties given a structural failure. The annual maximal probability of structural failure based on limiting the risk with respect to human lives may be expressed as
pf < AN −k (2)
where N is the expected number of fatalities per year. For the constants A and k , the values A = 0, 01 to 0, 1 and k = 1 to 2 are recommended in ISO 2394 (1998). In case that for a specific structure the maximum accepted value N = 5 is specified on the basis of risk analysis, it may be determined from condition (2) that annual maximal accepted failure probability for a structure should be less than pf ,1 < 4 × 10−4 (for fifty years design working life pf ,50 < 2 × 10−2). The reliability index βt,1 = 3, 35 per one year and βt,50 = 2, 05 per fifty years corresponds to these probabilities. It should be noted here that Eurocodes do not give recommendations for the target reliability level in accidental design situations.
