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
[1] A.H. Mattock, Redistribution of design bending moments in reinforced concrete continuous beams, Proceedings of the Institution of Civil Engineers, 13(1) (1959) 35-46.
[2] A. Naaman, Setting the Stage, Toward Performance Based Classification of FRC Composites, in:  High Performance Fiber Reinforced Cement Composites (HPFRCC 4), Proc. of the 4th Int. RILEM Workshop, 2003.
[3]  G. Chanvillard, S. Rigaud, Complete characterization of tensile properties of Ductal UHPFRC according to the French recommendations, in:  Proceedings of the 4th International RILEM workshop High Performance Fiber Reinforced Cementitious Composites, (2003), 21-34.
[4] V.C. Li, From micromechanics to structural engineering-the design of cementitous composites for civil engineering applications  (1993).
[5] G. FISCHER, W. Shuxin, Design of engineered cementitious composites (ECC) for processing and workability requirements, in:  Brittle Matrix Composites 7, Elsevier, (2003) 29-36.
[6] J. Bolander Jr, 28 Spring network model of fiber-reinforced cement composites, in:  PRO 6: 3rd International RILEM Workshop on High Performance Fiber Reinforced Cement Composites (HPFRCC 3), RILEM Publications, (1999) 341.
[7] L. Vandewalle, Test and design methods for steel fibre reinforced concrete. Recommendations: Bending test, Materials and structures, 33(225) (2000) 3-5.
[8] K. Habel, P. Gauvreau, Response of ultra-high performance fiber reinforced concrete (UHPFRC) to impact and static loading, Cement and Concrete Composites, 30(10) (2008), 938-946.
[9] A. Hemmati, A. Kheyroddin, M.K. Sharbatdar, Plastic hinge rotation capacity of reinforced HPFRCC beams, Journal of Structural Engineering, 141(2) (2015) 04014111.
[10] A. Hemmati, A. Kheyroddin, M. Sharbatdar, Y. Park, A. Abolmaali, Ductile behavior of high performance fiber reinforced cementitious composite (HPFRCC) frames, Construction and Building Materials, 115 (2016) 681-689.
[11] T. Lou, S.M. Lopes, A.V. Lopes, Evaluation of moment redistribution in normal-strength and high-strength reinforced concrete beams, Journal of Structural Engineering, 140(10) (2014) 04014072.
[12] B. EN, 1-1. Eurocode 2: Design of concrete structures–Part 1-1: General rules and rules for buildings, European Committee for Standardization (CEN), (2004).
[13] D. Mostoufinezhad, F. Farahbod, Parametric study on moment redistribution in continuous RC beams using ductility demand and ductility capacity concep (2007).
[14] S.A.o. Australia, Australian Concrete Structures Code AS 3600-1994, in, Standards Association of Australia Sydney, Australia  (1994).
[15] B. Standard, BS 8110: Structural Use of Concrete, Part 1, Code of Practice for Design and Construction, BSI, (1997).
[16] A. Committee, Building code requirements for structural concrete (ACI 318-14) and commentary, in, American Concrete Institute, (2014).
[17] C.e.-i.d. béton, F.I.d.l. Précontrainte, CEB-FIP model code 1990: Design code, Thomas Telford Publishing, (1993).
[18] R. Ehsani, M. Sharbatdar, A. Kheyroddin, Ductility and moment redistribution capacity of two-span RC beams, Magazine of Civil Engineering, 90 (6) (2019).
[19] E.K. Schrader, D.R. Lankard, Inspection and Analysis of Curl in Steel Fiber Reinforced Concrete (SFRC) Airfield Pavements, Bekaert Steel Wire Corp., Pittsburgh, (1983).
[20] D. Lankard, Prediction of the flexural strength properties of steel fibrous concrete, in:  Proceedings of the CERL conference on fibrous concrete, construction engineering research laboratory, Champaign, (1972) 101-123.
[21] R. Swamy, P. Mangat, C.K. Rao, The mechanics of fiber reinforcement of cement matrices, Special Publication, 44 (1974) 1-28.
[22] C.H. Henager, T.J. Doherty, Analysis of reinforced fibrous concrete beams, Journal of the Structural Division, 102(ASCE# 11847), (1976).
[23] S.P. Shah, J.I. Daniel, Design considerations for steel fiber reinforced concrete, ACI Structural Journal, 85(5) (1988) 563-579.
[24] W.I. Khalil, Y. Tayfur, Flexural strength of fibrous ultra high performance reinforced concrete beams, ARPN Journal of Engineering and Applied Sciences, 8(3) (2013) 200-214.
[25] B.H. Oh, Flexural analysis of reinforced concrete beams containing steel fibers, Journal of structural engineering, 118(10) (1992) 2821-2835.
[26] M. Fakharifar, A. Dalvand, M. Arezoumandi, M.K. Sharbatdar, G. Chen, A. Kheyroddin, Mechanical properties of high performance fiber reinforced cementitious composites, Construction and Building Materials, 71 (2014) 510-520.
[27] M. Pokhrel, M.J. Bandelt, Material properties and structural characteristics influencing deformation capacity and plasticity in reinforced ductile cement-based composite structural components, Composite Structures, 224 (2019) 111013.