بررسي راهكارهاي عملي براي استفاده بهتر از ورق هاي تقويتي CFRP و CERPدر محصور شدگي ستون هاي بتن آرمه ي دايروي

چكيده انگليسي :

123 Practical Methods to Improve Performance of FRP Confined Circular RC Columns Hamid karimizadeh a karimizadeh@cv iut ac ir December 30 2013 Department of Civil Engineering Isfahan University of technology Isfahan 84156 83111 Iiran Degree M Sc Language Persian Supervisor Dr Mohammadreza Eftekhar Assistant Prof Email Address eft@cc iut ac ir Advisor Dr Davood Mostofinejad Prof Email Address dmostofi@cc iut ac irAbstract With increasing advances in polymer science and materials engineering the use of polymer compositesin construction is increasing day by day Two main types of composites made of carbon and glass fibers forreasons such as high strength good ductility and low cost they are mostly used in the construction industry The main application of these materials is increase the strength and ductility of the structural components Inrecent years strengthening and improvement the columns as a most important structures components hasbeen the subject of much research Confining decreases lateral expansion of columns and increases the loadcapacity and ductility of them considerably Today in addition to confining different methods and materialsused in the column confining the study is to find ways through which they can gain the maximum capacityof the composite can be obtained The composites used in the columns never can not to show their realpotential in operation This object in addition to created problems in the design of columns makes the projecteconomically to face challenges Various factors are effective in reducing the capacity of composites Of themost important of these factors can pointe to multi axial stresses which enters to the composite andtransmission stress concentration of cracks to the FRP during column loading So if we use the appliedprocedure to prevent transmission of multi axial stress and concentration stress in the FRP the FRP can berecovered much of the lost capacity In the present study in order to improvement performance of FRPcomposite we have tried to reduce the biaxial stresses exerted on the reinforcing sheet and to avoid from thetransition stress concentration caused by the concrete surface cracking to reinforcing plate too In this studygalvanized sheet with thickness of 0 13 mm and compressed rubber with thickness of a millimeter is usedas an intermediate layer which were cut almost similar to the size of the reinforcing sheet and were insertedunder them To achieve the objectives of the study 27 cylindrical reinforced concrete specimens with 150 mmdiameter and 500 mm height were tested under pure axial load Columns were reinforced with carbon andglass fibers by different techniques In some reinforced samples has been used from intermediate layer andsome of them without the use of intermediate layer and have been strengthened conventional In this study inaddition to surveying the types of fibers the intermediate layer type and the effect of the gap between theconcrete surface and intermediate layer the reinforcing effect of the number of layers the effect of stripwidth as well as the effect of additional strengthening of the middle region of the column has beeninvestigated The results showed that the use of intermediate layer in samples reinforced with 1 layer of carbon fiberincreases the loading capacity by 53 and the energy absorption by 16 compared to samples withoutintermediate layer In samples reinforced with a layer of glass fiber intermediate layer increased loadcapacity by 17 and energy absorption 117 compared to samples without intermediate layer Comparisonof the results obtained from these experiments show that the performance of the intermediate layer inspecimens reinforced with glass fiber is higher than specimens reinforced with carbon fibers Key Words circular Reinforced concrete columns FRP axial loading load capacity ductility intermediate layer galvanized sheets rubber compression

كريمي زاده، حميد

بررسي راهكارهاي عملي براي استفاده بهتر از ورق هاي تقويتي CFRP و CERPدر محصور شدگي ستون هاي بتن آرمه ي دايروي

FRU , بارگذاري محوري , ظرفيت باربري , شكل پذيري , لايه ي مياني , ورق گالوانيزه