Abstract:
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.. 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.
