مطالعه پارامتریک رفتار دینامیکی مخازن ذخیره مایعات تحت تحریکات پالس‌گونه

نوع مقاله : علمی - پژوهشی

نویسندگان

گروه سازه، دانشکده مهندسی عمران، دانشگاه تبریز، تبریز، ایران

چکیده

مخازن ذخیره سیالات به طور گسترده برای ذخیره مایعات مختلف همانند فرآورده‌های نفتی در صنایع استفاده می‌شوند و صدمه دیدن آنها پیامدهای خطرناکی را به همراه خواهد داشت. زلزله‌های حوزه نزدیک گسل با دارا بودن پالس‌های شدید سرعت، پتانسیل آسیب زدن به چنین سازه‌هایی را دارند. این نوع تحریکات زمین می‌توانند به صورت توابع تحلیلی پالس‌گونه ارائه شوند. در این تحقیق رفتار لرزه‌ای مخازن ذخیره سیالات تحت چنین تحریکات پالس‌گونه بصورت پارامتریک بررسی می‌شود. برای این منظور ابتدا مخازن با مدل‌های مکانیکی معادل شبیه‌سازی شده و سپس آنالیز دینامیکی آنها تحت این نوع تحریکات انجام می‌شود. مدل تحلیلی پالس انتخاب شده بر پایه توابع موجک بوده که دارای چهار ویژگی دامنه، پریود، شکل و تعداد پالس است. تاثیر هر یک از این متغیرها در انواع پاسخ‌های دینامیکی و نیز تاثیر نسبت ابعادی مخزن ارزیابی می‌شود. نتایج حاصله بیانگر این است که پالس‌هایی با پریود بلند با توجه به بالا بودن زمان تناوب مود نوسانی، جابجایی قائم سطح آزاد سیال و پالس‌هایی با پریود کوتاه به لحاظ پایین بودن زمان تناوب ضربانی، برش‌پایه و ممان واژگونی را تحت تاثیر و تشدید قرار می‌دهند. همچنین با افزایش تعداد پالس، پاسخ‌ها در حوالی پریود پالس نزدیک به زمان تناوب نوسانی افزایش چشمگیری می‌یابند. این در حالی است که شکل پالس از نظر متقارن یا پاد متقارن بودن تاثیر محسوسی بر نتایج حاصل ندارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Parametric study on dynamic behavior of liquid storage tanks subjected to pulse-like excitations

نویسندگان [English]

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

Liquid storage tanks are widely used to store different types of liquids such as petroleum products. Any failure of these structures may cause serious consequences. Near-fault ground motions which may have severe velocity pulses have a destructive potential on these facilities and can be represented by analytical pulse-like functions. In this paper, a parametric study is carried out to investigate the seismic behavior of liquid storage tanks under pulse-like excitations. 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 selected analytical pulse-like excitation is based on the modified Gabor Wavelet transform with four main characteristics: amplitude of the signal, period of the signal, shape (phase) of the signal, and the number of pulses. The effect of each pulse parameter as well as the effect of tank aspect ratio on the various response parameters is investigated. The obtained results indicate that the sloshing motion of the liquid near the free surface is affected more by equivalent pulses with long periods while the base shear and overturning moment are affected more by equivalent pulses with short periods. It is also seen that by increasing the number of pulses, the response parameters increase considerably when the pulse period is near the natural period of the convective mode. However, changing the phase of input signals in order to produce symmetric or anti-symmetric pulses has not any noticeable effect on the obtained results.

کلیدواژه‌ها [English]

  • Liquid storage tanks
  • Near-fault earthquake
  • Pulse-like excitation
  • Structure-fluid interaction
  • Seismic response
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