The aim of this investigation is firstly to evaluate the different methods used for confining the
reinforced concrete (R.C) columns either internally or externally. Secondly, the effect of
overheating on the performance of confining methods is studied using the computer program
“ANSYS 5.4”. Beside the traditional transverse steel ties, the internal confinement was
satisfied by steel fibers or a cage of expanded metal mesh inside the ties, while external
confinement was achieved by wrapping the studied columns with ferrocement layers or GFRP
sheets. Six R. C columns were prepared, namely, the control column reinforced traditionally
with transverse ties only, two columns containing 1% and 2% steel fibers, one column
reinforced additionally with a cage of expanded metal mesh, two columns wrapped with
either ferrocement laminates or glass fiber reinforced plastics (GFRP). The columns were
tested under axial loads to evaluate the effect of the different confining methods on the
ultimate capacity and ductility. It was found that adding 2% steel fibers or reinforcing the
column with a cage of expanded metal mesh inside the ties gave almost similar results (26%
increase in the ultimate capacity compared with that of the control column). Despite that the
ultimate capacity of the column wrapped with GFRP was the highest among the studied
columns (37% increase in the ultimate capacity), its ductility was the lowest. The parametric
study using ANSYS 5.4 showed that the R.C columns containing steel fibers were less
affected by fire than the other columns. It was also found that the ultimate capacity of R.C
columns wrapped with GFRP was reduced by fire to a high degree (approximately 53%
reduction in the ultimate capacity). |
