B.1 Introduction B.
Planning of experiments is an issue of high relevance across the different engineering
disciplines. Even though the experiments performed are of different types and under different
conditions the same fundamental principles in regard to the planning of experiments are
broadly valid. In the following chapter a brief summary is given on the main statistical and
probabilistic aspects related to the planning, execution and evaluation of experimental tests.
The summary, even though relating specifically to experiments performed in structural and
materials engineering application may serve as a general guidance for experimental work but
also as check list in connection with the documentation and reporting of test results.
B.2 Modelling of Response Characteristics in Structural Engineering B.
Engineering models for strength and deformation characteristics of structural components and
systems may in principle be formulated at any level of approximation within the range of a
purely scientific mathematical description of the physical phenomena governing the problem
at hand (micro-level) and a purely empirical description based on observations and tests
(macro-level).
In structural engineering the physical modelling is, however, generally performed at an
intermediate level sometimes referred to as the meso-level.
Engineering response models will, therefore, in general be based on a physical understanding
of the problem but due to various simplifications and approximations such models will always
to some extent be empirical. This essentially means that if experimental results of e.g. the
ultimate capacity of a portal steel frame are compared to predictions obtained through a
structural model neglecting the effect of non-linearity then there will be a lack of fit. The lack
of fit introduces a so-called model uncertainty, which is associated with the level of
approximation applied in the formulation of the response model.
B.3 Hypothesis Testing and Planning of Experiments B.
Experimental testing is an important means of establishing models for the response (strength,
deformation, etc.) characteristics of structural components and systems. However, as indicated
in the above it is important that experiments and tests are seen as tool to quantify the adequacy
and precision of models, which may be postulated a-priori to the experiments. Thereby and
only then all the available physical understanding of the problem at hand may be fully utilised
together with the test results to achieve a better understanding and a more precise
quantification of the models postulated to describe these.
A practical procedure for the planning and execution of experiments is illustrated in Figure
A1.
Annex B.2