مطالعه موردی و ارزیابی دو سازه مهاربندی فولادی در زلزله بم‌ و روش‌های مقاوم‌سازی

نوع مقاله: علمی - پژوهشی

نویسندگان

1 دانشیار، دانشکده مهندسی عمران، صنعتی خواجه نصیرالدین طوسی، تهران، ایران

2 کارشناسی ارشد، دانشکده مهندسی عمران، صنعتی خواجه نصیرالدین طوسی، تهران، ایران

3 دانشجوی کارشناسی ارشد، دانشکده مهندسی عمران، دانشگاه صنعتی شریف، تهران، ایران

چکیده

در کشورهای با لرزه‌خیزی بالا مانند ایران، سازه‌های بسیاری وجود دارند که در سالهای گذشته طراحی و اجرا شده اند که به دلیل عدم تطابق با ضوابط آئین نامه، اغلب فاقد ایمنی کافی در مقابل اثرات زلزله میباشند. شناسایی و مقاوم‌سازی چنین سازههایی مقوله بسیار مهمی است که عدم توجه به آن صدمات جبران‌ناپذیری را ایجاد می‌کند. در این مقاله دو ساختمان آسیب دیده از شهر بم در زمان زلزله، انتخاب که در سه حالت ؛ الف) بر اساس شرایط واقعی موجود ب) تقویت دو سازه در سه حالت (تقویت فقط مهاربند، تقویت فقط ستون‌ها و تقویت ستون و مهاربند) ج) طراحی سازه موجود بر اساس آیین‌نامه 2800 ویرایش چهارم، تحلیل و طراحی و سپس آنالیز استاتیکی غیرخطی بر روی آنها انجام گرفت. همچنین سازه‌ها با استفاده از ورق تقویتی و میراگر ویسکوز تقویت شده که نتایج آنالیز تاریخچه زمانی غیرخطی نشان می دهد ساختمان‌های بهسازی شده با میراگر ویسکوز مایع در مقایسه با ساختمان‌های بهسازی شده با ورق تقویتی از عملکرد اتلاف انرژی نسبتاً بالاتری برخوردار می باشد. همچنین در حالت اجرای سازه با تمام ملاک‌های آیین‌نامه 2800 می‌توان ادعا کرد که سازه در برابر زلزله رفتار منطقی‌تری خواهد داشت و با تقویت ساختمان موجود هرچه ساختمان به حالت ایده آل (طراحی بر اساس آیین‌نامه) حرکت می‌کند، قابلیت تحمل نیروهای بزرگ‌تر را خواهد داشت و روند تشکیل مفاصل پلاستیک به صورت ایده‌آل انجام می‌پذیرد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Case study and Evaluation of two steel bracing systems in the Bam earthquake and methods of retrofitting

نویسندگان [English]

  • Masoud Mirtaheri 1
  • Neda Farhoudi 2
  • Meissam Nazeryan 3
1 Associate Professor, Department of Civil Engineering, K.N. Toosi University of Technology,Tehran, Iran
2 M.Sc. Student, Department of Civil Engineering, K.N. Toosi University of Technology,Tehran, Iran
3 M.Sc. Student, Department of Civil Engineering, Sharif University of Technology, Tehran, Iran
چکیده [English]

In the seismically active countries such as Iran, there are many structures that have been designed and constructed in recent years that do not conform to the terms and provisions of the design codes. On 26 December 2003 at 1:57 GMT, the historical city of Bam, located in the south-eastern region of Kerman province in Iran, was shaken by a relatively strong and destructive earthquake. This earthquake clearly demonstrated that combination of relatively rigid load-bearing external brick walls and flexible internal steel columns, existing similarly in most other regions of the country, is quite hazardous. Also the use of steel beams and columns in buildings without observing proper seismic provisions showed no improvement over non-engineering designed buildings. In this research, two steel frame buildings which had been damaged in the bam earthquake were studied. The first building has bracing system in both directions and in the second building the bracing system only exist in one direction fallowed by infilled panel with saddlebag type connection(semi-rigid Khorjini connection) in opposite direction. In both buildings all the standard of criteria 2800 and Seismic provisions are considered. Nonlinear static analysis (Pushovers) and nonlinear time-history analysis are implemented on both structures. After determining the vulnerability of structures, using steel plates and viscous damper, the results show that retrofitted buildings with fluid viscous damper dissipate higher energy in comparison with the buildings retrofitted by the steel plate. Strengthening the existing buildings were investigated and compared with each others through three different methods: 1. replacing relatively strong bracing system with the relatively weaker bracing 2. Strengthening the columns by adding cover steel plates to the columns of building and 3. Global Strengthening bracing and columns system of buildings.

کلیدواژه‌ها [English]

  • Steel structures
  • retrofitting
  • viscous damper
  • Nonlinear time history analysis
  • Nonlinear static analysis

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