FLEXURAL BEHAVIOUR OF CONCRETE BEAMS REINFORCED WITH BASALT FRP BAR

The flexural properties of six 150 x 300 x2400 mm concrete beams reinforced with basalt FRP
(BFRP) bars were investigated. The beams were divided into two groups , the first group
consisted of four beams reinforced with only BFRP bars with reinforcement ratio (ρf) ranged
from 3.59 to 8.95 times the balanced ratio (ρfb ) according to ACI 440.1R-06 . The second
group consisted of two hybrid beams reinforced with BFRP and steel bars with ρf 3.59 and 5.38
times ρfb in addition to one steel bar of diameter 10mm and yield strength 360 MPa . The
beams were tested under four-point bending over a clear span of 2200 mm until failure. The test
results of the first group indicated that when ρf increased by 150% , the ultimate deflection was
reduced by 50% and ultimate load capacity was increased by 40% compared with the beam that
had ( ρf = 3.59 ρfb ) . The mode of failure of the first group beams is concrete crushing in the
top compression fiber. The test results of the beams of the second group indicated that adding
steel bar of diameter 10mm to the beam that had two BFRP bars (by steel to BFRP
reinforcement ratio =35%), led to reducing the ultimate deflection by 42 % while the ultimate
load capacity increased by 10%. Moreover , adding steel bar of diameter 10mm to the beam
that had three BFRP bars (by steel to BFRP reinforcement ratio =25%), led to reducing the
ultimate deflection by 30 % while the ultimate load capacity increased by 8% . This shows that
there is a direct relation between steel to BFRP reinforcement ratio and the reduction of
deflection and the effect of adding steel bar is more pronounced on reducing ultimate deflection
than increasing ultimate load capacity and hence enhancing serviceability of the beams