Research Description
Basalt fiber-reinforced polymers (BFRP) have recently become a widely used material for
increasing the ultimate load capacity of reinforced concrete (RC) columns and improving their
behavior throughout their entire life. So, an experimental program consisting of 19 large-scale RC
columns of low strength has been prepared to examine the behavior of strengthened RC columns
at all stages of loading. In this program, the columns were divided into two groups. The main
parameters include the strengthening materials (BFRP wrap, BFRP bars, and carbon fiber reinforced polymers (CFRP) wrap), the strengthening techniques (fully or partially wrapping, the
number and direction of layers), the cross-sectional shapes (square, rectangular, and circular),
and the loading types (eccentric and concentric). The confinement of BFRP wraps significantly
improved the service load and the ultimate failure load. The hybrid systems achieved an adequate
level of confinement of the strengthened columns, increased the maximum load by 43.61 %, and
absorbed energy by 477.2 % compared to the control column. BFRP bars used as a near-surface
mounted material improved the behavior of the columns by up to 60 % and 411 % in maximum
load and absorbed energy, respectively. The ACI and ECP codes predicted good estimates for the
stress of columns strengthened with a single layer but underestimated for columns strengthened
with a single layer and BFRP bars. Based upon the existing test data, BFRP-RC is recommended.
Furthermore, this research can support using BFRPs as strengthening materials.
