مطالعه ي آزمايشگاهي رفتار ستون هاي بتن آرمه ي دايره اي تحت بار خارج از محور و تقويت شده با FRP طولي با به كار گيري روش شيارزني

چكيده انگليسي :

Experimental study on behavior of circular columns under eccentric compression strengthened with longitudinal FRP using grooving method Ala Torabian Isfahani a torabian@cv iut ac ir September 20 2014 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Persian Supervisor Dr Davood Mostofinejad Prof Email address dmostofi@cc iut ac ir Abstract Today the application of fiber reinforced polymer FRP composites has been successfully promoted for strengthening or repairing of structural members Columns are the basic members in a structure that transfer the axial load with or without bending moment So strengthening these members by FRP composites and developing new methods in order to improve their efficiency is very important One of the methods for strengthening reinforced concrete RC columns with FRP composites is using FRP jackets around the columns The FRP jackets are used mainly in a condition that all or most of the fibers of composite are perpendicular to the column axis and in hoop direction to provide confinement However the axial compressive strength of columns can be increased by using FRP composite with longitudinal fibers where the fiber sheets contribute by resisting compression directly Buckling of FRP composite causes inappropriate performance of composite under compressive stresses In longitudinally strengthened columns with FRP buckling of FRP composite causes debonding of FRP from concrete surface On the other hand researches have shown that the newly developed grooving method as alternative to surface preparation can postpone or in some cases eliminate debonding of FRP sheet from the surface of the concrete beams and columns Most of the columns in a structure are under axial flexural loading so study the behavior of columns under eccentric loading seems to be necessary In a column strengthened with longitudinal FRP composites under eccentric loading some of the composites are under tension stresses and because of their high tension resistance increase the strength of the columns On the other hand some of the composites are under compression stresses in this case using grooving method postpones buckling of these composites and they can play an effective role in increasing the strength of the column too So in this research the grooving method is used in the specimens that are strengthened with longitudinal FRP composites in order to study the effect of grooving method in postponing the buckling and debonding the FRP sheets from concrete surface and consequently increasing the strength of specimens In addition because of the importance of ductility in structural members such as columns the ductility of the specimens has been investigated in this research To perform the study 35 cylindrical reinforced concrete specimens with 150 mm diameter and 500 mm height were tested experimentally under compression loading with eccentricity of zero 30 60 and 90 mm and under 4 point flexural bending In this study the conventional externally bonded reinforcement EBR and the grooving method by externally bonded reinforcement on grooves EBROG technique was utilized for installing the FRP sheets with longitudinal fibers Experimental results showed that using the grooving method by EBROG technique increases the load carrying capacity of columns with longitudinal composite and by increasing the load eccentricity the effect of longitudinal composites increased In this case the compression strength of specimens strengthened with longitudinal composites using EBROG technique under zero 30 60 and 90 mm eccentricity of loading and under 4 point flexural bending were respectively increased 8 3 12 2 25 8 36 and 53 3 compared with the unconfined specimens Also according to the results in all kinds of loading grooving method is more effective in increasing the load capacity compared with EBR method In addition the results of studying about ductility showed that longitudinal composites

ترابيان اصفهاني، آلاء

مطالعه ي آزمايشگاهي رفتار ستون هاي بتن آرمه ي دايره اي تحت بار خارج از محور و تقويت شده با FRP طولي با به كار گيري روش شيارزني

ظرفيت باربري , كامپوزيت FRP با الياف طولي , كمانش , بار با خروج از مركزيت , بارگذاري خمش چهار نقطه اي