The goal of this research program is to develop a set of vibration testing procedures suitable for the diagnostic structural assessment of historic masonry buildings, a procedure known as Structural Health Monitoring (SHM). SHM is a global monitoring technique developed to detect damage in a structural system before it reaches a critical stage. Techniques of SHM, as they are used to detect damage, can also be used to assess the improvements in the stiffness of the structure through repair or strengthening campaigns. The basic concept in SHM is that the vibration response of a structure is dependent on the physical properties, such as mass, stiffness, and damping. A change in the structural state of a building alters these properties, which in turn alters in the vibration response. Tools of SHM conveniently assume that the changes in the vibration response, measured through in situ measurements, can be related to the structural state of a building. This assumption makes vibration testing one of the most actively pursued research topics in the fields of SHM.
The biggest obstacle to the successful application of SHM to existing monumental structures is the lack of guidance in making suitable decisions about the following three aspects:
- Selection of optimum excitation source that makes the structure demonstrate the effects of damage in its vibration response.
- Placement of sensors in optimum locations to assure sufficient sensitivity to damage.
- Selection of suitable vibration based features (damage indicator) for symptom-based diagnosis of damage, such as peak response, FRF amplitude, natural frequencies, mode shapes, mode shape curvature, …etc.