Earthquakes and Structures

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Should accidental eccentricity be eliminated from Eurocode 8?

  • Anagnostopoulos, S.A. (Department of Civil Engineering University of Patras) ;
  • Kyrkos, M.T. (Attica Region) ;
  • Papalymperi, A. (University of Patras) ;
  • Plevri, E. (University of Patras)
  • Received : 2014.06.13
  • Accepted : 2014.09.19
  • Published : 2015.02.25
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Abstract

Modern codes for earthquake resistant building design require consideration of the so-called accidental design eccentricity, to account for torsional response caused by several factors not explicitly considered in design. This provision requires that the mass centres in the building floor be moved a certain percentage of the building's dimension (usually 5%) along both the x and y axes and in both positive and negative directions. If one considers also the spatial combinations of the two component motion in a dynamic analysis of the building, the number of required analyses and combinations increases substantially, causing a corresponding work load increase for practicing structural engineers. Another shortcoming of this code provision is that its introduction has been based primarily on elastic results from investigations of oversimplified, hence questionable, one story building models. This problem is addressed in the present paper using four groups of eccentric braced steel buildings, designed in accordance with Eurocodes 3 (steel) and 8 (earthquake design), with and without accidental eccentricities considered. The results indicate that although accidental design eccentricities can lead to somewhat reduced inelastic response demands, the benefit is not significant from a practical point of view. This leads to suggestions that accidental design eccentricities should probably be abolished or perhaps replaced by a simpler and more effective design provision, at least for torsionally stiff buildings that constitute the vast majority of buildings encountered in practice.

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References

  1. Anagnostopoulos, S.A. (1981), "Inelastic beams for seismic analyses of structures", J. Struct. Div., ASCE, 107(7), 1297-1311.
  2. Anagnostopoulos, S.A., Kyrkos, M.T. and Stathopoulos, K.G. (2013), "Earthquake induced torsion in buildings: critical review and state of the art", Plenary Keynote Lecture, ASEM.
  3. Anagnostopoulos, S.A., Kyrkos, M.T. and Stathopoulos, K.G. (2015), "Earthquake induced torsion in buildings: Critical review and State of the Art updated", Earthq. Struct., Special Volume on Torsion.
  4. Aviles, J. and Suarez, M. (2006), "Natural and accidental torsion in one-storey structures on elastic foundation under non-vertically incident SH-waves", Earthq. Eng. Struct. Dyn., 35, 829-850. https://doi.org/10.1002/eqe.558
  5. Carr A.J. (2005), Ruaumoko Manual, Volume 3, User manual for the 3-dimensional Version- Ruaumoko 3D.
  6. Chandler, A.M., Correnza, J.C. and Hutchinson, G.L. (1995), "Influence of accidental eccentricity on inelastic seismic torsional effects in buildings", Eng. Struct., 17(3), 167-178. https://doi.org/10.1016/0141-0296(94)00003-C
  7. DeBock, D.J, Liel, A.B., Haselton, C.B., Hooper, J.D. and Henige Jr., R.A. (2014), "Import- ance of seismic design accidental torsion requirements for building collapse capacity", Earthq. Eng. Struct. Dyn., 43(6), 831-850. https://doi.org/10.1002/eqe.2375
  8. De La Colina, J. and Almeida, C. (2004), "Probabilistic study on accidental torsion of low-rise buildings", Earthq. Spectra, 20(1), 25-41. https://doi.org/10.1193/1.1646391
  9. De La Colina, J., Benitez, B. and Ruiz, S.E. (2011), "Accidental eccentricity of story shear for low-rise office buildings", J. Struct. Eng., 137, 513-520. https://doi.org/10.1061/(ASCE)ST.1943-541X.0000302
  10. De La Llera, J.C. and Chopra, A.K. (1992), "Evaluation of code accidental torsion provisions using earthquake records from three nominally symmetric-plan buildings", EERC Report No. UCB/EERC-92/09, University of California, Berkeley, California, US.
  11. De La Llera, J.C. and Chopra, A.K. (1994a), "Evaluation of code accidental-torsion provisions from building records", J. Struct. Eng., 120(2), 597-616. https://doi.org/10.1061/(ASCE)0733-9445(1994)120:2(597)
  12. De La Llera, J.C. and Chopra, A.K. (1994b), "Accidental torsion in buildings due to stiffness uncertainty", Earthq. Eng. Struct. Dyn., 23(2), 117-136. https://doi.org/10.1002/eqe.4290230202
  13. De La Llera, J.C. and Chopra, A.K. (1994c), "Using accidental eccentricity in code-specified static and dynamic analyses of buildings", Earthq. Eng. Struct. Dyn., 23(9), 947-967. https://doi.org/10.1002/eqe.4290230903
  14. De La Llera, J.C. and Chopra, A.K. (1995), "Estimation of accidental torsion effects for seismic design of building", J. Struct. Eng., 121(1), 102-114. https://doi.org/10.1061/(ASCE)0733-9445(1995)121:1(102)
  15. Dimova, S.L. and Alashki, I. (2003), "Seismic design of symmetric structures for accidental torsion", Bul. Earthq. Eng., 1, 303-320. https://doi.org/10.1023/A:1026353312676
  16. Karabalis, D.L., Cokkinides G.J., Rizos D.C., Mulliken J.S. and Chen R. (1994), "An interactive computer code for generation of artificial earthquake records", Ed. Khozeimeh, K., Computing in Civil Engineering, ASCE, New York.
  17. Kyrkos, M.T. and Anagnostopoulos, S.A. (2011a), "An assessment of code designed, torsionally stiff, asymmetric steel buildings under strong earthquake excitations", Earthq. Struct., 2(2),109-126. https://doi.org/10.12989/eas.2011.2.2.109
  18. Kyrkos, M.T. and Anagnostopoulos, S.A. (2011b), "Improved earthquake resistant design of torsionally stiff asymmetric steel buildings", Earthq. Struct., 2(2), 127-148. https://doi.org/10.12989/eas.2011.2.2.127
  19. Kyrkos, M.T. and Anagnostopoulos, S.A. (2012), "Improved earthquake resistant design of eccentric steel buildings", Soil Dyn. Earthq. Eng., 47, 144-156.
  20. Ramadan, O.M.O., Mehanny, S.S.F. and Mostafa, A. (2008), "Revisiting the 5% accidental eccentricity provision in seismic design codes for multi-story buildings", Proceedings of the 14th World Conference Earthquake Engineering.
  21. Stathopoulos, K.G. and Anagnostopoulos, S.A. (2005), "Inelastic torsion of multistory buildings under earthquake excitations", Earthq. Eng. Struct. Dyn., 34, 1449-1465. https://doi.org/10.1002/eqe.486
  22. Stathopoulos, K.G. and Anagnostopoulos, S.A. (2005), "Effects of accidental design eccentricity on the inelastic earthquake response of asymmetric buildings", Proceedings of the 4th European Workshop on the "Seismic Behaviour of Irregular and Complex Sructures", Thessaloniki, Greece.
  23. Stathopoulos, K.G. and Anagnostopoulos, S.A. (2006), "Importance of accidental design eccentricity for the inelastic earthquake response of buildings", Proceedings of the 13th European Conference Earthquake Engineering.
  24. Stathopoulos, K.G. and Anagnostopoulos, S.A. (2010), "Accidental design eccentricity: Is it important for the inelastic response of buildings to strong earthquakes?", Soil Dyn. Earthq. Eng., 30, 782-797. https://doi.org/10.1016/j.soildyn.2009.12.018
  25. Wong, C.M and Tso, W.K. (1994), "Inelastic seismic response of torsionally unbalanced systems designed under elastic dynamic analysis", Earthq. Eng. Stuct. Dyn., 23(7),777-798. https://doi.org/10.1002/eqe.4290230707

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