DOI QR코드

DOI QR Code

Evaluating the reliability of using the deflection amplification factor to estimate design displacements with accidental torsion effects

  • Lin, Jui-Liang (National Center for Research on Earthquake Engineering) ;
  • Wang, Wei-Chun (Department of Civil Engineering, National Taiwan University) ;
  • Tsai, Keh-Chyuan (Department of Civil Engineering, National Taiwan University)
  • Received : 2014.07.13
  • Accepted : 2014.12.23
  • Published : 2015.02.25

Abstract

Some model building codes stipulate that the design displacement of a building can be computed using the elastic static analysis results multiplied by the deflection amplification factor, $C_d$. This approach for estimating the design displacement is essential and appealing in structural engineering practice when nonlinear response history analysis (NRHA) is not required. Furthermore, building codes stipulate the consideration of accidental torsion effects using accidental eccentricity, whether the buildings are symmetric-plan, or asymmetric-plan. In some model building codes, the accidental eccentricity is further amplified by the torsional amplification factor $A_x$ in order to minimize the discrepancy between statically and dynamically estimated responses. Therefore, this warrants exploration of the reliability of statically estimated design displacements in accordance with the building code requirements. This study uses the discrepancy curves as a way of assessing the reliability of the design displacement estimates resulting from the factors $C_d$ and $A_x$. The discrepancy curves show the exceedance probabilities of the differences between the statically estimated design displacements and NRHA results. The discrepancy curves of 3-story, 9-story, and 20-story example buildings are investigated in this study. The example buildings are steel special moment frames with frequency ratios equal to 0.7, 1.0, 1.3, and 1.6, as well as existing eccentricity ratios ranging from 0% to 30%.

Keywords

reliability;deflection amplification factor;accidental torsion effect;torsional amplification factor;seismic responses;nonlinear response history analysis

References

  1. Ang, A.H.S and Tang, W.H. (2007), Probability concepts in engineering: emphasis on applications to civil and environmental engineering, 2nd Edition, Wiley.
  2. ASCE (2010), Minimum Design Loads for Buildings and other Structures. ASCE/SEI 7-10. American society of Civil Engineers (ASCE): Reston, VA.
  3. Chopra, A.K. and Chintanapakdee, C. (2004), "Inelastic deformation ratios for design and evaluation of structures: single-degree-of-freedom bilinear systems", J. Struct. Eng., ASCE, 130(9), 1309-1319. https://doi.org/10.1061/(ASCE)0733-9445(2004)130:9(1309)
  4. DeBock, D.J., Liel, A.B., Haselton, C.B., Hoopper, J.D. and Henige, Jr. R.A. (2013), "Importance of seismic design accidental torsion requirements for building collapse capacity", Earthq. Eng. Struct. D., 43(6), 831-850.
  5. De la Llera, J.C. and Chopra, A.K. (1994), "Evaluation of code accidental-torsion provisions from building records", J. Struct. Eng., ASCE, 120(2), 597-616. https://doi.org/10.1061/(ASCE)0733-9445(1994)120:2(597)
  6. De la Llera, J.C. and Chopra, A.K. (1995), "Estimation of accidental torsion effects for seismic design of buildings", J. Struct. Eng., ASCE, 121(1), 102-114. https://doi.org/10.1061/(ASCE)0733-9445(1995)121:1(102)
  7. 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
  8. Eurocode 8 (2004), Design of Structures for Earthquake Resistance. Part1: General Rules, Seismic Actions and Rules for Buildings. prEN 1998-1:2004(E), Commission of the European Communities, European Committee for Standardization, Brussels.
  9. Fajfar, P. (2000), "A nonlinear analysis method for performance-based seismic design", Earthq. Spectra, 16(3), 573-592. https://doi.org/10.1193/1.1586128
  10. Fajfar, P., Kilar, V., Marusic, D. and Perus, I. (2005), "Torsional effects in the pushover-based seismic analysis of buildings", J. Earthq. Eng., 9, 831-854.
  11. FEMA-355C (2000), State of the art report on systems performance of steel moment frames subject to earthquake ground shaking, prepared by the SAC Joint Venture for the Federal Emergency Management Agency, Washington, DC.
  12. Gupta, B. and Kunnath, S.K. (2000), "Adaptive spectra-based pushover procedure for seismic evaluation of structures", Earthq. Spectra, 16(2), 367-392. https://doi.org/10.1193/1.1586117
  13. Humar, J. and Kumar, P. (2000), "A new look at the torsion design provisions in seismic building codes", Proceedings of the 12th World Conference on Earthquake Engineering, Paper No. 1707, New Zealand Society for Earthquake Engineering, Upper Hut, New Zealand.
  14. Iwan, W.D. (1980), "Estimating inelastic response spectra from elastic spectra", Earthq. Eng. Struct. D., 8, 375-388. https://doi.org/10.1002/eqe.4290080407
  15. Kim, S. and D'Amore, E. (1999), "Pushover analysis procedure in earthquake engineering", Earthq. Spectra, 15(3), 417-434. https://doi.org/10.1193/1.1586051
  16. Krawinkler, H., Lignos, D.G. and Putman, C. (2011), "Prediction of nonlinear response-pushover analysis versus simplified nonlinear response history analysis", Structural Congress, 2228-2239, doi:10.1061/41171(401)193. https://doi.org/10.1061/41171(401)193
  17. Krawinkler, H. and Seneviratna, G.D.P.K. (1998), "Pros and cons of a pushover analysis of seismic performance evaluation", Eng. Struct., 20, 452-464. https://doi.org/10.1016/S0141-0296(97)00092-8
  18. Lin, B.Z., Chuang, M.C. and Tsai, K.C. (2009), "Object-oriented development and application of a nonlinear structural analysis framework", Adv. Eng. Softw., 40, 66-82. https://doi.org/10.1016/j.advengsoft.2008.03.012
  19. Lin, J.L., Tsai, K.C. and Chuang, M.C. (2012), "Understanding the trends in torsional effects in asymmetricplan buildings", Bul. Earthq. Eng., 10, 955-965. https://doi.org/10.1007/s10518-012-9339-x
  20. Miranda, E. (2000), "Inelastic displacement ratios for structures on firm sites", J. Struct. Eng., ASCE, 126(10), 1150-1159. https://doi.org/10.1061/(ASCE)0733-9445(2000)126:10(1150)
  21. Miranda, E. and Ruiz-Garcia, J. (2002), "Evaluation of approximate methods to estimate maximum inelastic displacement demands", Earthq. Eng. Struct. D., 31, 539-560. https://doi.org/10.1002/eqe.143
  22. Ruiz-Garcia, J. and Miranda, E. (2006), "Inelastic displacement ratios for evaluation of structures built on soft soil sites", Earthq. Eng. Struct. D., 35, 679-694. https://doi.org/10.1002/eqe.552
  23. UBC (1994), "Structural Engineering Design Provisions", Uniform Building Code, Vol. 2, International Conference of Building Officials.
  24. UBC (1997), "Structural Engineering Design Provisions", Uniform Building Code, Vol. 2, International Conference of Building Officials.
  25. Veletsos, A.S. and Newmark, N.M. (1960), "Effect of inelastic behavior on the response of simple systems to earthquake motions", Proceedings of the 2nd World Conf. on Earthquake Engineering, Vol. II, Tokyo, 895-912.
  26. Wang, W.C., Lin, J.L. and Tsai, K.C. (2014), Reliability assessment of the torsional amplification factor for accidental torsional moment of buildings subjected to earthquakes. Report No. NCREE-14-013, National Center for Research on Earthquake Engineering, Taipei, Taiwan. (in Chinese)

Cited by

  1. Suitability of using the torsional amplification factor to amplify accidental torsion vol.127, 2016, https://doi.org/10.1016/j.engstruct.2016.08.042