بررسی عَدمِ قطعیّت در نقشه‌ خطر طرحِ لرزه‌ای بر اساس منحنی‌های خطر و شکنندگی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استادیار، دانشکده فنی و مهندسی، دانشگاه صنعتی قم، قم، ایران.

2 استاد، پژوهشگاه بین‌المللی زلزله‌شناسی و مهندسی زلزله، تهران، ایران.

10.22091/cer.2024.11285.1572

چکیده

در هر اندازه‌گیری مهندسی، عدم قطعیت حضور دارد؛ خواه به آن توجه شود، خواه از قلم بیفتد. اگر در برآورد بار طرح برای یک سازه، معیاری از جنس ریسک قرار داده و عدم قطعیت آن نیز محاسبه گردد، روش انجام را روش ریسک‌مبنا و بار طرح حاصل را بار طرح ریسک‌مبنا می‌نامند. برای نمونه، در استاندارد معتبر ASCE/SEI 43-05، در طراحی لرزه‌ای کارخانه‌های هسته‌ای، از روش‌ ریسک‌مبنا برای تهیه طیف طرح لرزه‌ای، استفاده شده است. یک لازمه در این روش، در نظرگیری عدم قطعیت، چه در مدل جنبش زمین (یعنی منحنی خطر) و چه در ظرفیت سازه (یعنی منحنی شکنندگی) است. تحقیق حاضر، نخست جزئیات این روش شامل در نظر گرفتن شکل کامل منحنی خطر زلزله و نحوه دخالت دادن پاسخ سازه‌ مورد نظر در تعیین بار طرح لرزه‌ای را بررسی می‌کند. سپس، به یک مدل احتمالی دست یافته می‌شود به‌طوری که بتوان از آن برای برآورد عدم قطعیت در بار طرح لرزه‌ای، بهره برد. با کمک مدل احتمالی به‌دست ‌آمده در این مقاله، نقشه عدم قطعیت موجود در زلزله طرح، برای کشور ایران، تهیه و ارائه گردید. عدم قطعیت در بار طرح لرزه‌ای در کشور ایران، براساس اطلاعات و فرضیات موجود در مطالعه حاضر، حداقل برابر ۴۵ درصد به‌دست آمد که یک مقدار قابل‌توجه است. به عبارت دیگر، مشاهده شد در شتاب مبنای طرحی که در طراحی لرزه‌ای سازه‌ها در گستره ایران به‌کار گرفته می‌شود، از ۴۵ تا ۹۰ درصد امکان تغییر وجود دارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigating Uncertainty in Seismic Design Maps Based on Hazard and Fragility Curves

نویسندگان [English]

  • Alireza Zarrineghbal 1
  • Hamid Zafarani 2
1 Assistant Professor, Department of Civil Engineering, Faculty of Technology and Engineering, Qom University of Technology, Qom, Iran.
2 Professor of Earthquake Engineering & Engineering Seismology, IIEES, Tehran, IR IRAN.
چکیده [English]

All engineering measurements carry inherent uncertainty, whether acknowledged or not. If we add a type of risk metric as well as uncertainty quantification in the procedure of establishing the seismic design load applied to the structures, we will have a risk-informed approach for the resulting design load referred to as the risk-based seismic design hazard. For example, ASCE/SEI 43-05 standard uses a risk-based approach to prepare the seismic design spectra to be applied to the nuclear power plants (NPPs). This approach necessitates the propagation of uncertainty in ground motion model (i.e., the hazard curve), as well as probabilistic distribution of structural capacity levels (i.e., the fragility curve). The present research begins with the specifics of this approach, in particular the whole shape of the earthquake hazard curve and its integration with the structural fragility curve for estimating the seismic design load. The aim is to identify for a probabilistic model that can estimate the uncertainty of seismic design loads for a variety of engineering structures. This paper presents the estimated uncertainties of seismic design loads across the Iran map using the developed probabilistic model. The uncertainty, according to the study's assumptions, is at least 45% in terms of the coefficient of variation, indicating a significant value. The estimated variability in seismic design loads in the Iran region ranges from 45% to 90%.

کلیدواژه‌ها [English]

  • Seismic hazard
  • Risk based design
  • Uncertainty
  • Design map
  • Seismic loading
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