A quarter of the century has elapsed since I gave my first course in
structural reliability to graduate students at the University of
Waterloo in Canada. Since that time on I have given many courses and
seminars to students, researchers, designers, and site engineers
interested in reliability. I also participated in and was responsible
for numerous projects where reliability solutions were required. During
that period, the scope of structural reliability gradually enlarged to
become a substantial part of the general reliability theory. First, it
is apparent that bearing structures should not be isolated objectives of
interest, and, consequently, that constntCted facilities should be
studied. Second, a new engineering branch has emerged -reliability
engineering. These two facts have highlighted new aspects and asked for
new approaches to the theory and applications. I always state in my
lectures that the reliability theory is nothing more than mathematized
engineering judgment. In fact, thanks mainly to probability and
statistics, and also to computers, the empirical knowledge gained by
Humankind's construction experience could have been transposed into a
pattern of logic thinking, able to produce conclusions and to forecast
the behavior of engineering entities. This manner of thinking has
developed into an intricate network linked by certain rules, which, in a
way, can be considered a type of reliability grammar. We can discern
many grammatical concepts in the general structure of the reliability
theory.