بررسی آیین‌نامه‌ای و آزمایشگاهی اتصالات تیر عریض بتنی به ستون

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری سازه، دانشکده مهندسی عمران، پردیس دانشکده های فنی، دانشگاه تهران، تهران، ایران

2 دانشیار دانشکده مهندسی عمران، پردیس دانشکده های فنی، دانشگاه تهران، تهران، ایران

چکیده

در این مقاله، عملکرد لرزه‏ای تیرهای عریض مورد بررسی قرار می‏‌گیرد. ابتدا ضوابط آیین‌‏نامه‏‌های طراحی و آزمایش‏‌های پیشین انجام شده روی اتصالات تیر عریض بتنی به ستون مورد مطالعه قرار گرفته است. پس از بررسی دقیق نتایج آزمایش‏‌های سابق و به منظور شناخت دقیق‏‌تر رفتار نمونه‏‌های اتصال عریض، 4 نمونه‏‌ی اتصال تیر عریض به ستون در مقیاس 3:5 ساخته شد و تحت بار ثابت ثقلی و بار جانبی رفت و برگشتی مورد آزمایش قرار گرفت. نمونه‌‏ها مطابق ACI 318-14 و ACI 352R-02 طراحی و جزئیات‏بندی شدند. در 4 نمونه‌‏ی آزمایشگاهی، هندسه‏‌ی متفاوت برای ستون (مربعی، مستطیلی و دایره‏ای) و تیر عرضی (عریض یا معمولی) در نظر گرفته شد. در طول آزمایش‏‌های انجام گرفته، تشکیل مفصل پلاستیک خمشی در تمامی عرض تیر عریض در تمامی نمونه‌‏ها مشاهده شد. جذب انرژی نمونه‏‌ها نسبتاً بالا بوده که این مسأله به دلیل استفاده از آرماتورهای عرضی در موضع اتصال و بار محوری موجود ستون می‌‏باشد. عریض بودن یا نبودن تیر عرضی و نیز هندسه‌‏ی ستون‌‏ها از عوامل تأثیرگذار در رفتار لرزه‏ای نمونه‌‏های آزمایشگاهی بوده است. مقایسه نتایج آزمایشگاهی با ضوابط آیین‌‏نامه‌ای نشان می‌‏دهد که نسبت ابعادی ارائه شده توسط آیین‌‏نامه‏‌ی ACI 318 برای تیرهای عریض قابل تغییر می‌‏باشد. به علاوه در اتصالات با بار محوری بیشتر از 15 درصد، عملکرد آرماتورهای طولی ستون از نظر مهار، بهبود پیدا کرده و می‌‏توان ضوابط ACI 352R در این زمینه را تخفیف داد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Code Investigation and Experimental Study of Wide Beam-Column Connections

نویسندگان [English]

  • Ali Pakzad 1
  • Khan Mohammadi Mohammad 2
1 PHD candidate,school of Civil Engineering, University of Tehran, Tehran, Iran
2 Associate professor, school of Civil Engineering, University of Tehran, Tehran, Iran
چکیده [English]

In this paper, the seismic behavior of wide beams was investigated. First, code provisions and results of previous tests on reinforcement concrete wide beam-column connections were reviewed. After a precise investigation of previous test results and a detailed study of the behavior of wide joints, 4 specimens of exterior wide beam-column connections on a scale of 3:5 were cast and tested under constant axial and cyclic lateral loads. The specimens were designed and detailed under ACI 318-14 and ACI 352R-02. In tested specimens, different geometries for columns (square, rectangular or circular) and spandrel beams (wide or conventional) were considered. During the tests, the formation of the full-width flexural plastic hinge of wide beams was observed in all the specimens without any shear or torsional failure. Energy absorption of specimens was relatively high and that is because of using stirrups at the joint area and axial loads applied to columns. The width of the spandrel beam and geometry of columns influenced the seismic performance of tested specimens. A comparison between experimental results and ACI provisions showed that dimensional limitations of ACI 318 on wide beams can be violated. Also, in wide joints with an axial load ratio greater than 15%, the bond performance of column longitudinal bars is improved, and ACI 352R provisions in this context can be relaxed.

کلیدواژه‌ها [English]

  • Wide beam
  • Exterior beam-column connection
  • spandrel beam
  • seismic performance
  • reinforcement detailing
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