تقويت برشي اتصالات بتن آرمه ي سه بعدي گوشه تحت اثر بار چرخه اي با استفاده از كامپوزيت هاي FRP

چكيده انگليسي :

219 Shear Retrofitting of Corner 3D Reinforced Concrete Beam Column Joints Using FRP Composites Under Reversed Cyclic Loading Mohammadjavad Hajrasouliha mj hajrasouliha@cv iut ac ir May 12 2018 Department of Civil Engineering Isfahan University of Technology 84156 83111 Isfahan IranDavood Mostofinejad dmostofi@cc iut ac irMohammad Navid Moghim moghim@cc iut ac ir Professor Department of Civil Engineering Isfahan Univ of Technology 84156 83111 Isfahan Iran Department Graduate Program Coordinator Assistant Professor Department of Civil Engineering IsfahanUniv of Technology 84156 83111 Isfahan Iran AbstractBeam column joints are fundamental structural components to provide stability to a concrete frame Compared to other types of joint corner joints are more susceptible to failure due to their smaller size andinferior confinement therefore it is necessary to develop efficient techniques for strengthening three dimensional 3D corner deficient joints of reinforced concrete RC structures However most research hasfocused on two dimensional 2D joints due to the complexity of casting and testing 3D ones Moreover theeffect of lateral beams on the confinement of the joint zone has been neglected in most cases Theseshortcomings undermine the applicability of some of the retrofitting configurations proposed so far to real 3Dstructures This study investigates the shear strengthening of non seismic 3D corner joints i e those lackingadequate transverse reinforcement in the joint zone using carbon fiber reinforced polymer CFRP sheets Todelay the debonding of CFRP sheets off the concrete substrate the externally bonded reinforcement ongroove EBROG technique is used and the hysteretic response of 3D corner joints strengthened via theEBROG method is analyzed Nine 3D joint specimens in half scale size were manufactured and tested Thespecimens consisted of one control specimen one standard specimen conforming to code requirements andseven FRP retrofitted specimens with L shaped and X shaped strengthening configurations Results indicatedthat the adopted strengthening configurations prevented the shear failure of the joint Comparison of themaximum loads achieved at a drift ratio of 4 5 revealed that the EBROG technique combined with FRPfans prevented any load reduction up to the test termination Keywords3D Reinforced concrete beam column joints FRP composites Shear strengthening EBROG FRP fans IntroductionFailure of beam column joints under seismic loads induces significantly increased storydrifts which may lead to the overall collapse of the structure Beam column joints therefore play an important role in the stability of RC moment frames Moreover poordesign and reinforcement of non seismically detailed beam column joints i e those notconforming ACI 318 14 ACI Committee 318 2014 requirements and detailing may leadto their shear failure Corner columns in a structure are smaller in size than other columnssince they are designed to carry less gravity loads The minimal lateral beams connected toa corner joint provides inferior confinement for the joint which results in the highervulnerability of corner joints to cyclic loading It therefore seems that efficient retrofittingtechniques need to be developed for proper confinement of corner joints New designcodes e g ACI 318 14 have established sufficient transverse reinforcement requirementsfor beam column joints to resist seismic loads However many built structures do not meetthese new requirements and their poor performance under seismic loads is likely to beexpected Inadequate transverse reinforcement in the joint and poor detailing required forcyclic loading design form major deficiencies in such structures One remedy entertained

حاج رسوليها، محمدجواد

تقويت برشي اتصالات بتن آرمه ي سه بعدي گوشه تحت اثر بار چرخه اي با استفاده از كامپوزيت هاي FRP

اتصال سه بعدي تير- ستون بتن آرمه , كامپوزيت‌هاي FRP , تقويت برشي , نصب خارجي ورق روي شيار