رابطه‌سازی کرنش کامپوزیت‌های نوین الیافی در آزمون‌های خمشی

نوع مقاله: علمی - پژوهشی

نویسندگان

1 دانشجوی دکتری مهندسی سازه، دانشکده عمران، دانشگاه فردوسی مشهد، مشهد، ایران

2 استاد، دانشکده عمران، دانشگاه فردوسی مشهد، مشهد، ایران

چکیده

پلیمرهای تقویت شده با الیاف، FRP، به علت دارا بودن ویژگی‌های مکانیکی مناسب، نصبی آسان و نسبت مقاومت به وزن بالا، معمول‌ترین گونه از کامپوزیت‌ها هستند که برای تقویت و بهسازی کاربری‌های سازه‌ای استفاده می‌شوند. در کنار این برتری‌ها، مقاومت کم در برابر آتش، ناتوانی در اعمال بر روی سطح‌های مرطوب و در دماهای پایین را می‌توان از کاستی‌های کامپوزیت‌های FRP دانست. از این رو، کامپوزیت‌های نوین پایه سیمانی تقویت‌شده با الیاف با ویژگی‌ها و برتری‌های خود نسبت به کامپوزیت‌های FRP، در سال‌های اخیر جایگزینی مناسب برای آن‌ها به حساب می‌آیند. در این مقاله، در راستای شناخت بیشتر رفتار این کامپوزیت‌ها، رابطه‌ای بین کارایی نمونه‌های تقویت‌شده به کمک این کامپوزیت‌ها در آزمون خمشی و نتیجه‌های آزمون برشی به‌دست آمد. برای این منظور، نتیجه‌های آزمون خمشی سه‌نقطه‌ای چندین نمونه تیر بتن‌آرمه‌ی تقویت‌شده با یک لایه از کامپوزیت‌های نوین الیافی به کمک تحلیل مقطع وارسی شدند و رابطه‌ای برای محاسبه‌ی کرنش الیاف در آن‌ها پیشنهاد شد. از طرفی، کرنش‌های الیاف در نمونه‌های مختلف تقویت‌شده با کامپوزیت‌های مشابه در آزمون‌های برش مستقیم محاسبه و اندازه‌گیری شد. مقایسه‌ی نتیجه‌ها به‌دست آمده از رابطه‌ی پیشنهادی در آزمون خمشی با نتیجه‌های آزمون برش مستقیم نشان می‌دهند که رابطه‌ی پیشنهادی به خوبی کرنش الیاف را پیش‌بینی می‌کند.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Strain of newly – developed composites relationship in flexural tests

نویسندگان [English]

  • Hashem Jahangir 1
  • Mohammad Reza Esfahani 2
1 Ph.D. Student of structural engineering, Ferdowsi University of Mashhad, Mashhad, Iran
2 Professor of civil engineering, Ferdowsi University of Mashhad, Mashhad, Iran
چکیده [English]

Extending service life and preventing demolition of existing structures are the primary goals of structural strengthening and rehabilitation. Fiber-reinforced polymer (FRP) composites have been the most common type of composite in the realm of structural strengthening applications. In recent years, as a new type of composite, epoxy is replaced by an inorganic matrix, named fiber reinforced cementitious mortar (FRCM), and have attracted a great deal of interest among researchers. Focusing of these kind of novel composites, this paper tries to find a connection between FRCM composites behaviour, as their maximum fiber strain, in flexural and direct shear tests. To achieve this goal, a cross section analysis of previous research works on strengthened RC beams with one layer of composites was conducted and the maximum strain of the fibers was obtained. Calculated fiber strains in flexural strengthening specimens compared with corresponding measured maximum fiber strains in direct shear test specimens. Comparison of results show that the average of maximum fiber strain obtained from flexural specimens is in good agreement with corresponding one measured in direct shear test specimens. Consequently, maximum fiber strains could be designated as the lost link between flexural and direct shear tests as two separated part of a chain.

کلیدواژه‌ها [English]

  • Flexural test
  • Direct shear test
  • FRCM Composites
  • Section Analysis
  • Fiber Strain

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