PZT-Based Structural Health Monitoring of a Retrofitted RC Frame Structure with Vertical Greenery Systems

Globally, a significant portion of building infrastructure is aging and requires urgent assessment and retrofitting to meet modern provisions and sustainability standards. This issue is particularly critical in seismically active regions, where a significant proportion of existing building stock consists of reinforced concrete (RC) structures that were designed according to outdated seismic codes. At the same time, modern cities are increasingly adopting energy renovation and green retrofit strategies, including vertical forest (VF) renovations. Consequently, there is an extended need for applicable Non-Destructive Testing (NDT) methods to evaluate the severity of damage in RC structures. In this context, Structural Health Monitoring (SHM) techniques could constitute an effective response to these demands to avoid sudden collapses and to support the development of targeted and well-designed plans for repairing and retrofitting strategies, expanding the lifespan of RC structures. Specifically, the Electromechanical Impedance (EMI) method, based on the electromechanical coupling of PZT sensors, has proven to be highly sensitive to changes in the mechanical properties of structural elements. Within this framework, the present study investigates the integration of VF renovation, including structural interventions, with SHM technologies. Therefore, shake table experiments were conducted on an RC frame structure before and after structural strengthening, with PZT installed at key structural locations. The experimental outcomes demonstrate the applicability and the effectiveness of the proposed method in detecting damage in RC frame structures subjected to earthquake excitations.