نویسنده
دانشکده مهندسی عمران و معماری، دانشگاه شهید چمران اهواز، اهواز
چکیده
امروزه بسیاری از مدل‌های پیچیده، به‌طور معمول مدل‌های اجزای محدود، در تحلیل سازه سکوهای جکتی استفاده شده‌اند. با این حال، این مدل‌های فراگیر و جامع به راحتی در عرف مهندسی (یعنی در عمل) به‌خصوص در مرحله طراحی اولیه به‌راحتی مورد قبول واقع نمی‌شوند. از آنجا که تحلیل دینامیکی سکوهای جکتی بسیار پیچیده است، ایجاد یک روش محاسباتی ساده برای ارزیابی عملکرد دینامیکی چنین سازه‌هایی بسیار سودمند خواهد بود. در این کار از یک مدل ساده اصلاح شده برای محاسبه پاسخهای دینامیکی سکوهای جکتی استفاده شده است. در این راستا، برای غلبه بر مشکل عدم اطمینان در مدل‌سازی، از ساده‌سازی مدل مبتنی بر داده‌های مودال ارتعاشی و معادله تیر تیموشنکو استفاده شده است. با توجه به روش برازش منحنی روی مجموعه توابع پاسخ فرکانسی برای استخراج پارامترهای مودال، از مفهوم چگالی طیف توان نیز برای تأیید مدل محاسباتی پیشنهادی استفاده شده است. در این راستا، ابتدا رفتار مدل فیزیکی در حوزه فرکانس ارائه و سپس با نتایج طیفی اخذ شده از مدل ساده شده براساس تیر تیموشنکو مقایسه شده است. چون تست مودال مدل فیزیکی تحت نیروی نویز سفید انجام گرفته است، لذا پاسخهای دینامیکی مدل ساده شده نیز تحت نیروی نویز سفید با نرم‌افزار متلب استخراج شده است. در این مقاله، یک مدل ریاضی کاربردی تولید شده است، و نشان داده شده است که مدل ساده اصلاح شده میتواند ویژگی‌های واقعی سازه‌ای را منعکس کند.
کلیدواژه‌ها
عنوان مقاله [English]
Simulation of Simplified Computational Model of Jacket Structure with Timoshenko Cantilever Beam and Experimental Signature
نویسنده [English]
- F. Hosseinlou
چکیده [English]
Today many complex models, typically finite element models, have been employed in the analysis of jacket offshore structures. However, these comprehensive models are not readily adopted in engineering practice, especially during the preliminary design stage. As the dynamic analysis of jacket platforms is very complicated, it will be very advantageous to make a simplified computational method to assess dynamic performance of such structures. In this work a refined simplified model has been utilized to calculate dynamic responses of jacket platforms. In this regard, the model simplification based on the vibration modal data and Timoshenko’s beam equation has been employed to overcome the uncertainty problem in modeling. According to the curve fitting method on the set of frequency response functions to derive modal parameters, the concept of power spectrum density has been also used to confirm the proposed computational model.In this regard, first the behavior of the physical model in the frequency domainhas been presented and compared with the spectral results obtained from the simplified model based on Timoshenko beam. Because the modal test of the physical model was performed under the force of white noise, the dynamic responses of the simplified model were also extracted under the force of white noise using MATLAB software. In this paper, an applied mathematical model has been produced, and it has been demonstrated that the refined simplified model can reflect the real structural features.
کلیدواژه‌ها [English]
- Offshore jacket platform
- Simplified computational model
- Dynamic behavior
- Vibration modal data
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