Cyclic Loading Behavior of CFRP-Wrapped Non-Ductile Reinforced Concrete Beam-Column Joints

• Main Author: Zerkane, Ali S. H.
• Format: Others
• Published: PDXScholar 2016
• Subjects: Fiber-reinforced plastics > Joints > Design and construction; Fiber-reinforced plastics > Joints > Testing; Carbon fiber-reinforced plastics; Reinforced concrete construction; Concrete beams; Civil and Environmental Engineering
• Online Access: http://pdxscholar.library.pdx.edu/open_access_etds/3000; http://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=4016&context=open_access_etds

Use of fiber reinforced polymer (FRP) material has been a good solution for many problems in many fields. FRP is available in different types (carbon and glass) and shapes (sheets, rods, and laminates). Civil engineers have used this material to overcome the weakness of concrete members that may have been caused by substandard design or due to changes in the load distribution or to correct the weakness of concrete structures over time specially those subjected to hostile weather conditions. The attachment of FRP material to concrete surfaces to promote the function of the concrete members within the frame system is called Externally Bonded Fiber Reinforced Polymer Systems. Another common way to use the FRP is called Near Surface Mounted (NSM) whereby the material is inserted into the concrete members through grooves within the concrete cover. Concrete beam-column joints designed and constructed before 1970s were characterized by weak column-strong beam. Lack of transverse reinforcement within the joint reign, hence lack of ductility in the joints, and weak concrete could be one of the main reasons that many concrete buildings failed during earthquakes around the world. A technique was used in the present work to compensate for the lack of transverse reinforcement in the beam-column joint by using the carbon fiber reinforced polymer (CFRP) sheets as an Externally Bonded Fiber Reinforced Polymer System in order to retrofit the joint region, and to transfer the failure to the concrete beams. Six specimens in one third scale were designed, constructed, and tested. The proposed retrofitting technique proved to be very effective in improving the behavior of non-ductile beam-column joints, and to change the final mode of failure. The comparison between beam-column joints before and after retrofitting is presented in this study as exhibited by load versus deflection, load versus CFRP strain, energy dissipation, and ductility.