Seismic behavior of isolated bridges with additional damping under far-field and near fault ground motion

  • Losanno, Daniele (Department of Structures for Engineering and Architecture, University Federico II) ;
  • Hadad, Houman A. (Department of Civil Architectural and Environmental Engineering, University of Miami) ;
  • Serino, Giorgio (Department of Structures for Engineering and Architecture, University Federico II)
  • Received : 2016.12.13
  • Accepted : 2017.08.03
  • Published : 2017.08.25


This paper presents a numerical investigation on the seismic behavior of isolated bridges with supplemental viscous damping. Usually very large displacements make seismic isolation an unfeasible solution due to boundary conditions, especially in case of existing bridges or high risk seismic regions. First, a suggested optimal design procedure is introduced, then seismic performance of three real bridges with different isolation systems and damping levels is investigated. Each bridge is studied in four different configurations: simply supported (SSB), isolated with 10% damping (IB), isolated with 30% damping (LRB) and isolated with optimal supplemental damping ratio (IDB). Two of the case studies are investigated under spectrum compatible far-field ground motions, while the third one is subjected to near-fault strong motions. With respect to different design strategies proposed by other authors, results of the analysis demonstrated that an isolated bridge equipped with HDLRBs and a total equivalent damping ratio of 70% represents a very effective design solution. Thanks to confirmed effective performance in terms of base shear mitigation and displacement reduction under both far field and near fault ground motions, as well as for both simply supported and continuous bridges, the suggested control system provides robustness and reliability in terms of seismic performance also resulting cost effective.


seismic response;isolated bridges;optimal design;near-fault;elastomeric bearings;supplemental damping


  1. AASHTO (2010), Guide Specifications for Seismic Isolation Design, Third Edition, American Association State Highway and Transportation Officials, Washington DC, USA.
  2. ANAS (2016), Prezzario ANAS 2016,
  3. Buckle, I. and Monzon, E. (2011), "Seismic isolation design examples of highway bridges", NCHRP 20-7 / Task 262(M2), University of Nevada Reno, 20-7.
  4. Chen, W.F. and Duan, L. (2014), Bridge Engineering Handbook, CRC Press, New York, USA.
  5. Chiou, B., Darragh, R., Gregor, N. and Silva, W. (2008), "NGA project strong-motion database", Earthq. Spectra, 24(1), 23-44.
  6. EC8 (2004), Eurocode 8: Design of structures for earthquake resistance Part 1: General rules, seismic actions and rules for buildings, CEN, European Committee for Standardization.
  7. FIP Industriale (2016),, Selvazzano Dentro(PD), Italy,
  8. Hall, J.F., Heaton, T.H., Halling, M.W. and Wald, D.J. (1995), "Near-source ground motion and its effect on flexible buildings", Earthq. Spectra, 11(4), 569-605.
  9. Iervolino, I., Galasso, C. and Cosenza, E. (2010), "REXEL: computer aided record selection for code-based seismic structural analysis", Bull. Earthq. Eng., 8(2), 399-362.
  10. Jangid, R.S. (2007), "Optimum lead-rubber isolation bearings for near-fault motions", Eng. Struct., 29(10), 2503-2513.
  11. Jangid, R.S. and Kelly, J.M. (2001), "Base isolation for near-fault motions", Earthq. Eng. Struct. D., 30(5), 691-707.
  12. Jonsson, M.H., Bessason, B. and Haflidason, E. (2010), "Earthquake response of a base-isolated bridge subjected to strong near-fault ground motion", Soil Dyn. Earthq. Eng., 30(6), 447-455.
  13. Kelly, J.M. (1997), Earthquake-Resistant Design with Rubber, Springer-Verlag, London.
  14. Kelly, J.M. (1999), "The role of damping in seismic isolation", Earthq. Eng. Struct. D., 28(1), 3-20.<3::AID-EQE801>3.0.CO;2-D
  15. Liao, W.I., Loh C.H. and Lee B.H. (2004), "Comparison of dynamic response of isolated and non-isolated continuous girder bridges subjected to near-fault ground motions", Eng. Struct., 26(14), 2173-2183.
  16. Losanno, D., Spizzuoco, M. and Serino, G. (2014), "Optimal design of the seismic protection system for isolated bridges", Earthq. Struct., 7(6), 969-999.
  17. Makris, N. and Chang, S.P. (2000), "Effect of viscous, viscoplastic and friction damping on the response of seismic isolated structures", Earthq. Eng. Struct. D., 29(1), 85-107.<85::AID-EQE902>3.0.CO;2-N
  18. Martelli, A. and Forni, M. (2010), "Seismic isolation and protection systems", J. Anti-Seism. Syst. Int. Soc., 1(1), 35-55.
  19. Naeim, F. (2000), "Design of seismic isolated structures: From theory to practice", Earthq. Spectra, 16(3), 709-710.
  20. NTC (2008), Nuove norme tecniche per le costruzioni, DM 14 gennaio 2008, Gazzetta Ufficiale n. 29 del 4 febbraio 2008 - Supplemento Ordinario n. 30, Italy.
  21. OpenSees (2016),, University of California, Berkeley, USA.
  22. Ozbulut, O.E. and Hurlebaus, S. (2010), "Optimal design of superelastic-friction base isolators for seismic protection of highway bridges against near-field earthquakes", Earthq. Eng. Struct. D., 40(3), 273-291.
  23. Pantelides, C.P. and Ma, X. (1998), "Linear and nonlinear pounding of structural systems", Comput. Struct., 66(1), 79-92.
  24. Sahasrabudhe, S.S. and Nagarajaiah, S. (2005), "Semi-active control of sliding isolated bridges using MR dampers: an experimental and numerical study", Earthq. Eng. Struct. D., 34(8), 965-983.
  25. Shahi, S.K. and Baker, J.W. (2011), "An empirically calibrated framework for including the effects of near-fault directivity in probabilistic seismic hazard analysis", Bull. Seismol. Soc. Am., 101(2), 742-755.
  26. Shen, J., Tsai, M.H., Chang, K.C. and Lee, G.C. (2004), "Performance of a seismically isolated bridge under near-fault earthquake ground motions", J. Struct. Eng., 130(6), 861-868.
  27. Wang, Y.P., Chung, L.L. and Liao, W.H. (1998), "Seismic response analysis of bridges isolated with friction pendulum bearings", Earthq. Eng. Struct. D., 27(10), 1069-1093.<1069::AID-EQE770>3.0.CO;2-S