8. CONCLUSIONS
The premature debonding, which generally occurs in the externally
bonded reinforcement (EBR) technique, was avoided. In the
majority of the strengthened columns some laminate strips of the
CFRP reached tensile strain values close to the ultimate rupture
strain of the CFRP. Some CFRP laminate strips have even failed at
the failure crack of the concrete column. The results indicate that
the strengthening technique proposed by the near surface mounted
(NSM) technique is promising for increasing the load-carrying
capacity of concrete columns failing in bending.
For eccentrically loaded columns, the failure of the unconfined
columns was marked by the crushing of the concrete on the
compression side of the specimen. For the vertical force, 650 kN
was an indication of the reinforcement’s buckling until the concrete
was completely crushed. The observed behavior of the confined
columns was similar to the unconfined columns up to the peak load
of the unconfined columns. Increases in the lateral deflection of the
confined columns resulted in the concrete failing in compression
and rupturing the FRP confining jacket at approximately mid-height.
The deflected shape of the columns at peak load was symmetrical,
and there was no local buckling in the columns.