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TECHNICAL PAPER

DESIGN APPROACH FOR

CONCRETE BEAMS PRESTRESSED

WITH HIGH-STRENGTH BASALT

FIBER-REINFORCED

POLYMER TENDONS ALI ALRAIE*,

VASANT MATSAGAR

Abstract some similar properties as that of the BFRPs. When concrete
is reinforced or prestressed with any of the FRP tendons, it
Use of basalt fiber-reinforced polymer (BFRP) rebars has lately is recommended to design the beam section in flexure as
been introduced as an effective means for replacement of the over-reinforced as per American Concrete Institute (ACI) ,
[1]
conventional steel reinforcement in concrete structures owing because the concrete crushing offers relatively more ductility
to their relatively superior physical and mechanical properties. than the FRP rupture, unlike the case of steel-reinforced and/
In the present study, BFRP-prestressed concrete (BFRP-PSC) or prestressed concrete members in which the failure of steel
beams have been designed, analyzed, and an assessment of the reinforcements is more desirable than the concrete crushing
flexural behavior has been carried out from the experimental for the sake of achieving more ductility. However, it has been
and numerical results. The beam was designed as a partially stated in the Canadian Standard CSA-S806 2002 that for the
[2]
prestressed under-reinforced section with reinforcements FRP-prestressed members, rupturing of the FRP is permissible,
distributed in two layers aiming to have a kind of progressive provided that the structure as a whole contains supplementary
failure, imparting increased nonlinearity. The finite element reinforcement designed to carry the unfactored dead load or
(FE) analysis was carried out in the commercially available has alternative load paths so that the failure of the member
software ABAQUS using the concrete damaged plasticity (CDP) does not lead to a sudden/ progressive collapse of the structure.
®
approach for modeling the concrete, and the numerical results Furthermore, it was stated that if an FRP-prestressed member
were found in a good agreement with the results obtained from is failing in tension due to rupture of the tendons before the
the current design approach. The study introduced an effective ultimate compressive strain (ε cu ) is reached in the concrete, the
design approach for the structural members prestressed using factored moment of resistance (M r ) shall be greater than 1.5M f ,
the BFRP tendons with improved ductility, and thereby provided where 'M f ' is the factored moment . Therefore, finding an
[2]
a solution for the otherwise brittle failure of the under-reinforced alternative design for the ductility issue by partially prestressing
BFRP-prestressed/ reinforced concrete structures. the tendons in multiple layers has been introduced herein, and
Keywords: Basalt fibers, BFRP tendons, Cracking load, Design hence this study is focusing on the flexural behavior of the BFRP-
approach, Flexural strength, Prestressed concrete beam, prestressed concrete beams following the new design approach.
Progressive failure.
2. STATE-OF-THE-ART AND DESIGN
1. INTRODUCTION PHILOSOPHY

Fiber-reinforced polymer (FRP) composites have become the The failure of concrete beams wherein FRP bars are employed
most popular alternative for the corrosion-prone steel over the depends on the design philosophy adopted. While the failure
last few decades. The FRP materials have a high tensile strength, governed by the rupturing of tendons is sudden/ catastrophic,
usually higher than that of the ordinary reinforcing steel, and the failure governed by the concrete crushing has some ductility,
less elastic modulus depending upon the types of fibers and which may not necessarily provide the required ductility.
epoxy matrix. Since basalt fiber-reinforced polymer (BFRP) Comparison of this approach with the conventional reinforced
is relatively a newer FRP material, most of the methods and concrete (RC) design philosophy can be made, wherein concrete
guidelines, developed in the codes/ standards and textbooks crushing is avoided invariably to preclude sudden failure of
for the FRP materials, do not include BFRP directly, even though the RC member without giving any warning. Earlier, a precast
they include glass fiber-reinforced polymer (GFRP), which has American Association of State Highway and Transportation

THE INDIAN CONCRETE JOURNAL | JANUARY 2021 19
*Corresponding author : Ali Alraie, Email: ra3iali90@gmail.com