Assessing Structural Health State by Monitoring Peridynamics Parameters in Operational Conditions

This paper aims to analyze the Peridynaimcs (PDs) theory and to exploit it for new possibilities in Civil Engineering by employing the theory for Structural Health Monitoring (SHM). In particular, the paper aims to exploit PDs for SHM and damage characterization of the built environment, at the structural scale, in operational conditions (i.e., without input sources). The reasons behind this study rely on the possibility to use PDs to emulate very complex structural behaviors effortlessly, using PDs as a paradigm to build low fidelity structural models of real systems. In the present paper, new features to characterize the damage (i.e., to detect, locate, and quantify it) are proposed thanks to a special definition of the peridynamic theory written in discrete form. These features are the Bond Extremity Acceleration (BEA) and Bond Extremity Velocity (BEV) conjectures, which are obtained by discretizing a system with the Bond Based PDs and using a micro-viscoelastic constitutive law at the bond level. Moreover, the authors show how the proposed peridynamic parameters are theoretically estimable with very robust techniques already used in SHM, such as the Stochastic Subspace Identification (SSI) algorithms. The considerations reported in the paper are verified with numerical (virtual) models. The paper concludes that PDs can be used to easily parametrize the built environment opening new research possibilities on the use of PDs for civil SHM. Additionally, the proposed BEA proves to be a very scalable and general parameter to be monitored in real systems (providing information on the presence, the location, and the amount of damage), this also due to its physical based meaning and the straightforward method of extraction in operational conditions.