This paper proposes the application of sequential importance sampling (SIS) to the estimation of the
probability of failure in structural reliability. SIS was developed originally in the statistical community
for exploring posterior distributions and estimating normalizing constants in the context of Bayesian
analysis. The basic idea of SIS is to gradually translate samples from the prior distribution to samples
from the posterior distribution through a sequential reweighting operation. In the context of structural
reliability, SIS can be applied to produce samples of an approximately optimal importance sampling density,
which can then be used for estimating the sought probability. The transition of the samples is
defined through the construction of a sequence of intermediate distributions. We present a particular
choice of the intermediate distributions and discuss the properties of the derived algorithm. Moreover,
we introduce two MCMC algorithms for application within the SIS procedure; one that is applicable to
general problems with small to moderate number of random variables and one that is especially efficient
for tackling high-dimensional problems.
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