بررسی اثرات لایۀ میانی در محصورشدگی ستونهای بتن آرمۀ تقویت‌شده با ورقه های CFRP

نوع مقاله : پژوهشی

نویسندگان

دانشگاه صنعتی اصفهان

چکیده

امروزه استفاده از مواد کامپوزیتی پلیمری (FRP) به‌عنوان یک مادۀ تقویتی برای تعمیر و تقویت اجزای مهم سازه های بتن آرمه
به خصوص ستون ها، رواج گسترده ای پیدا کرده است. در این تحقیق با انجام آزمایش بارگذاری محوری، تأثیر لایه ی میانی بر بهبود رفتار محصورشدگی ستون های بتن آرمه بررسی شده است. برای این هدف، 14 عدد ستون بتن آرمه به قطر 150 و ارتفاع 500 میلی متر و به
روش های مختلف توسط یک یا دو لایه ورقFRP تقویت‌شده و تحت بار فشاری محوری قرار گرفته است. در این رابطه تأثیر محصورشدگی با نوارهای منقطع CFRPدر حالت سنتی (بدون استفاده از لایۀ میانی) و با استفاده از شیوۀ نوین بررسی شده در تحقیق حاضر، با یکدیگر و با نتایج بارگذاری ستون های با تسلیح داخلی و بدون تقویت خارجی (به‌عنوان نمونه شاهد) مقایسه شده است. روش جدید شامل استفاده از یک لایه ورق نازک گالوانیزه به ضخامت 13/0 میلی متر می باشد که با نصب این ورق در زیر نوار FRP از انتقال تمرکز تنش ناشی از ترک خوردگی بتن به ورق FRP ممانعت می شود. وجود لایه میانی ضمن کاهش انتقال تنش های دومحوره به ورق FRP، باعث افزایش قابل توجه مقاومت و شکل‌پذیری نمونه های تقویت‌شده با لایۀ میانی نسبت به نمونه های تقویت‌شده در حالت سنتی می شود.

کلیدواژه‌ها


عنوان مقاله [English]

Intermediate Layer Effects in Performance of FRP-Confined RC Columns

نویسندگان [English]

  • hamid karimizadeh
  • mohammad reza eftekhar
Isfahan University of Technology
چکیده [English]

The use of polymer composite (FRP) as a reinforcement material for the repair and strengthening of important components of reinforced concrete structures, particularly columns, has found wide spread. In this study, the effect of intermediate layer on improving the confinement behavior of reinforced concrete columns has been investigated. To achieve the objectives of the study, 14 cylindrical reinforced concrete specimens with 150 mm diameter and 500 mm height were tested under pure axial load. The columns have been classified into four groups and were reinforced by one or two layers of carbon fibers and then to investigate the research topic, confinement with intermittent CFRP strips was performed in both traditional (Without intermediate layer) and modern method examined in the present study and the results were compared together and with the results of loading columns with internal reinforcement and without external reinforcement (the control sample). The new method involves using a thin layer of galvanized sheet (thickness 0.13 mm) which is mounted under the FRP sheet to prevent the transmission of stress concentration induced cracking concrete to FRP Sheets.The middle layer reduces the transfer of biaxial stress to FRP sheettoo. The results suggest that specimens reinforced with FRP and galvanized sheets have higher strength and ductility than specimens reinforced with FRP and without Galvanized.

کلیدواژه‌ها [English]

  • RC column, Intermediate layer
  • Confinement
  • CFRP Composite
  • Compressive Strength
  • Ductility
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