ارزیابی پارامترهای لرزه‌ای قاب‌های خمشی فولادی بر اساس FEMAP695 تحت زلزله‌های نزدیک گسل دوران داده شده

نوع مقاله: علمی - پژوهشی

نویسندگان

1 دانشیار، دانشگاه سمنان

2 کارشناس ارشد مهندسی عمران، دانشگاه سمنان

3 استادیار، موسسه آموزش عالی جهاد دانشگاهی خوزستان

چکیده

ضریب رفتار یکی از پارامترهای طراحی لرزه‌ای است که عملکرد غیرخطی سازه‌ها را حین زلزله‌های شدید لحاظ می‌کند. در اکثر آیین‌نامه‌های طراحی لرزه‌ای از ضریب رفتار برای لحاظ نمودن عملکرد غیرخطی سازه‌ها در تحلیل‌های خطی استفاده می‌شود. هدف از این پژوهش محاسبه پارامترهای لرزه‌ای سازه تحت زلزله‌های دور و نزدیک گسل (دوران داده شده در راستای موازی و عمود بر گسل) با استفاده از روش ارائه ‌شده در FEMAP695 و مقایسه نتایج حاصل با مقادیر آیین‌نامه‌ای است. به همین منظور از 5 قاب خمشی فولادی با تعداد طبقات 4، 7، 10، 15 و 20 و شکل‌پذیری متوسط استفاده شده است. به‌منظور استخراج منحنی ظرفیت سازه‌ها از روش تحلیل استاتیکی غیرخطی تطبیقی ( Displacement-based Adaptive Pushover Analysis, DAP) استفاده شده است. همه‌ی تحلیل‌های غیرخطی با استفاده از نرم‌افزار OpenSees انجام شده است. نتایج حاصل نشان می‌دهد ضریب رفتار تحت زلزله‌های مورد بررسی با افزایش ارتفاع سازه کاهش می‌یابد. میانگین اختلاف ضریب رفتار حاصل از زلزله‌های دور و نزدیک گسل مقدار 5/6 درصد و به دلیل بیشتر بودن ضریب رفتار حاصل از زلزله‌های دور از گسل است. همچنین ضریب رفتار حاصل از زلزله‌های نزدیک راستای موازی با گسل (Strike Parallel, SP) از زلزله‌های راستای عمود بر گسل (Strike Normal, SN) بیشتر است به ‌نحوی ‌که میانگین این اختلاف در سازه‌های مختلف در حدود 4 درصد است.

کلیدواژه‌ها


عنوان مقاله [English]

Evaluation of seismic parameters of steel moment resisting frames based on “FEMA P-695” under near-field rotated ground motion

نویسندگان [English]

  • M. Gerami 1
  • A. H. Mashayekhi 2
  • N. Siahpolo 3
1 Associat professor, Department of Earthquake Engineering, Semnan University
2 MSc graduate,, Department of Earthquake Engineering, Semnan University
3 Assistant professor, Department of Civil Engineering, ACECR Institute for Higher Education, Khuzestan branch
چکیده [English]

Behavior factor (R) is one of the seismic design parameters that considers nonlinear performance of structures during an earthquake. In most of the seismic design codes, behavior factor has been used for considering nonlinear performance of structures in linear analyses. The purpose of this study is an evaluation of seismic parameters of structures under far-field and near-field ground motions (rotated to fault strike‑normal and fault strike‑parallel) based on the method presented in FEMA P‑695 and comparing the results with those in the code. Thus, five intermediate steel moment resisting frames with 4, 7, 10, 15, and 20 stories were considered. The capacity curve of each model were obtained by Displacement- based Adaptive Pushover Analysis.  All of the nonlinear analyses were conducted by OpenSees. The results state that the behavior factor due to the ground motions used in this study decreases as the structure’s height increases. Average of difference of behavior factor in far-field ground motions and average of behavior factor in near-field ground motions is 6.5 percent and the reason is that the behavior factor in far-field ground motions is greater. Also, the behavior factor in fault strike-parallel near-field ground motions (SP) is greater than fault strike-normal near-field (SN) and the average of this difference for different structures is almost 4 percent.

کلیدواژه‌ها [English]

  • Behavior factor (R factor)
  • Displacement modifier factor
  • Displacement-based adaptive pushover analysis
  • FEMA P-695
  • Overstrength factor

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