مطالعه ی رفتار آزمایشگاهی تیربتن مسلح تقویت شده با میلگرد GFRP، ورق‌ های CFRP و فولادی تحت خمش خالص

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی مقطع دکتری، گروه مهندسی عمران واحد مرودشت دانشگاه آزاد اسلامی، ایران

2 استادیار گروه مهندسی عمران، واحد مرودشت، دانشگاه آزاد اسلامی، مرودشت، ایران.

3 اسنادیار گروه مهندسی عمران واحد مرودشت دانشگاه آزاد اسلامی مرودشت ایران

چکیده

متداول ترین روش مقاوم سازی تیرهای بتن مسلح، تقویت خمشی این تیرها با مصالح کامپوزیت می باشد. در مقاله حاضر چهار تیر با مقیاس واقعی به ابعاد 4200*250*250 میلیمتر ساخته شده است. ابتدا یک تیرتقویت نشده در آزمایشگاه تحت بارگذاری چهارنقطه ای قرار گرفت. سپس برای تقویت تیر در ناحیه ی خمشی، از سه تیر مشابه با استفاده از یک لایه ورق CFRP، یک لایه ورق فولادی ومیلگرد GFRP در ناحیه ی خمش تقویت و مقاوم سازی شد. تقویت تیرها در محدوده‌ی میانی صورت گرفته که بعد از بارگذاری در همه ی تیرها شکست خمشی اتفاق می‌افتد. نتایج نشان داد که تقویت تیربتن مسلح به صورت موضعی در ناحیه ی خمشی تاثیر چندانی برظرفیت باربری تیر نداشته اما باعث خارج شدن خرابی از محدوده‌ی خمشی محض تیر می شود. همچنین نتایج نشان می‌دهد با انجام تقویت موضعی در ناحیه خمشی، در بعضی از تیرها پیدایش اولین ترک ها در خارج از محدوده خمشی اتفاق می افتد در حالیکه شکست خمشی نهایی در محدوده میانی تیر اتفاق می افتد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental Investigation of the Behaviour of Concrete Beams Reinforced by GFRP Bars and Strengthened by CFRP and Steel Sheets Under Pure Bending Moment

نویسندگان [English]

  • BABAK MANSORI 1
  • Ashkan Torabi 2
  • ARASH totonchi 3
1 PhD Student, Department of Civil Engineering, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
2 2. Assistant Professor, Department of Civil Engineering, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
3 اسنادیار گروه مهندسی عمران واحد مرودشت دانشگاه آزاد اسلامی مرودشت ایران
چکیده [English]

One of the conventional retrofitting methods for reinforced concrete beams is flexural strengthening of beams with CFRP materials. In this study, a full scale reinforced concrete beam is constructed and evaluated under four-point flexural test. Afterward, a same beam is retrofitted in flexural region by monolayer of CFRP. These experimental tests are carried out to be the basis of verification for numerical specimens. The first, an unreinforced beam is subjected to four-point loading in the laboratory. Then, to strengthen the beam in the flexural zone, three similar beams is reinforced and reinforced in the flexural zone using a layer of CFRP sheet, a layer of steel sheet and GFRP rebar. The reinforcement of the beams is done in the middle range, and after loading, bending failure occurred in all the beams. The results show that the reinforced concrete beam has much impact on carrying capacity, but would crash out of the range of the bending beam will be soon. The results also show that by performing local reinforcement in the flexural zone, in some beams, the first cracks occur outside the flexural range, while the final flexural failure occurs in the middle range of the beam.

کلیدواژه‌ها [English]

  • Retrofit
  • Reinforced concrete beam
  • CFRP Sheet
  • GFRP bar
  • Steel Sheet
[1] ACI Committee 440. (2017). Guide for the design and construction of externally bonded FRP systems for strengthening concrete structures: ACI 440.2 R-17. AmericanConcrete Institute.
[2] American Concrete Institute. Committee 440. (2006). Guide for the Design and Construction of Structural Concrete Reinforced with FRP Bars: ACI 440.1 R-06.” American Concrete Institute.
[3] Saliha H, Bennetta C, Matamorosb A. (2021). Evaluation of novel combined CFRP-steel retrofit for repairing distortion-induced fatigue, Journal of Constructional Steel Research, 182: 106642.
[4] Eslamia A, Shayeghb H R, Moghavema A, Ronaghc H R. (2019). Experimental and analytical investigations of a novel end anchorage for CFRP flexural retrofits, Composites Part B: Engineering, 176: 107309.
[5] Hassan H. F., Medhlom M. T. K., Ahmed A. S., & Al-Dahlaki M. H. (2020). Flexural performance of concrete beams reinforced by gfrp bars and strengthened by cfrp sheets. Case Studies in Construction Materials, 13, e00417.
[6] Ali, H, Assih J, Li A. (2021). Flexural capacity of continuous reinforced concrete beams strengthened or repaired by CFRP/GFRP sheets, International Journal of Adhesion and Adhesives, 104:102759.
[7] Elbana A, Junaid M T. (2020). Determination of flexural capacity for GFRP-reinforced concrete beams retrofitted using external CFRP sheet, Structures, 27: 1384-1395.
[8] Benmokrane B, Masmoudi R. (1996).  Flexural response of concrete beams reinforced with FRP reinforcing bars. Struct J.; 93: 46–55.
[9] M'Bazaa I, Missihoun M, Labossiere P. (1996).  Strengthening of reinforced concrete beams with CFRP sheets. First International Conference on Composites in Infrastructure National Science Foundation National Sicence Foundation.
[10] Aghabozorgi, P., Khaloo, A. (2020). Numerical investigation of the effects of compression GFRP reinforcement on the flexural strength and ductility of reinforced concrete beams. Journal of Concrete Structures and Materials, 5(1), 31-45. (In Persian)
[11] Sharifi, Y., khojastefar, E. (2018). A method to assess capacity and deflection of flexural reinforced concrete members retrofitted with FRP. Journal of Concrete Structures and Materials, 3(2), 77-88. (In Persian)
[12] Baderan, M., Varaste Poor, H. (2016). An expremental method to prevent fast fracture phenomenon in bending of carbon and glass reinforced concrete beams. Journal of Concrete Structures and Materials, 1(2), 73-82. (In Persian)
[13] Talebzadeh, M., Rostamian, M. (2018). Modeling of reinforced beams with FRP sheet and its validation with laboratory results. Civil and Architecture Conference, Tabriz, Iran. (In Persian)
[14] Kok S Leong. (2017). Effect Of Beam Size & FRP Thickness On Interfacial Shear Stress Concentration & Failure Mode In FRP Strengthened Beam" MS Thesis, Singapor.
 
[15] Pancha S., Norris T, Saadatmanesh H, Ehsani M. (2016).  Improving The Serviceability of Concrete Beams Using Carbon Fiber Reinforced Polymer (CFRP) Sheets. Federal Highway.
 
[16] Podoloski S., Taqieddin ZN. (2018). Elasto-Plastic and Damage Modeling of Reinforced Concrete Ph.D. Dissertation, Dept. Civil & Environmental Engineering, Louisiana State Univ. Baton Rouge LA.
 
[17] Jarival M., Obaidat YT, Heyden S, Dahlblom O. (2018).  The Effect of CFRP and CFRP/ Concrete Interface Models When Modeling Retrofitted RC Beams With FEM" Journal Of Composite Structures.
 
[18] Najafgholipour, S.M. Dehghan, M. Khani, A. Heidari (2018). The performance of lap splices in RC beams under inelastic reversed cyclic loading. Structures24 July.2018.07.011.
 
[19] Garsia G., Heyden S, Dahlblom O. (2019). The Effect of CFRP and CFRP/Concrete Interface Models When Modeling Retrofitted RC Beams with Fem" Journal of Composite Structures.
 
[20] Chaboki, H. R., Ghalehnovi, M., Karimipour, A., & De Brito, J. (2018). Experimental study on the flexural behavior and ductility ratio of steel fibers coarse recycled aggregate concrete beams. Construction and Building Materials, 186, 400-422.
 
[21] Jahangir, H., & Esfahani, M. R. (2020). Experimental analysis on tensile strengthening properties of steel and glass fiber reinforced inorganic matrix composites. Scientia Iranica.
 
[22] Rezaiee Pajand, M., Rezaiee-Pajand, A., Karimipour, A., & Abad, J. M. N. (2020).  A particle swarm optimization algorithm to suggest formulas for the behaviour of the recycled material reinforced concrete beams. Int. J. Optim. Civil Eng, 10(3), 451-479.
 
[23] Jahangir, H., Esfahani, M.R., (2017). Strain of Newly – Developed Composites Relationship in Flexural Tests (In Persian)” Journal of Structural and Construction Engineering, 2018; 5(Special Issue 3): 92-107.
 
[24] Bagheri, M., Chahkandi, A., and Jahangir, H. (2019). Seismic Reliability Analysis of RC Frames Rehabilitated by Glass Fiber-Reinforced Polymers. International Journal of Civil Engineering.
 
[25] Karimipour, A., & Ghalehnovi, M. (2021). Comparison of the effect of the steel and polypropylene fibres on the flexural behaviour of recycled aggregate concrete beams. Structures, 29,129-146.
 
[26] ACI 318-19. Building Code Requirements for Structural Concrete. Reported by ACI Committee318.