Abstract :
[en] Structural Health Monitoring with analysis of dynamic characteristics intends to
detect stiffness changes caused by damage. It can be performed by vibrational tests
resulting to modal parameters, that is, eigenfrequencies, damping, modeshapes, or
modal masses. Those parameters are themselves informational and even allow often
deducing the stiffness matrix. Based on that, it is possible to identify and to localize
changes in the stiffness matrix due to damage, that is, localization and quantification
of damage. However, changing test conditions, like ambient temperature or excitation force or existing nonlinearities of concrete, show important influence on damage
indicators and hence need compensation prior to damage detection. Considering this
background, this article focuses on comparing ambient excitation to forced excitation
including appropriate exciters. Furthermore, continuous monitoring is discussed vs
discrete testing in distinct time-intervals. The intention of the comparison is to give
an overview, that is, helpful for choosing appropriate measurement technique for the
sake of correct damage detection subsequently.
