Seismic Performance Assessment of Steel Moment Frames with Non-parallel System Irregularity

Document Type : Regular Paper


1 Assistant Professor, Department of Civil & Environmental Engineering, AmirKabir University of Technology (Tehran Polytechnic), Tehran, Iran

2 Former graduate student, Department of Civil & Environmental Engineering, AmirKabir University of Technology (Tehran Polytechnic), Tehran, Iran


Many structures exhibit non-orthogonal systems irregularity based on architectural design, which is a type of torsional irregularity. This paper evaluates the inelastic response of multi-story steel moment resisting frames with this type of irregularity. A parametric study is carried out on six building models exhibiting coupled behavior in lateral and torsional response with various degrees of torsional irregularity. Current code regularity limits for structures appear to be based on engineering judgment rather than on quantitative analyses, which indicates that these limits need to be investigated for different structural systems with different types of irregularities. Another goal of this paper is the evaluation and comparison of the response modification factor values of steel moment resisting frames with non-parallel systems irregularity derived by pushover analysis, as well as nonlinear time history analysis. A new torsional irregularity coefficient is proposed based on the response spectrum analysis results. It is shown that it is essential to undertake nonlinear dynamic analysis to design some structures with high irregularity in plan and to capture nonlinear mechanisms due to non-parallel systems irregularity.


Main Subjects

[1]     Elnashai AS, di Sarno L. Fundamentals of earthquake engineering. Wiley New York; 2008.
[2]     Pierre C, Dowell EH. Localization of vibrations by structural irregularity. Journal of Sound and Vibration 1987;114:549–64.
[3]     Tezcan SS, Alhan C. Parametric analysis of irregular structures under seismic loading according to the new Turkish Earthquake Code. Engineering Structures 2001;23:600–9.
[4]     Chopra AK, Goel RK. Evaluation of torsional provisions in seismic codes. Journal of Structural Engineering 1991;117:3762–82.
[5]     Aziminejad A, Moghadam AS. Performance of asymmetric single story buildings based on different configuration of center of mass, rigidity and resistance. Proceedings of the 4th European workshop on the seismic behaviour of irregular and complex structures, CD ROM. Thessaloniki, 2005.
[6]     Stathopoulos KG, Anagnostopoulos SA. Inelastic earthquake response of single‐story asymmetric buildings: an assessment of simplified shear‐beam models. Earthquake Engineering & Structural Dynamics 2003;32:1813–31.
[7]     Habibi A, Asadi K. Seismic Performance of RC Frames Irregular in Elevation Designed Based on Iranian Seismic Code. Journal of Rehabilitation in Civil Engineering 2013;1:40–55.
[8]     Herrera RG, Soberon CG. Influence of plan irregularity of buildings. The 14th world conference on earthquake engineering, 2008.
[9]     Duan XN, Chandler AM. An optimized procedure for seismic design of torsionally unbalanced structures. Earthquake Engineering & Structural Dynamics 1997;26:737–57.
[10]   Ozmen G. Excessive torsional irregularity in multi-storey structures 2001.
[11]   Demir A, Demir DD, Erdem RT, Bagci M. Torsional irregularity effects of local site classes in multiple storey structures. Int J Res Rev Appl Sci 2010:258–62.
[12]   Penelis GG, Kappos AJ. 3D pushover analysis: The issue of torsion. Proceedings of the 12 th European Conf. on Earthquake Engineering, 2002.
[13]   Jinjie M, Qingxuan S, Qi Z. Method of performance based seismic evaluation for irregular plane reinforced concrete frame structures. 14th World conference on earthquake engineering, Beijing, 2008, p. 12–7.
[14]   Mahdi T, Soltan G v. Plan irregular RC frames: comparison of pushover with nonlinear dynamic analysis. ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING) 2011;12.
[15]   Bosco M, Marino E, Rossi PP. Limits of application of simplified design procedures to non-regularly asymmetric buildings. 13th World conference on earthquake engineering, 2004, p. 1–6.
[16]   Zheng N, Yang Z, Shi C, Chang Z. Analysis of criterion for torsional irregularity of seismic structures. 13th World conference on earthquake engineering, Vancouver, BC, Canada, 2004.
[17]   Jeong S-H, Elnashai AS. Analytical and experimental seismic assessment of irregular RC buildings. 13th World conference on earthquake engineering, Vancouver, BC, Canada, 2004.
[18]   Jeong S-H, Elnashai AS. New three-dimensional damage index for RC buildings with planar irregularities. Journal of Structural Engineering 2006;132:1482–90.
[19]   Anagnostopoulos SA, Alexopoulou C, Stathopoulos KG. An answer to an important controversy and the need for caution when using simple models to predict inelastic earthquake response of buildings with torsion. Earthquake Engineering & Structural Dynamics 2010;39:521–40.
[20]   Teddy L, Hardiman G, Tudjono S. The effect of earthquake on architecture geometry with non-parallel system irregularity configuration. vol. 99. 1st ed., IOP Publishing; 2017, p. 12004.
[21]   de Stefano M, Pintucchi B. A review of research on seismic behaviour of irregular building structures since 2002. Bulletin of Earthquake Engineering 2008;6:285–308.
[22]   Sirsikar RA, Awchat GD, Kalyana Rama JS. Parametric Study of Performance-Based Seismic Design of Plan Irregular RC Frames—Indian Scenario. Recent Advances in Earthquake Engineering, Springer; 2022, p. 427–38.
[23]   Kheyroddin A, Ezoddin AR. Study on the Effect of the Position of X-bracing Arrangement in the Steel Structures with a Triangular Plan. International Journal of Numerical Methods in Civil Engineering 2017;2:11–27.
[24]   Provisions NR. Instructional Materials. FEMA 451B–June 2007.
[25]   American Society of Civil Engineers. Minimum Design Loads for Buildings and Other Structures (ASCE/SEI 7-16). American Society of Civil Engineers; 2016.
[26]   Csi E. Integrated Software for Structural Analysis and Design. Computers and Structures Inc, Berkeley, California, USA, Sa 2000.
[27]   American Society of Civil Engineers. Seismic evaluation and retrofit of existing buildings (ASCE 41-17). American Society of Civil Engineers; 2017.
[28]   Chopra AK, Goel RK. A modal pushover analysis procedure for estimating seismic demands for buildings. Earthquake Engineering & Structural Dynamics 2002;31:561–82.
[29]   Council BSS. Prestandard and commentary for the seismic rehabilitation of buildings. Report FEMA-356, Washington, DC 2000.
[30]   Chopra AK, Goel RK. Capacity-demand-diagram methods for estimating seismic deformation of inelastic structures: SDF systems. Report No PEER1999/02 1999.
[31]   Uang C-M. Establishing R (or R w) and C d factors for building seismic provisions. Journal of Structural Engineering 1991;117:19–28.
[32]   Hilber HM, Hughes TJR, Taylor RL. Improved numerical dissipation for time integration algorithms in structural dynamics. Earthquake Engineering & Structural Dynamics 1977;5:283–92.
[33]   Center Peer. PEER ground motion database. PEER NGA-West2 Database 2013.
[34]   Kreslin M, Fajfar P. The extended N2 method considering higher mode effects in both plan and elevation. Bulletin of Earthquake Engineering 2012;10:695–715.
[35]   Council BSS. NEHRP recommended seismic provisions for new buildings and other structures. Rep FEMA P 2009;750.
[36]   de Stefano M, Marino EM, Rossi PP. Effect of overstrength on the seismic behaviour of multi-storey regularly asymmetric buildings. Bulletin of Earthquake Engineering 2006;4:23–42.