ارزیابی رفتار دینامیکی مخازن ذخیره مایعات جداسازی شده با سیستم آونگ اصطکاکی تحت تحریکات پالس‌گونه

نوع مقاله : مقاله کامل پژوهشی

نویسندگان

دانشکده مهندسی عمران، دانشگاه تبریز

چکیده

سیستم‌های جداسازی به عنوان یکی از روش‌های مؤثر و معمول برای کاهش خسارات انواع سازه‌ها از جمله مخازن ذخیره مایعات شناخته شده است. با این وجود، این نوع سازه‌های جداسازی شده تحت تحریکات پالس‌گونه و پریود بلند زلزله‌های حوزه نزدیک گسل، در معرض آسیب‌های احتمالی هستند. هدف از این تحقیق ارزیابی پارامتریک و جامع پاسخ لرزه‌ای مخازن ذخیره مایعات جداسازی شده با سیستم آونگ اصطکاکی (FPS) تحت تحریکات پالس‌گونه می‌باشد. برای این منظور ابتدا مخازن جداسازی شده با مدل‌های مکانیکی معادل شبیه‌سازی شده و سپس آنالیز دینامیکی غیرخطی آن‌ها تحت چنین تحریکاتی انجام می‌شود. تأثیر متغیرهای مهم پالس‌های ورودی و سیستم جداسازی مانند دامنه پالس، پریود پالس، تعداد پالس، پریود جداسازی، ضریب اصطکاک جداسازی و نیز تأثیر نسبت ‌ابعادی مخزن ارزیابی می‌شود. نتایج حاصله بیانگر این است که با اضافه کردن سیستم جداسازی، می‌توان پاسخ‌های لرزه‌ای مخازن را تحت تحریکات پالس‌گونه معادل زلزله‌های حوزه نزدیک گسل در محدوده مطلوبی کنترل کرد. همچنین مشاهده شد که جابجایی قائم سطح آزاد سیال با توجه به بالا بودن زمان تناوب نوسانی تحت تأثیر تحریکات با پریود بلند است؛ درصورتی­که لنگر واژگونی مخزن تحت تأثیر و تشدید پالس‌های با پریود نزدیک به پریود جداساز هستند. با تغییر مشخصه‌های سیستم جداسازی مخزن و مشاهده تأثیر آن‌ها در حداکثر پاسخ‌های در نظر گرفته­شده، توصیه‌هایی برای انتخاب مناسب آن‌ها در مجاورت گسل‌های فعال صورت گرفت.

کلیدواژه‌ها


عنوان مقاله [English]

Dynamic Behavior Evaluation of FPS Isolated Liquid Storage Tanks Subjected to Pulse-like Excitations

نویسندگان [English]

  • Hossein Hayati Raad
  • Saman Bagheri
Faculty of Civil Engineering, University of Tabriz, Tabriz 5166616471, Iran
چکیده [English]

On-grade liquid storage tanks are vulnerable to strong ground motions, as some recent major earthquakes have demonstrated. Seismic base isolation is one of the most efficient techniques to mitigate earthquake damage in these structures. Among the various base isolation devices, the Friction Pendulum System (FPS) provides several benefits: the independence of isolation period from superstructure mass/weight which can be varied in some structures such as liquid storage tanks, re-centering related to the spherical surface, and high energy dissipation based on velocity-dependent friction (Mokha et al., 1991; Zayas et al., 1990). Although the base isolation has been known as an efficient technique to protect civil structures, the performance of base-isolated structures under near-fault ground motions containing long-period pulses has been questioned in recent years. In this paper, a parametric study is carried out to investigate the seismic behavior of FPS isolated liquid storage tanks under near-fault ground motions represented by analytical pulse-like functions. For this purpose, the liquid storage tanks are modeled using equivalent mechanical models and then dynamic analyses of the models are done using pulse-like excitations. The effects of the tank type, isolator specifications and the input excitation characteristics on the various response parameters are investigated.

کلیدواژه‌ها [English]

  • Liquid storage tanks
  • Base isolation
  • Friction pendulum system
  • Near-fault earthquake
  • Pulse-like excitation

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