Modeling Strategies for the Lateral Response of Curved Surface Slider Devices Under Extreme Displacement Demands

Abstract

Base isolation represents one of the most efficient strategy for the reduction of the structural vulnerability of buildings and bridges. Design procedures generally aim to provide the proper period shift, in order to reduce spectral acceleration values and, consequently, the base shear and internal forces. On the other hand, high displacement demands can be achieved, which can be partially limited by providing dissipative capacity through hysteretic behaviors. Although design procedures allow to fairly estimate the design displacement of the adopted devices, extreme seismic event can occur, and displacement higher than the design value can be experienced. Especially for Curved Surface Slider devices, if the displacement demand exceeds a certain geometrical limit, non-negligible damage can occur at the sliding pad, and variations in the force response are consequently noticed. In this work modeling strategies for the computation of the seismic response of base-isolated buildings are presented, by considering extreme earthquake loading conditions. Analytical models are reported for Curved Surface Slider devices, calibrated through the experimental outcomes of tests performed at the Laboratory of EUCENTRE Foundation in Pavia (Italy). In addition, simplified dynamic systems are defined, which allow fast assessments of the global response of a base-isolated structure, even though extreme seismic events are applied. Results have been compared to the response returned by an experimental hybrid simulation, in order to evaluate the accuracy of the presented dynamic systems.

Mechanical model of the over-stroke displacement behaviour for double concave surface slider anti-seismic devices

“…The backbone curve of the force-displacement relationship is shown in Figure 5. Compared with another recent study (Furinghetti et al, 2021b), the analytical formulation of the over-stroke stage of motion and the definition of the domain of application (Eqs 8, 17) are novel to this study.…”

“…The proposed formulation has been compared with a few over-stroke tests described by Furinghetti et al (2021b) in which a DCCSS specimen characterized by an effective radius of curvature of R eff 3080mm, a slider diameter of Φ s 260mm, and a geometric capacity displacement of d c ± 275mm was tested under constant velocity v 2.5 mm/sec and constant vertical load W, which were applied to the test apparatus, as shown in Figure 6. Tested DCCSSs were characterized by three different sliding materials: graded polytetrafluoroethylene (PTFE) filled with carbon fibres (μ 0.05) Figure 6A); ultra low-density polyethylene (μ 0.03) Figure 6B); and virgin PTFE (μ 0.01) Figure 6C).…”