بررسی خرابی پیش رونده در قاب های بتن آرمه با درنظرگرفتن نواحی صلب انتهایی و انواع مختلف سناریوهای حذف زمانی ستون

نوع مقاله : علمی - پژوهشی

نویسندگان

1 استادیار گروه مهندسی عمران، دانشگاه رازی، کرمانشاه، ایران

2 دانشجوی کارشناسی ارشد سازه، دانشگاه رازی، کرمانشاه، ایران

چکیده

دراین پژوهش به بررسی پارامترهای نواحی صلب انتهایی و مدت زمان حذف ستون در خرابی پیش رونده قاب‌های بتن‌آرمه پرداخته شده است. به دلیل بزرگ بودن ابعاد تیرها و ستون ها در ساختمان های بتن آرمه نمی توان از اثر ناحیۀ صلب انتهایی آن ها صرفنظر نمود. مدت زمان حذف ستون نیز از دیگر پارامترهایی است که با توجّه به علّت وقوع حادثه می‌تواند مقادیر متفاوتی را به خود اختصاص دهد که در این مطالعه حذف ستون‌ها به صورت ناگهانی، آیین‌نامه‌ای و تدریجی بررسی گردید. برای این منظور دو قاب بتن‌آرمۀ 4 و 8 طبقه در نرم‌افزار OpenSees مدلسازی شدند. در هر کدام از این دو قاب، با حذف ستون میانی و گوشه به بررسی میزان تأثیر نواحی صلب انتهایی و مدت زمان حذف ستون‌ها پرداخته شد. در بررسی نواحی صلب انتهایی برای ارزیابی سختی قائم سازه و دوران تیرها با درنظرگرفتن سطح عملکرد، از تحلیل دینامیکی غیرخطی و برای ارزیابی ظرفیت سازه از تحلیل استاتیکی غیرخطی بارافزاینده قائم استفاده گردید. در بررسی پارامتر زمانِ حذف ستون نیز از تحلیل دینامیکی غیرخطی برای بررسی سختی قائم و بررسی سطح عملکرد تیرها استفاده شد. پس از تحلیل قاب‌ها مشخّص شد که نواحی صلب انتهایی تأثیر بسزایی را در افزایش سختی قائم در سازه داشته است؛ این در حالی است که این تأثیر در دوران تیرها و ظرفیت سازه نقش کمتری را ایفا کرده است. مدت زمان حذف ستون نیز نقش مؤثری را در مقدار بیشینه تغییرمکان قائم داشته است. این تأثیر در حذف تدریجی به صورت کاملاً آشکارا دیده شده است اما در حذف ناگهانی و آیین‌نامه‌ای، اختلاف بسیار ناچیز بوده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of progressive collapse in reinforced concrete frames, considering end rigid zones and various scenarios for column removal duration

نویسندگان [English]

  • Hamid Reza Ashrafi 1
  • Seyed Ali Hassanzadeh 2
1 Assistant Professor, Dept. of Civil Engineering, Razi University, Kermanshah, Iran
2 MSc student, Civil Eng. Department, Faculty of Engineering, Razi University, Kermanshah, Iran
چکیده [English]

In this study, some researches about end rigid zones parameters and column removal duration in progressive collapse reinforced concrete frames are taken place. Due to massive dimensions of beams and columns in reinforced concrete frames, the effect of end rigid zones cannot be ignored. Column removal duration is one of the variables that can have different values considering the cause of an accident in which this study it is assessed in conditions such as suddenly, standard and gradually removal. Therefore, two 4- and 8-storey reinforced concrete frames are designed via OpenSees Software. The impact of end rigid zones and column removal duration in either frames has been evaluated by removal of the middle and corner column. In order to evaluate end rigid zones for determining vertical stiffness of structure and beams rotation considering performance level, nonlinear dynamic analysis is used. In addition, to assess structural capacity, nonlinear static analysis of increasing load is applied. To evaluate column removal duration, nonlinear dynamic analysis is used to assess the vertical stiffness and performance level of beams. After analyzing the frames, it was shown that the end rigid zone can have a great impact on increasing vertical stiffness; while having much lower influence on beam rotation and structural capacity. Column removal duration can also have an impressive effect on maximum value of vertical displacement. This effect is highly demonstrated in gradually removal; however there is a slight difference in suddenly and standard removal.

کلیدواژه‌ها [English]

  • Progressive collapse
  • Reinforced concrete frame
  • End rigid zones
  • column removal duration
  • Nonlinear dynamic analysis
  • Vertical stiffness
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