Repair of cracked beams in flexure

Reinforced concrete structures are subjected to many causes of distressthroughout the service time.Generally, beams are the more critical structural element that maysuffer from partial or total collapse as a result of distress action. Repairof distressed reinforced concrete beams have been under study for anumber of years to achieve the best. cheapest. easiest, more executable andmore economical method of repair. The distress causes, the programming ofre pa.iring , the widely used techniques in repair and strengthening ofdefected structures and the common repair and strengthening methods ofreinforced concrete beams with special attention to flexural behaviour arepresented in this thesis.Four main methods of repair were tested in present study to examinethe behaviour and efficiency of the repaired beams in flexure under twoequal concentrated loads. In the first method, a steel plate was glued andbolted to the bottom face of the beam. In the second one, a steel channelwas used instead of the steel plate. In the third method, the steel channel’Was glued to the bottom face of the beam as before but bolted to thebeam flange. In the fourth one, the steel plates glued only but with usingepoxy adhesive mortar dowels instead of the steel bolts. Unlike most of theprevious investigations, the tested beams were loaded to a certainpercentages of the ultimate designed capacity before carrying out therepair process.Sixteen simply supported reinforced concrete half scale T-beams wereloaded, repaired and then reloaded and tested again by means of i-pointloading system. Many variables were considered such as the load levelprior to the repair process, steel plate length and the bolt depth. Veryinteresting results were obtained. Some relations and recommendations whichmay be useful for designers before choosing the technique and carryingout the repair process were introduced.