Journal Title : International Journal of Modern Trends in Engineering and Science

Author’s Name : P Sudharasanamurthy | B Balachandran  unnamed

Volume 03 Issue 09 2016

ISSN no:  2348-3121

Page no: 63-68

Abstract – This paper is concerned with the effects of various vertical irregularities on the seismic response of a structure. The objective of the project is to carry out Response spectrum analysis (RSA) and Time history Analysis (THA) of vertically irregular RC building frames and to carry out the ductility based design using IS 13920 corresponding to Equivalent static analysis and Time history analysis. Comparison of the results of analysis and design of irregular structures with regular structure was done. The scope of the project also includes the evaluation of response of structures subjected to high, low and intermediate frequency content earthquakes using Time history analysis. Tall structures were found to have low natural frequency hence their response was found to be maximum in a low frequency earthquake. It is because low natural frequency of tall structures subjected to low frequency earthquake leads to resonance resulting in larger displacements. If a high rise structure (low natural frequency) is subjected to high frequency ground motion then it results in small displacements. Similarly, if a low rise structure (high natural frequency) is subjected to high frequency ground motion it results in larger displacements whereas small displacements occur when the high rise structure is subjected to low frequency ground motion. 

Keywords— Vertically irregular RC building frame, Response spectrum analysis, Equivalent static analysis, Time history analysis


  1. Valmundsson and Nau, 1997, Seismic Response of Building Frames with Vertical Structural Irregularities, Journal of structural engineering, 123:30-41.
  2. Anibal G Costa, Carlos S. Oliviera, Ricardo T Duartze,1998, Influence of Vertical Irregularities on Response of Buildings.
  3. Lee Han Seon ,Dong Woo Kee, 2007, Seismic response characteristics of high-rise RC wall buildings having different irregularities in lower stories, Engineering Structures 29 (2007):3149–3167
  4. Sadjadi R, Kianoush M.R. , Talebi S , 2007, Seismic performance of reinforced concrete moment resisting frames, Engineering Structures 29 (2007):2365–2380
  5. Athanassiadou C.J, 2008, Seismic performance of R/C plane frames irregular in elevation, Engineering Structures 30 (2008):1250–1261
  6. Karavallis, Bazeos and Beskos, 2008, Estimation of seismic inelastic deformation demands in plane steel MRF with vertical mass irregularities, Engineering Structures 30 (2008) 3265–3275.
  7. Sarkar P, Prasad A Meher, Menon Devdas, 2010, Vertical geometric irregularity in stepped building frames, Engineering Structures 32 (2010) 2175–2182
  8. Poonam, Kumar Anil and Gupta Ashok K, 2012, Study of Response of Structural Irregular Building Frames to Seismic Excitations, International Journal of Civil, Structural, Environmental and Infrastructure Engineering Research and Development (IJCSEIERD), ISSN 2249-6866 Vol.2, Issue 2 (2012) 25-31
  9. Ravikumar C M, Babu Narayan K S, Sujith B V, Venkat Reddy D, 2012, Effect of Irregular Configurations on Seismic Vulnerability of RC Buildings, Architecture Research 2012, 2(3): 20-26 DOI: 10.5923/j.arch.20120203.01
  10. Haijuan Duana, Mary Beth D. Hueste, 2012, Seismic performance of a reinforced concrete frame building in China, Engineering Structures 41 (2012):77–89
  11. Shahrooz Bahrain M. and Moehle Jack P., Seismic Response And Design ofSetback Buildings- Journal of Structural Engineering, Vol. 116, No. 5, May, 1990 1423-1439
  12. Agarwal Pankaj and Shrikhande Manish- Earthquake resistant design of structures: New Delhi, PHI Learning Private Limited, 2010.
  13. IS 13920-Ductility Design
  14. IS 1893- Calculation of Seismic forces.
  15. IS 456-2000-Design of RC structures.
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