The work presented in this paper was developed under
the PhD thesis entitled “Reliability and Cost Models of
Pile Foundations”. Our main goal is to present
guidelines for geotechnical engineers to carry out
reliability based designs (RBD). This analyses help
evaluate the probability of a particular behavior in a
time period, with the knowledge of the input parameters
randomness (uncertainties). The biggest benefit is that it
quantifies and gives information about the parameters
that mostly influence the behavior under study. This
capacity is important, not only because of the new
regulation codes and social concerns, but also because
these probabilistic formats support decision making
under uncertainties, providing qualitative judgments
and investments, very important in geotechnical area.
Based on that, this work shows valuable information
that a geotechnical engineers can obtain from a simple
reliability analysis of a pile foundation, such as the most
influential uncertainties in pile design or the minimum
dimensions of the pile (Figure 3a) and maximum load
(Figure 3b) that lead to a previously established
probability of failure. Furthermore, a comparison
between two widely known RBD methodologies was
done, First Order Reliability Method (FORM) and
Monte Carlo Simulations (MCS). FORM is the most
traditional one, an approximate method (level II of
reliability), while ordinary MCS has a higher level of
accuracy (level III, pure probabilistic) and is a very
straight forward method. Nevertheless, FORM has some
limitations when complex performance functions are
necessary and it is not possible to approximate normal
distributions. The uncertainties considered in this work
and the methodology scheme is presented in Figure 1
(Honjo et al., 2010 and Honjo et al., 2011).FC
