تاثیر آرایش نوارهایFRP، ابعاد تیر و مقدار آرماتور کششی در ظرفیت برشی تیر بتن مسلح

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، واحد نجف آباد، دانشگاه آزاد اسلامی، نجف آباد، ایران

2 گروه مهندسی عمران، واحد نجف آباد، دانشگاه آزاد اسلامی، نجف آباد

چکیده

در ایـن مقالـه، بـه بررسـی اثـر فواصـل قـرار گیـری نوارهـای FRP ،تعداد الیه و سـطح مقطـع آن، میزان آرماتـور طولی، ابعـاد تیـر و مقاومـت فشـاری بتـن در ظرفیـت برشـی تیرهـای بتنـی بـا مقطـع مسـتطیلی شـکل تحـت بـار متمرکـز متقـارن، مقـاوم شـده بـا نوارهـای FRP بـه روش اجـزاء محـدود پرداختـه شـده اسـت. بدیـن منظـور تحلیـل غیـر خطـی 101 نمونـه، جهـت ارزیابـی تاثیـر متغیرهـای فـوق بـر ظرفیـت باربـری و تغییرمـکان وسـط دهانـه تیرهـای مختلـف بـا و بـدون نـوار تقویـت انجـام شـده اسـت. نتایـج حا کـی از آن اسـت کـه بـه ازای مقاومـت فشـاری ثابـت بـرای بتـن، افزایـش عـرض نـوار تقویتـی و افزایـش تعـداد الیـه هـای آن افزایـش ظرفیـت باربـری نسـبت بـه نمونـه هـای کنتـرل دسـته خـود را بـه همـراه دارد،. بـا تغییـر در چیدمـان نوارهـای تقویتـی بـا فواصـل نامنظـم در طـول تیـر، افزایـش ظرفیـت باربـری در حـدود 6 %الـی 35 %حاصـل مـی شـود. همچنیـن افزایـش در میـزان آرماتـور طولـی از مقـدار 10ϕ بـه 14ϕ ،افزایـش مقاومـت فشـاری بتـن از مقـدار 30MPa بـه 50MPa ،و افزایـش سـطح مقطـع تیـر از مقـدار 300mm×150 بـه 400mm×150 در نمونـه هـای تقویـت نشـده سـبب افزایـش ظرفیـت باربـری بـه ترتیـب در حـدود 31 ،%23 ،%55 %و کاهـش تغییرمـکان وسـط دهانـه مـی گـردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effect of FRP Strips Configuration, Beam Dimensions and Amount of Tensile Rebars on Shear Capacity of Reinforced Concrete Beams

نویسندگان [English]

  • Mehrdad Hejazi 1
  • Mitra Mohammad 2
1 Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad, Iran
2 Dept of Civil Engineering/Islamic Azad University, Najafabad Branch
چکیده [English]

In this paper, the effect of the distance, number of layers and cross-sectional area of FRP strips, the amount of longitudinal rebars, dimensions of beam and compressive strength of concrete on shear capacity of reinforced concrete beams with rectangular crosssection stiffened by FRP strips under symmetrical concentrated loads using the finite element method has been studied. For this reason, the non-linear analysis of 101 reinforced beams has been performed for evaluation of the effect of the parameters on load capacity and mid-span deflection of the beams with and without strengthening. Obtained results indicate that for a constant concrete compressive strength, increasing the width and the number of layers of FRP strips increases the load capacity compared to the control beam. By changing the layout of reinforcing strips with irregular intervals along the beam, the load capacity increase is about 6% to 35%. Also, the increase of the amount of longitudinal rebars from Φ10 to Φ14 creasing the compressive strength of the concrete from 30 MPa to 50 MPa, and increasing the cross-sectional area of the beam from 150 × 300 mm to 150 × 400 mm in unstiffened beams, increase the load capacity by 31%, 23% and 55%, respectively.

کلیدواژه‌ها [English]

  • Reinforced Concrete Beam
  • FRP Strips
  • Tensile Rebar
  • Shear Capacity
  • Ductility
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