تأثیر جایگزینی کامپوزیت سیمانی الیافی توانمند به جای بتن معمولی در بهبود رفتار آزمایشگاهی تیرهای دوسرگیردار بتنی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجو دکترا /دانشگاه سمنان

2 دانشگاه سمنان

چکیده

رفتار سخت‌شوندگی کرنش تحت نیروی کششی بتن کامپوزیتی HPFRCC و ریزترک‌های قبل از گسیختگی و جذب انرژی بالا در آن‌ها توجیه استفاده این بتن توانمند الیافی می‌باشد. در این مقاله اثر استفاده از این بتن کامپوزیتی با الیاف با حجم ۱ و 2 درصد بر رفتار خمشی تیرهای بتنی گیردار مورد مطالعه قرار گرفت. مجموعاً 4 تیر بتنی دوسرگیردار به طول 1/85 متر (با دو ستونک با صلبیت بالا در دو انتها) در نظر گرفته شدند که دو نمونه مرجع با بتن معمولی با دو نوع فاصله خاموت‌ها در دو انتهاء تیر (d/2 و d/4) و 2 تیر هم با بتن HPFRCC با مقدار الیاف 1 و 2 درصد با فاصله خا موت‌ها برابر d/2 به‌صورت غیر فشرده بودند. مقاومت فشاری متوسط دو نوع بتن تقریباً برابر بودند. نوع بارگذاری به ‌صورت استاتیکی و در وسط دهانه اعمال شد و در حین آزمایش نیز گیرداری دو سر تیر با استفاده از تمهیداتی مرتباً کنترل ‌گردید. نتایج آزمایشات نشان داد که استفاده از بتن HPFRCC با الیاف ۱ و ۲ درصد بجای بتن معمولی باعث افزایش شکل‌پذیری و جذب انرژی تیرهای گیردار شد و شکل‌پذیری جابه‌جایی تیرها با 1 و 2 درصد الیاف (HC1 و HC2) به ترتیب تا 54 و 100 درصد افزایش یافت؛ درحالی‌که این اعداد برای شکل‌پذیری انرژی 74 و 200 درصد بودند. ضمناً طول مفصل پلاستیک در تیرهای HC1 و HC2 نسبت به تیر با بتن معمولی و فاصله غیر فشرده میلگردها به ترتیب 35 و 47 درصد افزایش یافت.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Replacement Effect of High-Performance Fiber-Reinforced Cementitious Composite with Ordinary Concrete on Improving the Experimental Behavior of Two Fixed-Ends Concrete Beams

نویسندگان [English]

  • Amir Ghods 1
  • Mohammad Kazem Sharbatdar 2
1 PhD Student/ Faculty of Civil Engineering/Semnan University
2 Semnan University
چکیده [English]

In this paper, the effect of high-performance fiber-reinforced cementitious composite (HPFRCC) with 1 and 2% of steel fibers on the flexural behavior of two fixed-ends concrete beams was investigated. Four beams were cast and tested under concentrated load, two conventional beams, and two HPFRCC beams (with 1 and 2% steel fibers) with two different stirrups spacing in the plastic zone. The average compressive strength is 55 MPa in HPFRCC beams and 50 MPa in conventional concrete beams, and the mixing design was considered so that the strengths of all samples were the same. The type of loading was statically and in the middle of the span. Two fixed-end beams were arranged with a beam of 1.85 m in the middle and two rigid columns of 0.3 m on the sides, which were connected to the frame by using 16 bolts of 22 mm to ascertain the rigidity of the problem, during the test, this rigidity was regularly controlled by the use of measures. The results of the experiments indicated that the use of 1 and 2% fibers in the HPFRCC concrete increased the ductility and absorption of energy. As the displacement ductility increased by 54 and 100% in HC1 and HC2, increasing in energy ductility was 74 and 200% due to the use of more fibers and causing smaller cracks in concrete, and improving its strength properties. By adding fiber, the length of the plastic hinge of the beams was increased 35 to 47%.

کلیدواژه‌ها [English]

  • Two fixed-end
  • High performance
  • Reinforced concrete
  • Steel fibers

مراجع

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نشریه مهندسی عمران امیرکبیر
دوره 53، شماره 11
بهمن 1400
صفحه 4875-4894

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