PSI - Issue 44

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Gaspar Auad et al. / Structural Integrity Procedia 00 (2022) 000–000

Gaspar Auad et al. / Procedia Structural Integrity 44 (2023) 1474–1481

1481

5. Conclusions This study presents a physical model for dynamic analysis of structures equipped with variable curvature frictional isolators. This numerical approach allows to include important modeling features such as uplift, lateral and vertical impact behavior, large deformations, − ∆ effects, lateral coupling of the force components, and kinematics constraints, among other phenomena. Although the proposed physical model can be used to model any sliding surface represented by an implicit equation, a particular shape generated by revolving a plane ellipse around a vertical axis is studied. This elliptical surface provides a pendular force that exhibits a variable stiffness. The stiffness of the studied isolators increases smoothly as the articulated slider is laterally displaced. This smooth-hardening behavior is assessed as an alternative to mitigate the adverse effects of internal lateral impacts. The physical model was validated by performing a comparison with a Finite Element Model of the frictional device. Both static and dynamic analyses were conducted in order to validate the lateral behavior of the pendular and frictional force and the lateral impact behavior of the three-dimensional numerical formulation. The results provided by both models were similar, validating the equations suggested to represent the dynamic response of variable curvature bearings. Finally, a comparative study of the dynamic response of a reinforced concrete structure equipped with classical spherical Friction Pendulum System (FPS) bearings and elliptical passive adaptive devices was conducted. Using isolators that exhibit smooth-hardening lateral behavior could be an alternative to mitigate the adverse effects of internal lateral impacts. The increase in stiffness reduces the maximum base displacement demand and the probabilities of observing the internal lateral impact. Consequently, a decrease in the base shear developed in the isolation system is obtained. Since lower seismic forces are transmitted to the superstructure, an important reduction of the maximum inter-story drift response is obtained by using passive adaptive frictional isolators. Acknowledgements This research has been funded by the National Agency for Research and Development (ANID) through the ANID PCHA/Doctorado Nacional/2018-21180434 and the FONDECYT project Nº1201841, the authors are grateful for the support. References Almazán, J. L., & Llera, J. C. D. L. (2003). Physical model for dynamic analysis of structures with FPS isolators. Earthquake engineering & structural dynamics, 32(8), 1157-1184. Auad, G., & Almazán, J. L. (2021). Lateral Impact Resilient double concave Friction Pendulum (LIR-DCFP) bearing: Formulation, parametric study of the slider and three-dimensional numerical example. Engineering Structures, 233, 111892. Chimamphant, S., & Kasai, K. (2016). Comparative response and performance of base‐isolated and fixed‐base structures. Earthquake Engineering & Structural Dynamics, 45(1), 5-27. Lee, H. H. (2018). Finite element simulations with ANSYS Workbench 18. SDC publications. Lu, L. Y., Lee, T. Y., & Yeh, S. W., 2011. Theory and experimental study for sliding isolators with variable curvature. Earthquake engineering & structural dynamics, 40(14), 1609-1627. Pranesh, M., & Sinha, R. (2000). VFPI: an isolation device for aseismic design. Earthquake engineering & structural dynamics, 29(5), 603-627. Shenton III, H. W., & Lin, A. N. (1993). Relative performance of fixed-base and base-isolated concrete frames. Journal of Structural Engineering, 119(10), 2952-2968. Zayas, V. A., Low, S. S., & Mahin, S. A., 1990. A simple pendulum technique for achieving seismic isolation. Earthquake spectra, 6(2), 317-333.