Accounting for the aftershock effect in the life-cycle assessment of structures

Most of life-cycle models for earthquake resistant structures consider that damage accumulation and failure are possibly due to subsequent mainshocks. Because there is a chance that also aftershocks worsen structural conditions, it may be appropriate to include this effect in the life-cycle assessment. Recently, stochastic processes for occurrence of aftershocks and their effect on cumulative structural damage have been formalized. These can be employed to develop stochastic damage accumulation models for earthquake resistant structures, accounting for the effect of the whole cluster (i.e., a single mainshoc k - aftershock sequence) . In the paper, a model of such kind is formulated with reference to simple elastic - perfectly - plastic single degree of freedom systems. Temporal distribution of mainshocks is modeled via a homogeneous Poisson process ; temporal distrib ution of aftershocks in a cluster, is modeled by means of a conditional non - homogeneous Poisson process . A n a pproximated closed - form solution is derived for the reliability assessment under the two hypotheses that total damages produced by events pertainin g to different clusters are independent and identically distributed ; the gamma distribution is adopted to represent the distribution of damage in one cluster . An application illustrates the implications of the model on the life - cycle assessment , also in co mparison with the case in which the effect of damaging aftershocks is ignored.