بررسي روش تركيبي نصب سطحي ورق در داخل شيار جهت تقويت برشي تير بتني مسلح با ورق هايFRP

چكيده انگليسي :

Shear strengthening of RC Beams with FRP sheets Using Externally Bonded Reinforcement In Grooves EBRIG Method Behzad Razavi b razavi@cv iut ac ir January 13 2014 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language PersianSupervisor Dr Davood Mostofinejad Prof Email address dmostofi@cc iut ac irAbstractCarbon fiber reinforced polymers have been used to strengthen or retrofit concrete parts of structures that havebeen damaged by applied loads crashes corrosion fire or settlement An easy solution to shear strengthening ofreinforced concrete beams in recent decades has been attaching carbon fiber reinforced polymers vertically ordiagonally to the sides of the beams however due to different poisson s ratios of CFRP sheets and concrete debonding of CFRP sheets accelerates Conventional Preparing of concrete surface for better connectionbetween concrete and sheet delays the debonding to some degree But In some circumstances due to high costs scale of the structure kind of target surface hard to reach position of the surface and high environmentalpollution it is impossible to use conventional surface preparation method and alternative methods must be used The history of CFRP usage for structure strengthening is not long but numerous investigations have beenconducted to better understand the behavior of reinforced structures Researchers have proposed 30 failuremodes for reinforced concrete beams strengthed with CFRP An effective parameter in debonding is the stressbetween the CFRP and the substrate By increase the contact surface between the CFRP and substrate thedebonding may be delayed In this research due to the promising results of grooving methods in delaying andcontrolling the CFRP debonding from concrete substrate grooving method is studied to evaluate its efficacy indelaying debonding and increasing the contribution of sheets in shear capacity To perform the study 15 concrete beam specimens with dimensions of 120 160 1400 mm were tested Toincrease the number of testes with existing beams external shear strengthening steel anchorage system in half ofthe span was used to make it possible to test each beam twice Three and four point loading systems were usedin different specimens and to make the comparison of the test results possible length of shear spans in all testswas taken equal to 340 mm To experience the shear failure design of beams and reinforcements wereperformed based on ACI 440 2R 08 and ACI 318 08 codes The test beams were included specimens withoutany strengthening specimens strengthened with EBR method specimens strengthened with EBROG method specimens strengthened with EBRIG method and spcimens sterengthed by a new rocedure of NSM method withCFRP sheets The last two tecchniques of strengthening were used for the first time in shear strengthening ofconcrete beams and made a prominent part of this study Attaching shear reinforcements vertically or diagonallycompared to beam axis and configuration of FRP sheets in 2 sides application U wrap and full wrap are theother important parameters that were investigated in this study Results showed that the use of the groovingmethod to install the FRP shear reinforcements increases the shear capacity up to 22 5 also increase the mid span deflection of the beam up to 60 compared to those of surface preparation method Key Words CFRP shear reinforcement concrete beam suface preparation grooving methods GM EBROG EBRIG

رضوي، بهزاد

بررسي روش تركيبي نصب سطحي ورق در داخل شيار جهت تقويت برشي تير بتني مسلح با ورق هايFRP

تقويت برشيCFRP , تقويت خارجي با قوطي فولادي , آماده سازي سطحي , شيار زني , الگوي اتصال