Earthquakes and Structures

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Using an appropriate rotation-based criterion to account for torsional irregularity in reinforced concrete buildings

  • Akshara S P (Department of Civil Engineering, National Institute of Technology Calicut) ;
  • M Abdul Akbar (Department of Civil Engineering, National Institute of Technology Calicut) ;
  • T M Madhavan Pillai (Department of Civil Engineering, National Institute of Technology Calicut) ;
  • Rakesh Pasunuti (L&T Construction) ;
  • Renil Sabhadiya (KEC International, RPG centre)
  • Received : 2023.07.10
  • Accepted : 2024.03.19
  • Published : 2024.05.25
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Abstract

Excessive torsional behaviour is one of the major reasons for failure of buildings, as inferred from past earthquakes. Numerous seismic codes across the world specify a displacement-based or drift-based criterion for classifying buildings as torsionally irregular. In recent years, quite a few researchers have pointed out some of the inherent deficiencies associated with the current codal guidelines on torsional irregularity. This short communication paper aims to envisage the need for a revision of the displacement-based guidelines on torsional irregularity, and further highlight the appropriateness of a rotation-based criterion. A set of 6 reinforced concrete building models with asymmetric shear walls are analysed using ETABS v18.0.2, by varying the number of stories from 1 to 9, and the torsional irregularity coefficient of various stories is calculated using the displacement-based formula. Since rotation about the vertical axis is a direct indication of the twist experienced by a building, the calculated torsional irregularity coefficients of all stories are compared with the corresponding floor rotations. The conflicting results obtained for the torsional irregularity coefficients are projected through five categories, namely mismatch with floor rotations, inconsistency in trend, lack of clarity in incorporation of negative values, sensitivity to low values of displacement and error conceived in the mathematical formulation. The findings indicate that the irregularity coefficient does not accurately represent the torsional behaviour of buildings in a realistic sense. The Indian seismic code-based values of 1.2 and 1.4, which are used to characterize buildings as torsionally irregular are observed to be highly sensitive to the numerical values of displacements, rather than the actual degree of rotation. The study thus emphasizes the revision of current guidelines based on a more relevant rotation-based or eccentricity-based approach.

Keywords

Acknowledgement

The stipend provided to the first author by the Ministry of Education, Government of India for pursuing full-time Ph.D. is gratefully acknowledged.

References

  1. Abdel Raheem, S.E., Ahmed, M.M.M., Ahmed., M.M. and Abdelshafi, A.G.A. (2018), "Evaluation of plan configuration irregularity effects on seismic response demands of L-shaped MRF buildings", Bull. Earthq. Eng., 16(9), 3845-3869. https://doi.org/10.1007/s10518-018-0319-7. 
  2. Abegaz, R.A., Kim, I.H. and Lee, H.S. (2022), "Predicting the seismic behavior of torsionally-unbalanced RC building using resistance eccentricity", Struct. Eng. Mech., 83(1), 1-17. https://doi.org/10.12989/sem.2022.83.1.001. 
  3. Ahmed, M.M.M., Abdo, M.A.B. and Mohamed, W.A.E. (2021), "Vertical geometric irregularity effect on performance-based seismic design for moderate rise RC moment resisting frame buildings", Arab. J. Sci. Eng., 47(10), 12333-12348. https://doi.org/10.1007/s13369-021-06376-y. 
  4. Alaa, K.M., El-Kashif, K.F. and Salem, H.M. (2022), "New definition for torsional irregularity based on floors rotations of reinforced concrete buildings", J. Eng. Appl. Sci., 69(12), 1-35. https://doi.org/10.1186/s44147-021-00061-5. 
  5. Alecci, V., De Stefano, M., Galassi, S., Lapi, M. and Orlando, M. (2019), "Evaluation of the American approach for detecting plan irregularity", Adv. Civil Eng., 2019, 1. https://doi.org/10.1155/2019/2861093. 
  6. Aliakbari, F., Garivani, S. and Shahmari, A. (2020), "Determination of torsional irregularity in response spectrum analysis of building structures", Struct. Eng. Mech., 74(5), 699-709. https://doi.org/10.12989/sem.2020.74.5.699. 
  7. Anagnostopoulos, S.A., Alexopoulou, C. and Stathopoulos, K.G. (2010), "An answer to an important controversy and the need for caution when using simple models to predict inelastic earthquake response of buildings with torsion", Earthq. Eng. Struct. Dyn., 39(5), 521-540. https://doi.org/10.1002/eqe.957. 
  8. Anagnostopoulos, S.A., Kyrkos, M.T. and Stathopoulos, K.G. (2015), "Earthquake induced torsion in buildings: critical review and state of the art", Earthq. Struct., 8(2), 305-377. https://doi.org/10.12989/eas.2015.8.2.305. 
  9. Archana, A.R. and Akbar, M.A. (2021), "Structural irregularity quantification in buildings using vital signs", Struct., 34, 2592-2599. https://doi.org/10.1016/j.istruc.2021.09.026. 
  10. Archana, A.R. and Akbar, M.A. (2022), "A comparative study on structural irregularity of open-office buildings", Asian J. Civil Eng., 23(4), 501-514. https://doi.org/10.1007/s42107-022-00438-8. 
  11. ASCE/SEI 7 (2005), Minimum Design Loads and Associated Criteria for Buildings and Other Structures, American Society of Civil Engineers, Reston, VA, USA. 
  12. ASCE/SEI 7 (2010), Minimum Design Loads and Associated Criteria for Buildings and Other Structures, American Society of Civil Engineers, Reston, VA, USA. 
  13. ASCE/SEI 7 (2016), Minimum Design Loads and Associated Criteria for Buildings and Other Structures, American Society of Civil Engineers, Reston, VA, USA. 
  14. Astudillo, B., Flores, F., Pozo, S. and Charney, F. (2020), "An evaluation of the current approaches and recommendations for more rational approaches for assessing the seismic torsional stability of buildings", EURODYN 2020 XI International Conference on Structural Dynamics, Athens, Greece, November. 
  15. Athanatopoulou, A.M. and Manouka, G.E. (2021), "Torsional sensitivity criteria in seismic codes", Earthq. Struct., 21(1), 1-10. https://doi.org/10.12989/eas.2021.21.1.001. 
  16. Basone, F., Castaldo, P., Cavaleri, L. and Trapani., F.D. (2019), "Response spectrum analysis of frame structures: reliabilitybased comparison between complete quadratic combination and damping-adjusted combination", Bull. Earthq. Eng., 17(5), 2687-2713. https://doi.org/10.1007/s10518-019-00559-7. 
  17. Bhasker, R. and Menon, A. (2020), "Torsional irregularity indices for the seismic demand assessment of RC moment resisting frame buildings", Struct., 26, 888-900. https://doi.org/10.1016/j.istruc.2020.05.018. 
  18. BNBC (2017), Bangladesh National Building Code-Part 6: Structural Design, Housing and Building Research Institute, Dhaka, Bangladesh. 
  19. Bosco, M., Ferrara, G.A.F., Ghersi, A., Marino, E.M. and Rossi, P.P. (2015), "Seismic assessment of existing R.C. framed structures with in-plan irregularity by nonlinear static methods", Earthq. Struct., 8(2), 401-422. https://doi.org/10.12989/eas.2015.8.2.401. 
  20. BS EN 1998-1 (2004), Eurocode 8: Design of Structures for Earthquake Resistance-part 1: general rules, seismic actions and rules for buildings, European Committee for Standardization, Brussels, Belgium. 
  21. Chopra, A.K. and Goel, R.K. (1991), "Evaluation of torsional provisions in seismic codes", J. Struct. Eng., 117(12), 3762-3782. https://doi.org/10.1061/(asce)0733-9445(1991)117:12(3762). 
  22. Chunyu, T., Junjin, L., Hong, Z. and Jinzhe, C. (2012), "Experimental study on seismic behavior of an irregular highrise building", 15th World Conference on Earthquake Engineering, Lisboa, Portugal, September. 
  23. EAK (2003), Greek code for Seismic Resistant Structures, Earthquake Planning and Protection Organization, Athens, Greece. 
  24. Er Akan, A., Bingol, K., O rmecioglu, H.T., Er, A. and O rmecioglu, T.O. (2023), "Towards an earthquake-resistant architectural design with the image classification method", J. Asian Archit. Build. Eng., 23(1), 157-170. https://doi.org/10.1080/13467581.2023.2213299. 
  25. Esteva, L. (1987), "Earthquake engineering research and practice in Mexico after the 1985 earthquakes", Bull. N.Z. Nat. Soc. Earthq. Eng., 20(3), 159-200. https://doi.org/10.5459/bnzsee.20.3.159-200. 
  26. FEMA P-2082-1 (2020), NEHRP Recommended Seismic Provisions for New Buildings and Other Structures-Volume 1, Building Seismic Safety Council of the National Institute of Building Sciences, Washington, D.C., USA. 
  27. Firoj, M. and Singh, S.K. (2018), "Response spectrum analysis for irregular multi-storey structure in seismic zone V", 16th Symposium on Earthquake Engineering, Roorkee, India, December. 
  28. GB 50011 (2010), Code for Seismic Design of Buildings, Ministry of Housing and Urban-Rural Development of the People's Republic of China, Beijing, China. 
  29. Georgoussis, G., Tsompanos, A. and Makarios, T. (2015), "Approximate seismic analysis of multi-story buildings with mass and stiffness irregularities", Proc. Eng., 125, 959-966. https://doi.org/10.1016/j.proeng.2015.11.147. 
  30. Ghanem, A., Lee, Y.J. and Moon, D.S. (2024), "Seismic vulnerability of reinforced concrete frame structures: obtaining plan or vertical mass irregularity from structure use change", J. Struct. Eng., 150(3), 1-13. https://doi.org/10.1061/jsendh.steng12440. 
  31. Goel, R.K. and Chopra, A.K. (1991), "Effects of plan asymmetry in inelastic seismic response of one-story systems", J. Struct. Eng., 117(5), 1492-1513. https://doi.org/10.1061/(ASCE)0733-9445(1991)117:5(1492). 
  32. Gokdemir, H., Ozbasaran, H., Dogan, M., Unluoglu, E. and Albayrak, U. (2013), "Effects of torsional irregularity to structures during earthquakes", Eng. Fail. Anal., 35, 713-717. https://doi.org/10.1016/j.engfailanal.2013.06.028. 
  33. Habibi, A., Gholami, R. and Izadpanah, M. (2019), "Behavior factor of vertically irregular RCMRFs based on incremental dynamic analysis", Earthq. Struct., 16(6), 655-664. https://doi.org/10.12989/eas.2019.16.6.655. 
  34. Haque, M., Ray, S., Chakraborty, A., Elias, M. and Alam, I. (2016), "Seismic performance analysis of RCC multi-storied buildings with plan irregularity", Am. J. Civil Eng., 4(3), 68-73. https://doi.org/10.11648/j.ajce.20160403.11. 
  35. IS 875 (1987), Indian Standard Code of Practice for Design Loads (Other Than Earthquake) for Buildings and Structures-Part 2: Imposed Loads, Bureau of Indian Standards, New Delhi, India. 
  36. IS 456 (2000), Indian Standard for Plain and Reinforced ConcreteCode of Practice, Bureau of Indian Standards, New Delhi, India. 
  37. IS 1893 (2002), Indian Standard Criteria for Earthquake Resistant Design of Structures-Part 1: General Provisions and Buildings, Bureau of Indian Standards, New Delhi, India. 
  38. IS 1786 (2008), Indian Standard for High Strength Deformed Steel Bars and Wires for Concrete Reinforcement-Specification, Bureau of Indian Standards, New Delhi, India. 
  39. IS 1893 (2016), Indian Standard Criteria for Earthquake Resistant Design of Structures-Part 1: General Provisions and Buildings, Bureau of Indian Standards, New Delhi, India. 
  40. IS 13920 (2016), Ductile Design and Detailing of Reinforced Concrete Structures Subjected to Seismic Forces-Code of Practice, Bureau of Indian Standards, New Delhi, India. 
  41. KBC (2009), Korean Building Code, Ministry of Land, Infrastructure and Transport, Sejong City, Korea. 
  42. Kim, T., Kwon, O.S. and Song, J. (2024), "Deep learning-based response spectrum analysis method for building structures", Earthq. Eng. Struct. Dyn., 2024, 1-18. https://doi.org/10.1002/eqe.4086. 
  43. Mitchell, D., DeVall, R.H., Saatcioglu, M., Simpson, R., Tinawi, R. and Tremblay, R. (1995), "Damage to concrete structures due to the 1994 Northridge earthquake", Can. J. Civil Eng., 22(2), 361-377. https://doi.org/10.1139/l95-047. 
  44. Mouhine, M. and Hilali, E. (2020), "Effect of setback irregularity location on the performance of RC building frames under seismic excitation", Arch. Civil Eng., 66(4), 399-412. https://doi.org/10.24425/ace.2020.135228. 
  45. Mouhine, M. and Hilali, E. (2022a), "Seismic vulnerability assessment of RC buildings with setback irregularity", Ain Shams Eng. J., 13(1), 101486. https://doi.org/10.1016/j.asej.2021.05.001. 
  46. Mouhine, M. and Hilali, E. (2022b), "Seismic vulnerability for irregular reinforced concrete buildings with consideration of site effects", Mater. Today Proc., 58, 1039-1043. https://doi.org/10.1016/j.matpr.2022.01.038. 
  47. Naveen, E.S., Abraham, N.M. and Kumari, S.D.A. (2019), "Analysis of irregular structures under earthquake loads", Proc. Struct. Integr., 14, 806-819. https://doi.org/10.1016/j.prostr.2019.07.059. 
  48. NBC (2020), National Building Code of Canada-Volume 1, National Research Council of Canada, Ottawa, Ontario, Canada. 
  49. NBC 105 (2020), Nepal National Building Code-seismic design of buildings in Nepal, Ministry of Urban Development, Kathmandu, Nepal. 
  50. NEAK (1992), New Hellenic Seismic Code, Earthquake Planning and Protection Organization (EPPO), Athens, Greece. 
  51. NSCP C101 (2010), National Structural Code of the PhilippinesVolume 1: Buildings, Towers and Other Vertical Structures, Association of the Structural Engineers, Quezon City, Philippines. 
  52. NTE E.030 (2003), National Building Code, Technical Standard of Building E.030-Earthquake Resistant Design, Lima, Peru. 
  53. NZS 1170.5 (2004), Structural Design Aids-Part 5-Earthquake Actions, Council of Standards, Wellington, New Zealand. 
  54. Ozhendekci, N. and Polat, Z. (2008), "Torsional irregularity of buildings", 14th World Conference on Earthquake Engineering, Beijing, China, October. 
  55. Ozmen, G. (2002), "Torsional irregularity in symmetric structures", Tech. J. Turkish Chamb. Civil Eng., 13(4), 2789-2801. 
  56. Ozmen, G., Girgin, K. and Durgun, Y. (2014), "Torsional irregularity in multi-story structures", Int. J. Adv. Struct. Eng., 6(4), 121-131. https://doi.org/10.1007/s40091-014-0070-5. 
  57. Rao, A.B., Reddy, P.S. and Shaly, C.M. (2022), "Mode shape modification of irregular design of buildings", Mater. Today Proc., 62(4), 1790-1795. https://doi.org/10.1016/j.matpr.2021.12.374. 
  58. Ravikumar, C.M., Narayan, K.B.S., Sujith, B.V., Venkat Reddy, D. (2012), "Effect of irregular configurations on seismic vulnerability of RC buildings", Archit. Res., 2(3), 20-26. https://doi.org/10.5923/j.arch.20120203.01. 
  59. Rutenberg, A. and Pekau, O.A. (1983), "Earthquake response of asymmetric buildings: A parametric study", 4th Canadian Conference on Earthquake Engineering, Vancouver, Canada, June. 
  60. Saadati, D. and Moghadam, A.S. (2023), "EZRVS: An AI-based web application to significantly enhance seismic rapid visual screening of buildings", J. Earthq. Eng., 28(3), 689-706. https://doi.org/10.1080/13632469.2023.2217944. 
  61. Shamrao, P.V. (2021), "Seismic fragility analysis for torsionally imbalanced shear wall concrete building", J. Inst. Eng. Ser. A, 102(2), 553-563. https://doi.org/10.1007/s40030-021-00527-y. 
  62. SI 413 (1995), Design Provisions for Earthquake Resistance of Structures, The Standards Institution of Israel, Tel Aviv, Israel. 
  63. SSDB (2005), Seismic Design Code for Buildings in Taiwan, Construction and Planning Agency, Ministry of the Interior, Taipei City, Taiwan. 
  64. The Building Standard Law of Japan (2001), The Building Centre of Japan, Tokyo, Japan. 
  65. TSC (2007), Specification for Buildings to be Built in Seismic Zones, Ministry of Public Works and Settlement, Government of Republic of Turkiye, Ankara, Turkiye. 
  66. Tso, W.K. and Meng, V. (1982), "Torsional provisions in building codes", Can. J. Civil Eng., 9(1), 38-46. https://doi.org/10.1139/l82-005. 
  67. UBC (1997), Uniform Building Code-Volume 2: Structural Engineering Design Provisions, International Conference of Building Officials, Lansing, MI, USA. 
  68. Ucar, T. and Merter, O. (2019), "Effect of design spectral shape on inelastic response of RC frames subjected to spectrum matched ground motions", Struct. Eng. Mech., 69(3), 293-306. https://doi.org/10.12989/sem.2019.69.3.293. 
  69. Valmundsson, E.V. and Nau, J.M. (1997), "Seismic response of building frames with vertical structural irregularities", J. Struct. Eng., 123(1), 30-41. https://doi.org/10.1061/(ASCE)0733-9445(1997)123:1(30). 
  70. Vijayanarayanan, A.R., Goswami, R. and Murty, C.V.R. (2017), "Identifying stiffness irregularity in buildings using fundamental lateral mode shape", Earthq. Struct., 12(4), 437-448. https://doi.org/10.12989/eas.2017.12.4.437. 
  71. Wood, S.L., Wight, J.K. and Moehle, J.P. (2002), "The 1985 Chile earthquake observations on earthquake-resistant construction in Vina Del Mar", UILU-ENG-87-2002; National Science Foundation, Alexandria, VA, USA. 
  72. Zhang, C., Alam, Z. and Samali, B. (2016), "Evaluating contradictory relationship between floor rotation and torsional irregularity coefficient under varying orientations of ground motion", Earthq. Struct., 11(6), 1027-1041. https://doi.org/10.12989/eas.2016.11.6.1027.