In order to evaluate the effective dynamic behaviour of the structure and to characterise the system, the dynamic load tests are performed. The characterisation could allow to calculate directly the structure’s response to every dynamic action with known features, such as earthquakes or a working dynamic load as well as to refine, according to experimental hits (comparison with benchmarks numerically evaluated), the numeric modelling, developed for the structure analysis. And then, it enables also to identify a proper numeric pattern suitable for the structure representation.
From the experimental point of view, the fluctuations to be analysed are divided into:
- Free fluctuations, caused by transient phenomena (impulses, liberation from compulsory states, distortions etc.)
- Forced fluctuations caused by loads generally known, of no-zero entity periodically variable
- Environmental fluctuations caused by factors, generally non-measurable, related to the environment surrounding the structure (wind, microquakes, induced vibrations etc.)
Using the Fourier analysis, it is possible to identify the numerical model, while subsequent analysis enable to an appropriate evaluation of the stress of the structure’s elements, so that it will be possible to evaluate the handiwork’s actual conditions.