روش تركيبي نصب سطحي ورق در داخل شيار ﴿EBRIG ﴾ جهت اتصال ورق هاي FRP به تير بتني

چكيده انگليسي :

Externally Bonded Reinforcement In Grooves EBRIG Technique to Attach FRP Laminates to Concrete Beams Seyed Masoud Shameli sm shameli@cv iut ac ir April 20 2011 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Dr Davood Mostofinejad Assoc Prof Email address dmostofi@cc iut ac irAbstractFiber Reinforced Polymer FRP composites are widely accepted as a promising and easy to use constructionmaterials especially for strengthening purposes due to the numerous advantages such as high tensile strength ease of application light weight and corrosion resistance One of the most common methods for flexuralstrengthening of concrete beams with FRP materials is the Externally Bonded Reinforcement EBR method The main problem that has greatly hampered the use of EBR method is the premature debonding of FRPlaminate from the beam substrate This will shorten the expected lifespan of the reinforced membrane andmakes EBR method uneconomical Surface preparation of concrete before attaching FRP sheets is considered asa suitable method to postpone debonding in EBR technique but with limited effects Near Surface Mounted NSM method is another flexural strengthening technique for reinforced concretestructures The NSM technique can provide a significant increment of the load at serviceability limit state aswell as the stiffness after concrete cracking In terms of the debonding issue experiments have shown that theNSM has a better performance compared to the EBR however delamination and debonding of FRP sheets fromconcrete is highly probable in both methods and still remains as a limitation Recently special treatments on concrete surface prior to using the FRP sheets in the EBR technique named asExternally Bonded Reinforcement On Grooves EBROG has been introduced in Isfahan University ofTechnology IUT Iran According to this method longitudinal grooves were first caved on the tension face ofthe concrete beam The grooves were then cleaned with compressed air and filled with appropriate epoxy resinand Carbon fiber sheets were adhered to the surface The EBROG method has shown a great promise inresolving the debonding problem Based on some experimental investigations the EBROG method canconsiderably postpone the debonding and in some cases may completely eliminate it The aim of the currentstudy is to introduce another improved strengthening procedure by using the EBROG method while the FRPsheet is in direct contact with carved grooves on the tension face of concrete beam in a wet lay up application This method is named Externally Bonded Reinforcement In Grooves EBRIG For this purpose 36 beamspecimens with the dimensions of 120 140 1000 mm were cast Four distinct strengthening methods i e Externally Bonded Reinforcement EBR Near Surface mounted NSM Externally Bonded Reinforcement OnGrooves EBROG and Externally Bonded Reinforcement In Grooves EBRIG were examined A group ofspecimens were also considered in which FRP laminates were applied to the beams using EBR techniquewithout any surface preparation The beams were then subjected to four point flexural loading Results showedthat EBRIG technique performs as good as EBROG when the section area of FRP sheets are relatively low however it permits for higher failure loads and displacements compared to EBROG method when multi layerFRP sheets are used Thus the method can be used as a reliable technique to significantly reduce or eveneliminate the debonding of FRP sheets from the concrete surface in flexural strengthening of concrete beams Key Words FRP debonding Externally Bonded Reinforcement EBR Near SurfaceMounted NSM Externally Bonded Reinforcement On Grooves EBROG ExternallyBonded Reinforcement In Grooves EBRIG

شاملي، مسعود

روش تركيبي نصب سطحي ورق در داخل شيار ﴿EBRIG ﴾ جهت اتصال ورق هاي FRP به تير بتني

تقويت خمشي , جداشدگي