بررسی تاثیر انواع الیاف در بهبود رفتار خمشی تیرهای بتنی بازیافتی در نواحی الاستیک و پلاستیک

نوع مقاله : علمی - پژوهشی

نویسندگان

1 کارشناس ارشد مهندسی عمران، دانشگاه لرستان، خرم آباد، ایران

2 گروه مهندسی عمران-دانشگاه لرستان

3 دانشجوی دکتری مهندسی عمران، دانشگاه صنعتی نوشیروانی، بابل، ایران

4 استادیار، گروه مهندسی عمران، دانشگاه لرستان

چکیده

این مقاله به ارائه نتایج یک تحقیق آزمایشگاهی در مورد رفتار خمشی تیرهای بتنی حاوی سنگدانه‌های بازیافتی و مسلح شده به انواع الیاف‌ها می‌پردازد. در این تحقیق 5 عدد تیر بتنی با طول 150، عرض 20 و ارتفاع 30 سانتی متر ساخته شد. یک تیر حاوی سنگدانه‌های طبیعی و فاقد الیاف بعنوان نمونه شاهد، یک تیر حاوی سنگدانه‌های بازیافتی و فاقد الیاف و سه تیر دیگر حاوی سنگدانه‌های بازیافتی و مسلح شده به 5/0 درصد از هرکدام از الیاف‌های فولادی، پلی‌پروپیلن و کورتا بودند. رفتار تیرها تحت آزمایش خمش 4 نقطه‌ای در دو ناحیه الاستیک و پلاستیک بررسی شد. پارامترهای حد تناسب، مدول برجهندگی، مدول الاستیسیته خمشی و لنگر تسلیم در ناحیه الاستیک و پارامترهای لنگر نهایی، شکل‌پذیری، جذب انرژی و ضریب طاقت خمشی در ناحیه پلاستیک بررسی شدند. تیرهای معمولی و بازیافتی در تمام پارامترهای مذکور دارای اختلاف اندک (کمتر از 10 درصد) بودند. از طرفی، الیاف‌های مورد استفاده موجب تقویت رفتار خمشی تیرها در هر دو ناحیه الاستیک و پلاستیک شدند که تاثیر الیاف فولادی نسبت به الیاف‌های پلی‌پروپیلن و کورتا قابل توجه‌تر بود. در نهایت، نتایج تجربی بدست آمده در این تحقیق با آیین ‌نامه‌های بتن ایران، ACI 318، EuroCode 2 و CSA مقایسه شد. نتایج این مقایسه نشان داد که بیشترین تطابق با نتایج تجربی مربوط به آیین ‌نامه ACI 318 و بیشترین اختلاف مربوط به آیین ‌نامه EuroCode 2 می‌باشد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigating the effect of different types of fibers in improving the flexural performance of recycled concrete beams in the elastic and plastic zones

نویسندگان [English]

  • Abbas Eskandari 1
  • Amirhosein Sahraei moghadam 3
  • Ahmad Dalvand 4
1 M.Sc., Faculty of Engineering, Lorestan University, Khorramabad, Iran
3 Ph.D student, Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
4 Assistant professor, faculty of engineering, lorestan university,khorramabad, iran
چکیده [English]

This paper presents the results of an experimental investigation on the flexural performance of concrete beams containing recycled aggregates concrete (RCA) and reinforced with a variety of fibers. In this research, 5 concrete beams with a length of 150, width 20 and height 30 cm were made. One beam containing natural aggregate (NA) and fiber-free as control specimen, one beam containing RCA and fiber-free and the other three beams containing RCA and reinforced with 0.5% of each of the steel, polypropylene and korrta fibers. The performance of the beams were investigated under four-point bending test in two elastic and plastic zones. The parameters of limit of proportionality, modulus of resilience, flexural modulus of elasticity and yield moment in the elastic zone and the parameters of the ultimate moment, ductility, energy absorption and flexural toughness in the plastic zone were investigated. Beams containing NA and RCA had a slight difference (less than 10%) in all the mentioned parameters. On the other hand, the fibers used improved the flexural performance of the recycled beams in both elastic and plastic zones, which the effect of steel fiber was more significant than polypropylene and korrta fibers. Finally, the experimental results obtained in this study were compared with the results of Iranian Concrete Code (ABA), ACI 318, EuroCode 2 and CSA. The results of this comparison indicated that the lowest difference with the experimental results is related to ACI 318 and the highest difference is related to EuroCode 2.

کلیدواژه‌ها [English]

  • Recycled Concrete
  • RCA
  • Flexural Performance
  • Steel Fiber
  • Polypropylene fiber
  • Korrta fiber
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