اثرات جنبش‌های پرقدرت زمین متشکل از لرزه اصلی و پس‌لرزه متوالی بر قاب‌های صلب با ساختار سازه‌ای دسته شده در حوزه نزدیک گسل

نوع مقاله : Articles

نویسندگان

1 دانشگاه خوارزمی، تهران

2 دانشکده فنی و مهندسی، دانشگاه خوارزمی، تهران

چکیده

مطالعه ساختار لرزه‌شناسی زلزله­های بزرگ رخ داده در کالیفرنیا، ژاپن و نیوزلند، این نکته عمومی را در بر دارد که سازه­ها در نواحی لرزه­خیز علاوه بر جنبش اصلی، تحت تأثیر پس­لرزه­هایی با شدت­های مختلف نیز قرار می­گیرند. زلزله­های متوالی، پاسخ غیرالاستیک سازه­ها را تحت تأثیر قرار­داده، به‌طوری‌که در بعضی از مـوارد منجـر به تجمع خسارت قابل توجـه در المان­های سازه­ای و غیرسازه­ای می­گردد. تحقیقات متعددی در ارتباط با تأثیر پس‌لرزه‌ها بر روی سازه­ها انجام شده است. نکته دیگر آنکه بیشتر مطالعات نیز بر روی سیستم­های یک درجه آزادی یا سیستم­های دو بعدی چند درجه آزادی متمرکز است. هدف این پژوهش، ارزیابی اثرات پس­لرزه بر روی پارامترهای پاسخ ساختمان­ فولادی 10 طبقه با ساختار قاب محیطی دسته­شده می­باشد. بر پایه نتایج تحلیلی این پژوهش، وقوع پس‌لرزه‌های نیرومند به‌ویژه بعد از رکوردهای حوزه نزدیک حاوی پالس سرعت، تأثیرگذاری چندانی در تغییرات پارامتر بیشینه دریفت طبقات ندارند. همچنین با اعمال تغییر در شدت پس­لرزه­ها، وقوع جابه‌جایی نسبی ماندگار در ارتفاع سازه مسیر مشخصی نخواهد داشت. در بعضی موارد، پس‌لرزه منجر به کاهش کوچک دامنه دریفت ماندگار در مقایسه با جنبش اصلی نیز می­شود. افزون بر آن، در صورت نزدیکی پریود غالب جنبش اصلی زمین به زمان تناوب سازه و یا نزدیکی پریود غالب پس­لرزه به پریود سازه خسارت دیده در اثر جنبش اصلی، آنگاه فرآیند پس­لرزه نیز دامنه رفتار غیرخطی المان­های سازه­ای را افزایش می­دهد.

کلیدواژه‌ها


عنوان مقاله [English]

The Effects of Multiple Strong Ground Motions on the Steel Modular Bundled Tube Resistant Structures in Near-Field Areas

نویسندگان [English]

  • Shahrzad Mohammadi 1
  • Afshin Meshkat-Dini 2
1 Faculty of Engineering, Kharazmi University, Tehran, Iran
2 Kharazmi University, Tehran, Iran
چکیده [English]

Study of the seismological aspects of major earthquakes occurred in California, Japan and New Zealand indicates that the structures located in regions with high level of seismicity, experience aftershocks with different intensities in addition to the mainshock. Multiple earthquakes create inelastic response in structures and lead to the accumulation of considerable damage in the structural and non-structural elements. The aim of this research is to determine the effect of aftershocks on the response parameters of a 10-story steel bundled tube frame structure. According to the analytical results of this study, the occurrence of severe aftershocks following the near-field earthquakes does not have a significant contribution to the changing maximum inter-story drift parameter. Additionally, by increasing the intensity of the aftershocks, the residual inter-story drift does not indicate a clear trend height-wise, obviously. Moreover, when the dominant period of the mainshock is close to the fundamental period of the structure, and the dominant period of the aftershock is close to the fundamental period of the damaged structure, then the occurrence of the aftershock increases the amplitude of the nonlinear response of structural elements. The response parameters studied in the current paper include maximum interstory drift, residual inter-story drift, plastic hinge mechanism and induced forces due to shear lag effect . It should be noted that the maximum inter-story drift in all stories of the studied structure subjected to the fault normal component of the Bam 2003 mainshock record has exceeded the allowable value prescribed by the Iranian seismic code 2800. This is due to the dominant period of the Bam record that is very close to the fundamental period of the studied structure. The findings of this study display that the occurrence of the aftershocks following the mainshock does not change the maximum inter-story drift considerably. Moreover, the strong aftershock (PGAas/PGAms=1.0) occurring after the Cape Mendocino 1992 mainshock i.e. PET record, increased the maximum inter-story drift at the middle and upper stories. Results apply that by changing the aftershock intensities, no clear trend in residual drift values is emerged. The reason could be attributed to the fact that the damaged structure may not have the more maximum displacement when it stops oscillating. However, the Bam mainshock record caused maximum residual drift equal to 0.024, which according to FEMA356 is beyond the Life Safety (LS) performance level.

کلیدواژه‌ها [English]

  • Near-Field Record
  • Mainshock
  • Aftershock
  • Bundled Tube
  • Residual Drift
  • Seismic Performance
  1. Hatzivassiliou, M. and Hatzigeorgiou, G.D. (2015) Seismic sequence effects on three-dimensional reinforced concrete buildings. Soil Dynamics and Earthquake Engineering, 72, 77-88.
  2. Yaghmaei-Sabegh, S. and Ruiz-Garcia, J. (2016) Nonlinear response analysis of SDOF systems subjected to doublet earthquake ground motions: A case study on 2012 Varzaghan–Ahar events. Engineering Structures, 110, 281-292.
  3. Hatzigeorgiou, G.D. and Beskos, D.E. (2009) Inelastic displacement ratios for SDOF structures subjected to repeated earthquakes. Engineering Structures, 31(11), 2744-2755.
  4. Ali, M.M. and Moon, K.S. (2007) Structural developments in tall buildings: current trends and future prospects. Architectural Science Review, 50 (3), 205-223.
  5. Ruiz-Garcia, J. and Negrete-Manriquez, J.C. (2011) Evaluation of drift demands in existing steel frames under as-recorded far-field and near-fault mainshock– aftershock seismic sequences. Engineering Structures, 33(2), 621-634.
  6. Mahin, S.A. (1980) Effects of duration and aftershocks on inelastic design earthquakes. 7th World Conference on Earthquake Engineering, Istanbul, Turkey, 5, 677-680.
  7. Fragiacomo, M, Amadio, C. and Macorini, L. (2004) Seismic response of steel frames under repeated earthquake ground motions. Engineering Structures, 26(13), 2021-2035.
  8. Hatzigeorgiou, G.D. (2010) Ductility demand spectra for multiple near-and far-fault earthquakes. Soil Dynamics and Earthquake Engineering, 30(4), 170-183.
  9. Ruiz-Garcia, J. (2012) Mainshock-aftershock ground motion features and their influence in building's seismic response. Journal of Earthquake Engineering, 16(5), 719-737.
  10. Hatzigeorgiou, G.D. and Liolios, A.A. (2010) Nonlinear behavior of RC frames under repeated strong ground motions. Soil Dynamics and Earthquake Engineering, 30(10), 1010-1025.
  11. The Iranian National Building Code (Steel Structures- Division 10), Tehran, Iran, 2014.
  12. The Iranian National Building Code (Design Loads for Buildings- Division 6), Tehran, Iran, 2014.
  13. Standard No. 2800 (2014) Iranian code of practice for seismic resistant design of buildings (4th Edition), Tehran, Iran.
  14. Mohammadi, S. (2017) Assessment of Seismic Demand Parameters of Modular Steel Building Under Strong Earthquake Records Containing the Effects of Aftrshocks. M.Sc. Thesis, Kharazmi University, Tehran, Iran (in Persian).
  15. FEMA 356 (1998) Federal Energy Management Agency (FEMA), Prestandard and Commentary for the Seismic Rehabilitation of Buildings.
  16. FEMA 440 (2005) Improvement of Nonlinear Static Seismic Analysis Procedures, Applied Technology Council (ATC-55 Project).
  17. Movahed, H., Mashkat-Dini, A., and Tehranizadeh, M. (2012) Seismic behavior of steel special moment-resisting frames affected by strong ground motions in near fault areas. 15th World Conference of Earthquake Engineering, Lisboa, Portugal.
  18. MacRae, G.A. and Mattheis, J. (2000) Three-dimensional steel building response to near-fault motions. Journal of Structural Engineering, 126(1), 117-126.
  19. Yaghmaei-Sabegh, S. (2013) Wavelet-based Analysis for Pulse Period of Earthquake Ground-motions. International Journal of Engineering-Transactions A: Basics, 26(10), 1135-1144.
  20. Azhdarifar, M., Mashkat-Dini, A., and Moghadam, A.S (2015) Assessment of Seismic response of Mid-Rise Steel Buildings with Structural Configuration of Framed Tube Skeletons. 7th International Conference on Seismology and Earthquake Engineering (SEE7), Tehran, Iran.
  21. Zafarani, H. and Soghrat, M. (2016) The selected databases of strong ground motions of Iran's earthquakes. Bulletin of Earthquake Science and Engineering, 2, 21-34 (in Persian).
  22. Hayden, C. P., Bray, J. D., and Abrahamson, N. A. (2014). Selection of near-fault pulse motions. Journal of Geotechnical and Geoenvironmental Engineering, 140(7), DOI:10.1061/(ASCE)GT.
  23. -5606.0001129.
  24. Mohammadi, S., Ahmadi, A., Azhdarifar, M., and Mashkat-Dini, A. (2016) Evaluation of drift demand of steel buildings with modular skeleton in near fault areas. 2nd National Conference on Iranian Structural Engineering, Tehran, Iran (in Persian).
  25. Ruiz-Garcia, J., Marin, M.V., and Teran-Gilmore, A. (2014) Effect of seismic sequences in reinforced concrete frame buildings located in soft-soil sites. Soil Dynamics and Earthquake Engineering, 63, 56-68.
  26. PEER Ground Motion Database, http://peer. berkeley.edu.
  27. Computer and Structures, Inc. SAP2000, Structural Analysis Program. Berkeley, CA, 2000.
  28. CSI PERFORM3D, Structural Analysis Software, Berkeley, CA, 2007.
  29. Manie, S., Moghadam, A.S., and Ghafory-Ashtiany, M. (2016) Probabilistic assessment of collapse behavior of low-rise buildings with asymmetricity in plan. Bulletin of Earthquake Science and Engineering, 2, 47-69 (in Persian).
  30. Akkar, S., Yazgan, U., and Gülkan, P. (2005) Drift estimates in frame buildings subjected to near-fault ground motions. Journal of Structural Engineering, 131(7), 1014-1024.
  31. Bojorquez, E. and Ruiz‐Garcia, J. (2013) Residual drift demands in moment‐resisting steel frames subjected to narrow‐band earthquake ground motions. Earthquake Engineering and Structural Dynamics, 42(11), 1583-1598.
  32. Ruiz-Garcia, J. (2012) Issues on the response of existing buildings under mainshock–aftershock seismic sequences. 15th World Conference on Earthquake Engineering, Lisboa, Portugal.