Commenced in January 2007
Paper Count: 30127
An Advanced Exponential Model for Seismic Isolators Having Hardening or Softening Behavior at Large Displacements
Abstract:In this paper, an advanced Nonlinear Exponential Model (NEM), able to simulate the uniaxial dynamic behavior of seismic isolators having a continuously decreasing tangent stiffness with increasing displacement in the relatively large displacements range and a hardening or softening behavior at large displacements, is presented. The mathematical model is validated by comparing the experimental force-displacement hysteresis loops obtained during cyclic tests, conducted on a helical wire rope isolator and a recycled rubber-fiber reinforced bearing, with those predicted analytically. Good agreement between the experimental and simulated results shows that the proposed model can be an effective numerical tool to predict the force-displacement relationship of seismic isolation devices within the large displacements range. Compared to the widely used Bouc-Wen model, unable to simulate the response of seismic isolators at large displacements, the proposed one allows to avoid the numerical solution of a first order nonlinear ordinary differential equation for each time step of a nonlinear time history analysis, thus reducing the computation effort. Furthermore, the proposed model can simulate the smooth transition of the hysteresis loops from small to large displacements by adopting only one set of five parameters determined from the experimental hysteresis loops having the largest amplitude.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1128863Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 492
 F. Naeim and J. M. Kelly, Design of Seismic Isolated Structures: From Theory to Practice. New York: John Wiley & Sons, 1999.
 M. C. Constantinou, A. S. Whittaker, Y. Kalpakidis, D. M. Fenz and G. P. Warn, “Performance of seismic isolation hardware under service and seismic loading,” Technical Report MCEER-07-0012, State University of New York, Buffalo, 2007.
 M. Spizzuoco, V. Quaglini, A. Calabrese, G. Serino and C. Zambrano, “Study of wire rope devices for improving the re-centering capability of base isolated buildings,” Structural Control and Health Monitoring, to be published.
 C. S. Tsai, T. C. Chiang, B. J. Chen and S. B. Lin, “An advanced analytical model for high damping rubber bearings,” Earthquake Engineering and Structural Dynamics, vol. 32, pp. 1373-1387, 2003.
 N. Vaiana, M. Spizzuoco and G. Serino, “Influence of displacement amplitude and vertical load on the horizontal dynamic and static behavior of helical wire rope isolators,” Proceedings of the 19th International Conference on Earthquake and Structural Engineering, London, United Kingdom, 2017.
 M. Spizzuoco, A. Calabrese and G. Serino, “Innovative low-cost recycled rubber-fiber reinforced isolator: experimental tests and finite element analyses,” Engineering Structures, vol. 76, pp. 99-111, 2014.
 M. C. Constantinou, A. Mokha and A. M. Reinhorn, “Teflon bearings in base isolation II: modeling,” Journal of Structural Engineering, vol. 116, no. 2, pp. 455-474, 1990.
 S. Nagarajaiah, A. M. Reinhorn and M. C. Constantinou, “Nonlinear dynamic analysis of 3-D base-isolated structures,” Journal of Structural Engineering, vol. 117, no. 7, pp. 2035-2054, 1991.
 G. F. Demetriades, M. C. Constantinou and A. M. Reinhorn, “Study of wire rope systems for seismic protection of equipment in buildings,” Engineering Structures, vol. 15, no. 5, pp. 321-334, 1993.
 Y. Q. Ni, J. M. Ko, C. W. Wong and S. Zhan, “Modelling and identification of a wire-cable vibration isolator via a cyclic loading test. Part 1: experiments and model development,” Journal of Systems and Control Engineering, vol. 213, no. I3, pp. 163-171, 1999.
 N. Vaiana, F. C. Filippou and G. Serino, “Nonlinear dynamic analysis of base-isolated structures using a partitioned solution approach and an exponential model,” Proceedings of the 19th International Conference on Earthquake and Structural Engineering, London, United Kingdom, 2017.
 G. Serino, “Modelli per la determinazione delle proprietà meccaniche degli isolatori elastomerici armati,” Convenzione di ricerca con l’ENEL/DSR/CRIS, Rapporto Tecnico fase 1/94, Napoli, 1994.
 R. Bouc, “Modele mathematique d’hysteresis,” Acustica, vol. 24, pp. 16- 25, 1971.
 Y. K. Wen, “Method for random vibration of hysteretic systems,” Journal of the Engineering Mechanics Division, vol. 102, no. EM2, pp 249-263, 1976.
 Y. K. Wen, “Equivalent linearization for hysteretic systems under random excitation,” Journal of Applied Mechanics, vol. 47, pp 150-154, 1980.
 N. Vaiana and G. Serino, “Speeding up nonlinear time history analysis of base-isolated structures using a nonlinear exponential model,” Proceedings of the 19th International Conference on Earthquake Engineering, Barcelona, Spain, 2017.
 S. Pagano, M. Russo, S. Strano and M. Terzo, “A mixed approach for the control of a testing equipment employed for earthquake isolation systems,” Journal of Mechanical Engineering Science, vol. 228, no. 2, pp. 246-261, 2014.