Testing a new procedure for damage detection on framed structures subjected to strong motion earthquakes

Structural Health Monitoring and Damage Detection are areas of current interest in civil, mechanical and aerospace engineering. For many years, experimental modal testing has become a significant topic in the field of structural assessment, not only with regards to typical structures of mechanical engineering, but also of civil engineering. Damage Detection approach based on dynamic monitoring of structural properties over time has received a considerable attention in recent scientific literature. The basic idea arises from the notion that spectral properties, described in terms of the so-called modal parameters (eigenfrequencies, mode shapes, and modal damping), are functions of the physical properties of the structure (mass, energy dissipation mechanisms and stiffness). Structural damage exhibits its main effects in terms of stiffness and damping variation. As a consequence, using a permanent dynamic monitoring system becames possible to detect and, if suitably diffused on the structure, to localize structural and non-structural damage occurred on the structure during a strong earthquake. In this paper a new methodology to detect and localize a possible damage occurred on a framed structure after an earthquake is presented. INTRODUCTION In the most general terms, damage can be defined as changes introduced into a system that adversely affect its current or future performance. Implicit in this definition is the concept that damage is not meaningful without a comparison between two different states of the system, one of which is assumed to represent the initial, and often undamaged, state. This theme issue is focused on the study of damage identification in structural and mechanical systems. Therefore, the definition of damage will be limited to changes to the material and/or geometric properties of these systems, including changes to the boundary conditions and system connectivity, which adversely affect the current or future performance of these systems. The process of implementing a damage identification strategy for aerospace, civil and mechanical engineering infrastructure is referred to as structural health monitoring (SHM). This process involves the observation of a structure or mechanical system over time using periodically spaced measurements, the extraction of damage-sensitive features from these measurements and the statistical analysis of these features to determine the current state of system health. For long-term 1 Postdoctoral Fellow, University of Basilicata, Potenza, Italy, r.ditommaso@unibas.it 2 Associate Professor, University of Basilicata, Potenza, Italy, felice.ponzo@unibas.it 3 Postdoctoral Fellow, University of Basilicata, Potenza, Italy, gianluca.auletta@tiscali.it 4 Master Degree, University of Basilicata, Potenza, Italy, iacovinochiara@libero.it