بررسی اثر واکنش قلیایی-سیلیسی بر روی رفتار سازه ای تیرهای بتنی مسلح با استفاده از روش المان محدود

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشگاه آزاد اسلامی واحد رودهن، تهران، ایران

2 دانشکده مهندسی عمران، دانشگاه صنعتی امیرکبیر، تهران، ایران

3 دانشکده مهندسی عمران، دانشگاه UTM مالزی، جوهور، مالزی

چکیده

واکنش قلیایی-سیلیسی یک واکنش شیمیایی است که در بین برخی از سنگدانه های سیلیکایی و محلول های قلیایی موجود در بتن رخ می دهد. این واکنش باعث انبساط بتن شده و در نهایت منجر باعث ترک خوردگیِ و کاهش ایمنی, عمر و مقاومت آن می شود. مدلسازی رفتار سازه ای بتنِ متاثر از واکنش قلیایی-سیلیسی به علت دخالت پارامترهای متعدد در این واکنش امری مشکل است. یکی از عوامل مهم در مدلسازی این واکنش پیش بینی مناسب نحوه گسترش تنش ها و کرنش ها در بتن می باشد. هدف اصلی این مقاله بررسی تاثیر مخرب واکنش قلیایی-سیلیسی بر روی رفتار سازه ای تیرهای بتنی مسلح با دو روش آزمایشگاهی و مدل سازی عددی; و بر اساس روش های تحلیل سازه ای متداول می باشد. برای این منظور, ابتدا تعدادی نمونه تیر در یک آزمایشگاه ساخته شد و پس از تحلیل سازه ای نمونه ها با روش های متداول, یک مدل عددی برای تیرها در برنامه "Ansys" با روش المان محدود ارائه شد. نتایج مدل سازی عددی همگرایی خوبی را با نتایج آزمایشگاهی نشان می دهد, اگرچه در ناحیه کششی سازگاری بهتری در مقایسه با نواحی فشاری وجود دارد و استفاده از آرماتورهای فشاری باعث افزایش سازگاری بین نتایج می شود. ضمنا قرار دادن نیروی معادل بر روی تار خنثی در مدلسازی عددی می تواند کرنش در نواحی فشاری را بهبود بدهد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigation of the Effect of Alkalai- Silica Reaction on Structural Behavior of Reinforced Concrete Beams Using the Finite Element Method

نویسندگان [English]

  • S. Hajighasemali 1
  • A. A. Ramezanianpour 2
  • V. Lotfi 2
  • M. H. Kashefizadeh 3
1 Department of Civil Engineering, Islamic Azad University (Roudehen Branch), Tehran, Iran
2 Faculty of Civil Engineering, Amirkabir University of Technology, Tehran, Iran
3 Department of Civil Engineering, UTM University of Malaysia, Skudai, Malaysia
چکیده [English]

Many structures, such as dams, bridges and hydraulic structures, suffer deterioration induced by the alkali-aggregate reaction (AAR), which impairs the durability and safety of installations. ASR is an internal chemical reaction between certain forms of siliceous aggregates and alkaline pore solution in concrete. The result is a more or less crystallised silico-alkaline product which can exert pressure on the surrounding matrix. ASR induces concrete expansion and generally leads to loss of strength and cracking. The structural behaviour of concrete which has been effected by the alkali-silica reaction (ASR) is difficult to model due to various random parameters that govern this chemical process. The aim of this paper is to investigate the effect of ASR on the behaviour of reinforced concrete beams using three methods: an experimental model, conventional structural analysis and the finite element method. For this purpose, 100 x 150 x 1100-mm concrete beams were built in the laboratory and reinforced with different ratios of compression and tension bars. Then ASR and creep strains were modelled by reducing the elastic modulus of the concrete and applying an equivalent tension force. For the purposes of verifying the numerical methods involved, fourteen beams were conditioned in a suitable environment using similar dimensions and loading systems. Experimental results on reactive concrete samples were simulated so as to test whether the model was capable of describing the behaviour of affected reinforced concrete beams under service loads. The comparison revealed that the finite element model had good compatibility with the acquired test results.

کلیدواژه‌ها [English]

  • Alkali silica reaction (ASR)
  • Finite element analysis
  • finite element modeling
  • Modeling of ASR
  • Reinforced Concrete Beams

مراجع

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نشریه مهندسی عمران امیرکبیر
دوره 49، شماره 1
خرداد 1396
صفحه 23-34

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