کنترل ارتعاشات ناشی از باد برج‎های تلویزیونی بلند با به‎کارگیری بخشی از سازه اصلی به عنوان زیرسازه جاذب ارتعاش

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشجوی دکترا، دانشکده فنی و مهندسی، دانشگاه محقق اردبیلی، اردبیل، ایران

2 استادیار، دانشکده فنی و مهندسی، دانشگاه محقق اردبیلی، اردبیل، ایران

چکیده

در این مطالعه، روش جدیدی برای کنترل پاسخ برج‎های تلویزیونی بلند در مقابل نیروهای دینامیکی باد پیشنهاد گردید. مطابق ایده پیشنهادی، بخشی از سازه اصلی برج از آن جدا گردید و به عنوان زیرسازه جاذب ارتعاش دینامیکی در نظر گرفته شد. جهت ارزیابی روش پیشنهادی، برج 310 متری نانجینگ در کشور چین که دارای دو سکوی تماشا در ارتفاع‎های 180 و 240 متری می‎باشد، مورد مطالعه قرار گرفت. پاسخ سازه برای سه حالت کنترل نشده، کنترل شده با میراگر جرمی تنظیم شونده یا TMD، و کنترل شده توسط یک زیرسازه‎ی جدا شده از سازه اصلی در محل سکوی تماشای فوقانی، مورد تحلیل قرار گرفت. سازه برج به‎صورت تیر طره‎ای قائم چند درجه آزادی در نظر گرفته شد و زیرسازه جاذب ارتعاش به‎صورت جرم متمرکز توسط سیستم موازی سختی و میرایی به سکوی فوقانی متصل گردید. کلیه مراحل تحلیل حوزه فرکانس، بهینه‎سازی سیستم، شبیه‎سازی تاریخچه زمانی سرعت باد و تحلیل حوزه زمان، از طریق برنامه‎نویسی در محیط نرم‎افزار متلب انجام گردید. نتایج نشان می‎دهد روش پیشنهادی نسبت به سیستم TMD دارای قابلیت بیشتری در کنترل ارتعاشات سازه دارد، این سیستم به طور موثری پاسخ شتاب سازه را کاهش می‎دهد و نقش مهمی در تامین آسایش ساکنین در شرایط بحرانی نیروهای دینامیکی باد ایفا می‎کند. همچنین با توجه به اینکه در روش پیشنهادی، بخشی از جرم سازه اصلی به عنوان جاذب ارتعاش عمل می‎نماید، محدودیت‎های به‎کارگیری سیستم TMD شامل نیاز به اختصاص بخش با ارزشی از فضای برج به جادادن یک جرم اضافی سنگین و فضای لازم برای ارتعاش آن، مرتفع می‎گردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Wind-induced vibration control of tall TV towers using a part of the main structure as a vibration absorber substructure

نویسندگان [English]

  • Nahmat Khidaie 1
  • Houshyar Eimani kalehsar 2
1 PhD Candidate, Department of Civil Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
2 Assistant professor, Department of Civil Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
چکیده [English]

The present paper proposes a new control strategy to mitigate wind-induced vibrations of tall TV towers. Based on the proposed idea, a part of the main structure of the tower is isolated and regarded as a dynamic vibration absorber. In order to investigate the effectiveness of the proposed system, the 310-m tall Nanjing TV tower in China, which has two observation decks at the heights 180 m and 240 m, is studied. The wind-induced responses are obtained for the following cases: uncontrolled structure; controlled structure equipped with the TMD system; and the controlled structure with an isolated substructure at the upper observation deck level. The structure is modelled as a multi-degree-of-freedom (MDOF) lumped mass vertical cantilever beam. The TMD system and the isolated substructure are modelled as a lumped mass connected to the upper observation deck by a parallel stiffness and damper system. All the calculation works related to the frequency-domain analysis, optimizing the system, simulating the wind velocity, and the time-domain analysis are carried out using the MATLAB software. The results indicate that the proposed self-control structural system has higher vibration control capacity than the TMD system. The proposed system can effectively reduce the acceleration response of the structure and improve occupant comfort during critical wind speed. In the proposed system, since a part of the main structure performs as a vibration absorber, it is not required to assign a valuable space of the observation deck for the installation of an additional mass damper and the corresponding clearance to accommodate its large strokes.

کلیدواژه‌ها [English]

  • Wind-induced response
  • Response control
  • Dynamic vibration absorber
  • Frequency domain analysis
  • Self-control system
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