Real‐time hybrid simulations including rocking effects: The case of a frame‐structure with unbounded elastomeric isolators

Abstract

Real‐time hybrid simulations (RTHS) have become an attractive alternative for the study of structural systems by conveniently separating an experimental substructure from a numerical component. Due to the technical and economic benefits of applying fiber‐reinforced elastomeric isolators (FREIs) in unbounded configuration, the analysis of this device using RTHS is gaining interest among researchers. However, there are aspects associated with the complexity of the unbounded isolators that alter the dynamic behavior of the structure. One of these aspects is the rocking effect, which generally is disregarded when conducting RTHS. This paper addresses the role of rocking effects in the representation of isolated structures through RTHS. The results of different RTHS architectures show that when rocking is not taken into account, the base displacement and interstory drifts can be underestimated by more than 50%. Results from the RTHS are compared to shaking table tests (STTs) of a mock‐up structure isolated with unbounded FREIs, with a maximum error less than 8% in peak and root‐mean‐square values of displacement and force.

Comprehensive Assessment of the Seismic Performance of an Innovative Hybrid Semiactive and Passive State Control System for a Low‐Degree‐of‐Freedom Structure Using Real‐Time Hybrid Simulation

“…Reference Structure. Te reference structure used, shown in Figure 1, was built at the University of Naples Federico II, Italy, with the objective of performing several seismic shake table tests on this structure to evaluate the seismic performance of base isolation systems [16,17,44,45,[69][70][71]. Tis prototype had a scale factor of 1 : 3 for a total height of 2900 mm and a plan area (X-Y) of 2150 × 2650 mm.…”

“…Losanno et al [17,44] assessed the seismic behavior of U-FREI devices when subjected to bidirectional excitation, while the reference structure was supported by them, and concluded that these devices have signifcant potential in terms of reduction of the seismic vulnerability of the structure and cost-efectiveness of production using lowcost materials. Riascos et al [45] conducted an RTHS using a numerical model of this structure with the aim of verifying the importance of considering the rocking efect in the behavior of U-FREI devices and concluded that considering this efect represents an increase in the isolator and structure displacement; however, it represents a reduction in the fundamental frequency of the structure and a signifcant increase in the isolation capacity. Calabrese et al [70] performed a comparison between the results obtained in a shake table test and the results of an RTHS test, concluding that the RTHS is highly efective in validating the behavior of U-FREI devices supporting these types of structures.…”

“…Te isolators had a total height of 44.0 mm and a diameter of 80.0 mm. Recently, Riascos et al [45] conducted the RTHS tests mentioned in Section 2.1, using the same isolators. In addition, the parameters of the Bouc-Wen model that describe these devices numerically are calculated.…”

“…Pauletta et al [40][41][42] conducted experimental tests to assess the dynamic behavior of U-FREI devices, while Spizzuoco et al [43] and Madera et al [5] conducted similar tests under controlled laboratory conditions. Losanno et al [17,44] implemented U-FREI technology as a base isolation system in a symmetrical 2-DOF steel-concrete structure, a methodology subsequently replicated by Riascos et al [45]. Recently, Losanno et al [46] and Calabrese et al [47] employed U-FREI devices as base isolation systems aimed at reducing seismic vulnerability in unreinforced masonry (URM) buildings.…”

“…Experimental evaluations of base isolation systems as experimental substructures were performed by Lanese et al [60] and Nakata et al [61]. Recently, Riascos et al [45] performed an RTHS test with U-FREI devices, taking the upper structure as a numerical substructure. Furthermore, viscous fuid dampers as experimental substructures have been extensively studied using RTHS [62][63][64][65][66][67].…”