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TECHNICAL PAPER

P Load spreader

2 Ø 8 2 legged Ø 6 @ 125 c/c
A

255 175

45
3 Ø 8 1 Ø 8 A' 2 legged Ø 6 @ 200 c/c

100 600 600 600 100
2000
Longitudinal section
Prestressing tendon Non-prestressing tendon Dimensions in mm
200 200 200
40
175
300 255 300 300

Section A-A' Section A-A' Section A-A'
(a) (b) (c)
Figure 1: Longitudinal and cross-sections of the beam: (a) Before failure, (b) After the first rupture of the BFRP tendon, and
(c) After the second rupture of the BFRP tendon

Tension tests on the BFRP bars were conducted in the Multi- curves of the three tested BFRB-PSC beam specimens are
Hazard Protective Structures (MHPS) Laboratory, on three presented at the end for assessment of the flexural response
specimens, S-1, S-2, and S-3, and the experimental results, with the design approach adopted here.
shown in Figure 2, were found in a good agreement with the
details in the datasheet provided by the manufacturer. The 4. FLEXURAL DESIGN PHILOSOPHY FOR
mean tensile strength recorded was 1116 MPa with a coefficient BFRP-PSC BEAMS
of variation of 0.8% from the manufacturer’s provided value
of 1125 MPa. The average elastic modulus was found to The analytical procedure for designing the BFRP-PSC beam
be 50.84 GPa with a variation coefficient of 2.23% from the as well as obtaining the load-deflection relationship following
manufacturer’s provided value of 52 GPa. The average strain at the present design approach include the steps such as: the
rupture was found to be 0.0231 with a variation coefficient of estimation of the prestress losses, stresses under permanent
1.7% from the manufacturer’s provided value of 0.0235. loads, cracking moment, load-carrying capacity, and deflections
The preparation of the BFRB-PSC beam specimens and Tension test on
the experimental setup are shown in Figure 3. Three beam 1200 the BFRP bar
specimens were cast and tested in four-point bending test, in
loading and unloading cycles with 25 kN interval, up to failure. 900
The experimental results, represented by the load-deflection

Table 1: Mechanical properties of concrete and Stress (MPa) 600
BFRP bar
PROPERTIES OF MATERIAL CONCRETE BFRP 300
Compressive strength (MPa) 40 – S-1 S-2 S-3
S-1
0
Tensile strength of BFRP bar (MPa) – 1116 0.0000 0.0075 0.0150 0.0225
Elastic modulus (GPa) 29.93 50.84 Strain
Strain at rupture (%) – 0.0231 Figure 2: Stress-strain curves for three BFRP bar specimens
tested in tension

THE INDIAN CONCRETE JOURNAL | JANUARY 2021 21