Seismic Assessment of Steel Moment Frames with Irregularity in Mass and Stiffness

Document Type : Original Article

Authors

1 M.sc. Candidate, Islamic Azad University, Dezful branch, Dezful, Iran

2 Assistant Professor, Girne American University, Kyrenia / TRNC, Cyprus

Abstract

Irregularity, consider to be one of the main reasons of buildings collapse in recent earthquakes. Irregularity also affects the seismic behavior and maximum capacity of structures. The effect of mass and stiffness irregularity was evaluated in this research using static and dynamic analysis. Three frames with 5, 10 and 15 stories with a 20% and 50% increase in mass of the middle stories and a 20% and 50% decrease in the ground level and middle stories were investigated separately. Maximum drift, first mode period, mass participation coefficient, and base shear force were evaluated using a developed program in MATLAB and SAP2000 based on finite element method. The results showed that changes in mass and stiffness causes a maximum increase of shear force by 14% and 5% in short and tall frames respectively. Maximum drift and the longest period in short frame occurred when the stiffness of ground level was decreased by 50 percent. In addition, such irregularity causes around 85% increase in mass participation coefficient in both short and tall frames.

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References

[1]      FEMA-356, Prestandard and Commentary for the Seismic Rehabilitation of Buildings, American Society of Civil Engineers. Federal Emergency Management Agency, Washington, DC, 2000. n.d.
[2]      CEN. Eurocode 8 (2003), Design of structures for earthquake resistance, Part 1: General rules, seismic actions and rules for buildings, European Committee for Standardization, Brussels. n.d.
[3]      Al-Ali AAK a, Krawinkler H. Effects of Vertical Irregularities on Seismic Behavior of Building Structures, Report No. 130, 1998, The John A. Blume Earthquake Engineering Center, Department of Civil and Environmental Engineering, Stanford University, Stanford, U.S.A. n.d.
[4]      Valmundsson E V., Nau JM. Seismic Response of Building Frames with Vertical Structural Irregularities. J Struct Eng 1997;123:30–41. doi:10.1061/(ASCE)0733-9445(1997)123:1(30).
[5]      Chintanapakdee C, Chopra AK. Seismic Response of Vertically Irregular Frames: Response History and Modal Pushover Analyses. J Struct Eng 2004;130:1177–85. doi:10.1061/(ASCE)0733-9445(2004)130:8(1177).
[6]      Lee H-S, Ko D-W. Seismic response of high-rise RC bearing-wall structures with irregularities at bottom stories. Proc. 13th World Conf. Earthq. Eng. Vancouver, Canada, 2004.
[7]      Athanassiadou CJ. Seismic performance of R/C plane frames irregular in elevation. Eng Struct 2008;30:1250–61. doi:10.1016/j.engstruct.2007.07.015.
[8]      Varadharajan S, Sehgal VK, Saini B. Review of different structural irregularities in buildings. J Struct Eng 2012;39:393–418.
[9]      Sarkar P, Prasad AM, Menon D. Vertical geometric irregularity in stepped building frames. Eng Struct 2010;32:2175–82. doi:10.1016/j.engstruct.2010.03.020.
[10]    Nezhad ME, Poursha M. Seismic evaluation of vertically irregular building frames with stiffness, strength, combined-stiffness-and-strength and mass irregularities. Earthquakes Struct 2015;9:353–73.
[11]     Varughese JA, Menon D, Prasad AM. Displacement-based seismic design of open ground storey buildings. Struct Eng Mech 2015;54:19–33.
[12]    Manie S, Moghadam AS, Ghafory-Ashtiany M. Collapse response assessment of low-rise buildings with irregularities in plan. Earthquakes Struct 2015;9:49–71.
[13]    Vijayanarayanan AR, Goswami R, Murty CVR. Identifying stiffness irregularity in buildings using fundamental lateral mode shape. Earthquakes Struct 2017;12:437–48.
[14]    ANSI/AISC 360-10, Specification for Structural Steel Buildings, American Institute of Steel Construction, Chicago-Illinoi, 2010. n.d.
[15]    Agrawal P, Shrikhande M. Earthquake resistant design of structures. PHI Learning Pvt. Ltd.; 2006.
Computational Engineering and Physical Modeling
Volume 1, Issue 4 - Serial Number 4
October 2018
Pages 71-89

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History

  • Receive Date: 02 August 2018
  • Revise Date: 21 December 2018
  • Accept Date: 09 January 2019

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