مطالعه آزمایشگاهی و مقایسه کاربرد غلاف GRP و دورپیچ CFRP بر رفتار ستون های بتن مسلح با مقطع دایره ای

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری عمران- سازه، گروه عمران، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران

2 دانشیار گروه عمران، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران

3 استادیار مدعو گروه عمران، واحد اهواز، دانشگاه آزاد اسلامی، اهواز، ایران و استادیار گروه عمران، دانشگاه صنعتی جندی‌شاپور، دزفول، ایران

چکیده

امروزه تقویت ستون ها با استفاده از کامپوزیت های الیاف پلیمری تقویتی، از جمله روش های تقویت در سازه محسوب می شوند. در این روش افزایش فشار محاطی بر سطح جانبی ستون های بتنی، باعث افزایش مقاومت های فشاری و کششی عضو بتنی، افزایش مقاومت در برابر کمانش و افزایش شکل پذیری این اعضاء می شود. هم چنین استفاده از لوله های پلاستیکی تقویت شده با الیاف شیشه به عنوان غلاف ستون های بتنی، علاوه بر بی نیازی به قالب‌بندی، باعث ایجاد اثر محصورکنندگی بر بتن، شکل‌پذیری و جذب انرژی بالا، کاهش جمع شدگی و خزش بتن، عدم تماس بتن با عوامل خورنده، سرعت ساخت بالا و ظرفیت باربری مناسب می گردد. در این پژوهش بر روی 6 نمونه ستون بتن مسلح استوانه ای با قطر و ارتفاع به ترتیب 150 و 600 میلی متر با و بدون غلاف GRP ،آزمایش مقاومت فشاری انجام شده و اثر دورپیچ الیاف پلیمری تقویتی کربنی بر آن ها، به عنوان عامل محصورکننده بررسی گردید. نتایج نشان داد که استفاده از دورپیچ CFRP و غالف GRP باعث بهبود ظرفیت فشاری ستون های بتن مسلح می شود. افزودن یک لایه و دو لایه دورپیچ CFRP به طور میانگین باعث افزایش %18/5 و % 26/5 ظرفیت فشاری گردید، درحالی که استفاده از غلاف GRP به طور میانگین باعث افزایش %300 در ظرفیت فشاری ستون شده است. نتایج حاکی از آن است که گرچه دورپیچ CFRP و غالف GRP هر دو ایجاد محصوریت می کنند، ولی غلاف GRP به خاطر محصوریت بالاتر، تأثیر بسیار بیشتری بر روی افزایش ظرفیت فشاری ستون های بتن مسلح دارد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

An Experimental study on the behavior of circular RCC enclosed GRP casing and FRP wrapping

نویسندگان [English]

  • Mohsen Shafieinia 1
  • Seyed Fathollah Sajedi 2
  • Seyed Vahid Razavi Toosi 3
1 Ph.D. student, Department of Civil Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
2 Associate professor, Department of Civil Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
3 Invited Assistant Professor, Department of Civil Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran and Assistant Professor, Department of Civil Engineering, Jundi Shapur University of Technology, Dezful, Iran
چکیده [English]

Nowadays, strengthening of the column using fiber-reinforced polymer (FRP) composites is considered as the strengthening technics of these loading elements in a structure. In this technique, increasing the surrounding pressure on radial levels of the concrete column increases the compressive and tensile strengths of the concrete element, reduces slenderness, and increases the buckling load and ductility of this element. Moreover, using glass-fiber reinforced plastic pipes (GRP) as the concrete column casing in addition to the independence of the need for framing leads to confinement effect on the concrete, high ductility and energy absorption, reduction in shrinkage and creep of concrete, lack of contact of the concrete with the corrosive factors, high construction speed, and proper loading capacity. In this research, a compressive capacity test was conducted on 6 cylinders reinforced concrete columns (RCC) of 150 mm and diameter 600 mm height, with and without GRP casing, and the effect of FRP wrapping was studied on them as the confining factor. The research results showed that using FRP wrapping and GRP casing improved the compressive capacity and ductility of the RCC. Adding one or two FRP wrapping layers increased the compressive capacity by 18.5% and 26.5% on the average, while using GRP casing increased the compressive capacity up to 4 times on the average and this shows that although FRP wrapping and GRP casing are both confined, GRP casing is more effective in increasing the compressive capacity due to its higher confinement with RCC.

کلیدواژه‌ها [English]

  • Reinforced Concrete Columns (RCC)
  • GRP casing
  • FRP wrapping
  • Axial force
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