PSI - Issue 78

Alessandro Contento et al. / Procedia Structural Integrity 78 (2026) 1975–1982

1980

use actuators and sensors to adjust the tension in the restraints, modifying the force applied to the elements based on the measured seismic response. Ceravolo et al. (2016, 2017) and Pecorelli and Ceravolo (2018) proposed control strategies based on feedback laws that regulate the tensile force applied by tie rods placed at the corners of rigid blocks. This approach dynamically enhances overturning resistance during critical phases of seismic events, while maintaining low force levels during normal conditions, thereby reducing wear and potential long-term damage. These systems mark an important advancement in seismic protection for NSEs, offering a compromise between effectiveness, durability, and cost, with the potential to significantly improve the safety of vulnerable elements. Beyond isolation and anchorage systems, recent literature has explored innovative solutions based on integrating additional mechanical devices that directly influence the overturning dynamics of freestanding elements. Among the most promising are inertial devices and external resonators. Thiers-Moggia and Málaga-Chuquitaype (2019) studied the use of inerters, mechanical devices that produce a force proportional to the relative acceleration, applied to rigid blocks subjected to seismic excitations. The inerter significantly increases the overturning resistance capacity, improving stability without intrusively altering the structure or support system (Fig. 3).

In parallel, Pan and Málaga-Chuquitaype (2020) proposed the use of non-intrusive external resonators capable of attenuating the seismic response of buildings and historical monuments that are sensitive to uplift and rocking. These devices act as tuned external masses designed to counteract critical vibration frequencies, reducing amplification and the associated risk of damage. These strategies represent promising solutions for the protection of elements with high historical or functional value, effectively integrating traditional methods with advanced technologies to mitigate dynamic response. 5. Limitations of current research and future perspectives 5.1. Current state of research and main gaps In recent decades, the scientific community has made significant progress in studying the seismic response of NSEs dominated by rocking behavior. However, several gaps remain that limit their practical applicability and the generalization of findings. In particular, most research still focuses on idealized or broadly applicable models, often overlooking the complexity and diversity of real-world configurations. A critical issue is the lack of studies that effectively integrate the interaction between NSEs and the primary structure. This interaction can substantially influence the dynamic response, force transmission, and risk of damage. Furthermore, existing methodologies for predicting dynamic and seismic response are still in their early stages in terms of scalability to different configurations and varying seismic conditions. The lack of standardization in modeling approaches and the limited availability of experimental data represent additional obstacles to the widespread adoption and practical implementation of these findings. Fig. 3. Improvement of the seismic overturning capacity of a representative block equipped with inerters, a strategy developed by Thiers-Moggia and Málaga-Chuquitaype (2019). The seismic capacity is expressed in terms of fragility function (P ro a dimensionless velocity-based intensity measure (IM).