The axial load–axial and lateral displacements relationships as
well as the axial concrete stress–axial and lateral strains relationships
were obtained for each tested specimen. Fig. 5 shows the axial
load–axial and lateral displacements relationships for one
specimen of control columns (SC-2), jacketed columns (SJ-0-2)
and strengthened preloaded columns (SJ-60-1 and SJ-80-1) as well
as the strengthened failed column (SJ-100-1). Fig. 6 shows the axial
concrete stress-axial and lateral strains relationships for the same
specimens. It can be observed that the jacketed specimen (SJ-0-2)
reported significant increase in both load carrying capacity and axial
stiffness as compared to the control specimen (SC-2); such increases
are about 33% and 26% respectively. It can be noticed
that the strengthened preloaded column specimens SJ-60-1 and
SJ-80-1 recorded higher load capacity and axial stiffness as compared
to the control SC-2, but lower than those from the jacketed
column specimen SJ-0-2. Strengthening the failed column SJ-100-