معرفی یک سیستم لرزه بر مهاربندی شده به منظور بهبود عملکرد لرزه‌ای در قاب‌های فولادی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه مهندسی عمران، واحد اراک، دانشگاه آزاد اسلامی، اراک، ایران

2 گروه مهندسی عمران، واحد ملایر، دانشگاه آزاد اسلامی، ملایر، ایران

3 گروه مهندسی عمران،واحد اراک،دانشگاه آزاد اسلامی،اراک ،ایران

چکیده

یکی از روشهای کاهش نیروی زلزله استفاده از سیستمهای قاب مهاربندی زانویی میباشد. در این روش، اعضای قطری مهاربند به عضو زانویی متصل می‌شود. وظیفه اعضای مهاربندی ایجاد سختی و وظیفه عضو زانویی ایجاد شکل پذیری همانند یک میراگر تسلیم-شونده می‌باشد. در این روش با ترکیب مهاربند‌های دروازه‌ای (Y شکل) با اعضای زانویی به نتایج جدیدی دست یافتیم. در این راستا سه نمونه قاب مهاربندی پیشنهادی در محل آزمایشگاه سازه تحت آزمایش تجربی مطابق پروتکل بارگذاری ATC-24 قرار گرفت که نتایج مؤید عملکرد مطلوب این سیستم لرزهای به همراه جذب انرژی و رفتار مناسب در پایداری این طرح می‌باشد و از ظرفیت خوبی در استهلاک انرژی برخوردار است و در جابجایی های کمتر قاب، المان زانویی سریعتر فرایند جذب انرژی را آغاز می نماید. استفاده از سیستم مهاربند زانویی به دلیل راحتی در تعویض می تواند جایگزین مناسبی برای سیستم مهاربندی باشد. رفتار منحنی های هیسترزیس تغییر شکل- نیرو نتایج مطلوبی حاصل می نماید که آزمایشات تجربی نشان داد که این سیستم دارای تعدیل نیروی فراوان خواهد بود. ترکیب قاب پیشنهادی چون سختی اولیه و مقاومت بالایی ندارند، بنابراین در زلزله‌های با شدت کم نیز عملکرد خوبی خواهند داشت. با بررسی مقادیر مختلف پاسخ های سازه ها، مکانیزم شکست سازه در محدوده قسمت پلاستیک سیستم مهاربند زانویی از شکل پذیری قابل قبولی برخوردار بودند. همچنین در این نوع مهاربند نشان داده شد که با حرکت کردن گره میانی به سمت گوشه قاب و افزایش خروج از مرکزیت این نقطه، سختی قاب کمتر شده و در نتیجه پریود ارتعاش طبیعی مهاربند افزایش و در پی آن جابجایی سیستم تحت بار ثابت افزایش می‌یابد. در جهت سنجش روش پیشنهادی با سیستم های رایج یک قاب با مهاربند قطری نیز در نرم افزار المان محدود آباکوس مدلسازی گردید که نتایج نشان دهنده رفتار خوب این سیستم است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Introducing a Seismic Bracing System in order to improve Seismic Performance of Steel Frames

نویسندگان [English]

  • Mehdi Ghiasvandan 1
  • Mehdi Alirezaei 2
  • Mohammad Mirhosseini 3
  • Ehsanollah Zeighami 1
1 Department of Civil Engineering, Islamic Azad University, Arak, Iran
2 Department of Civil Engineering, Islamic Azad University, Malayer, Iran
3 Head of Department of Masters and Doctor of Civil Engineering, Islamic Azad university, Arak. Iran
چکیده [English]

One way to reduce seismic force is to use knee bracing systems. In this method, the diagonal limbs of the brace are connected to the knee joint. The duty of the brace is to create stiffness and the duty of knee member is to create ductility like a yielding damper. In this method, some novel results are achieved by combining Y type bracing with the knee members. In this regard, three samples of the proposed frame were tested in the laboratory of structure based on the ATC24 loading protocol. The results show that this seismic system has a good performance in energy absorption and stability. At lower frame displacements, the knee element begins the absorb energy process faster. The use of a knee bracing system can be a good alternative to the brace system due to its ease of replacement. The behavior of the hysteresis (force-displacement) curves obtained from the experimental tests show good results in force balancing. Moreover, due to relatively lower initial stiffness and strength, the proposed frame will perform well in low-intensity earthquakes. It was observed that the failure mechanism of the structure has an acceptable ductility in the plastic part of the system. In addition, it was shown that by moving the middle node towards the corner of the frame and increasing the eccentricity of this point, the stiffness of the frame decreases and as a result, the natural vibration period and system displacement increases under constant load.

کلیدواژه‌ها [English]

  • knee
  • bracing
  • frame
  • hysteresis
  • curve
  • experimental
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