الگوی بازتوزیع بارها در یک قاب خمشی بتن آرمه در اثر اعمال پروفیل های نشست سه بعدی ناشی از گودبرداری

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد مهندسی سازه، دانشکده مهندسی، دانشگاه کاشان، کاشان، ایران

2 گروه مهندسی عمران، دانشکده مهندسی، دانشگاه کاشان، ایران

چکیده

یکی از مسائل مهم در حیطه مهندسی سازه، شناخت الگوی بازتوزیع نیروهای داخلی در اجزای باربر ساختمان پس از مواجهه با حوادث نامعمول است. از جمله این وقایع می‌توان به بروز نشست‌های تفاضلی ناشی از گودبرداری در مجاورت قاب‌های خمشی بتنی متداول در نواحی شهری اشاره نمود. با این وجود، بخش عمده‌ای از پژوهش‌های موجود صرفا به بررسی نشست در زیر یک ستون پرداخته و یا بر اثرات پروفیل‌های مربوط به عبور تونل‌های شهری بر روی قاب‌های دو بعدی تمرکز نموده‌ا‌ند. در این مقاله، با استفاده از دو سری پروفیل نشست واقعی متناظر با انجام گودبرداری عمیق (با نام‌های متوسط و بزرگ) و تعریف 8 حالت مختلف تحلیلی، مقادیر نشست تفاضلی به صورت گام به گام در زیر هر یک از ستون‌ها اعمال شدند. بدین منظور، علاوه بر پروفیل‌های نشست 3 بعدی انتخابی، برای موقعیت قرارگیری سازه نسبت به لبه گود دو وضعیت (در گوشه یا بر روی محور تقارن) و برای راستای پلان ساختمان نیز دو حالت در نظر گرفته شد. بر پایه‌ یافته‌های مدل‌های عددی، همزمان با کاهش شدید نیروی محوری فشاری در مجموعه‌ای از ستون‌های با نشست زیاد، ستون‌های غیرمجاور و غیر هم محور با ستون‌ دارای حداکثر نشست نیز نقش قابل ملاحظه‌ای در بازتوزیع بارها ایفا نمودند. علاوه بر این، تحمیل پروفیل نشست بزرگ در برخی از حالات به ایجادکشش در برخی از ستون‌ها منجر گردید. همچنین تغییر علامت لنگر خمشی تیرها در حداقل یکی از وجوه اتصال به ستون دارای نشست حداکثر و نیز در مجاورت سایر ستون‌های سازه، احتمال بروز آسیب در محدوده وسیعی از پلان را آشکار ساخت.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Load redistribution pattern in a RC moment frame due to excavation-induced 3D ground surface settlement profiles

نویسندگان [English]

  • Mahdi Arezoomand 1
  • Alireza Pachenari 2
1 M.Sc. student, Department of Civil Engineering, Faculty of Engineering, University of Kashan, Kashan, Iran
2 Department of Civil Engineering, Faculty of Engineering, University of Kashan, Kashan, Iran
چکیده [English]

Following abnormal events, identification of load redistribution pattern in the load-bearing elements is an important issue in the field of structural engineering. As a possible event, one can imply to initiation of excavation-induced large differential settlements under the columns of common reinforced concrete (RC) moment frames. A large portion of existing literature have studied the effect of single-column settlement scenarios or tunnel-induced ground movements on 2D frames, however. Using two series of real ground surface settlement profiles (called medium and large) representing deep excavation adjacent to the construction site, 8 analysis cases were defined to gradually impose differential settlements under the columns in this paper. Apart from different 3D settlement profiles, the structure was assumed to be located on the corner or center of excavation edge, and two directions were also considered for the building plan. Based on the findings of the numerical models, the axial compressive force significantly decreased in a series of highly settled columns. Also the columns which were relatively far from the location of maximum settlement made key contribution to redistribution of loads. Moreover, a large number of columns experienced tensile axial forces in some of the cases with larger surface settlement imposed. The change in the direction of beam flexural moments in conjunction with some columns (not limited to the column having the largest settlement) shed light on possibility of damage in an extensive area of the building plan.

کلیدواژه‌ها [English]

  • Excavation
  • 3ِD Settlement Profile
  • Redistribution of Loads
  • Concrete Moment Frame
  • Inelastic Behavior
  • Fiber Element Model

مراجع

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  • تاریخ دریافت: 03 آذر 1399
  • تاریخ بازنگری: 22 اسفند 1399
  • تاریخ پذیرش: 18 فروردین 1400

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