الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The strengthening of existing concrete structures using FRP composites
had spread worldwide due to the advantages offered by these composites
in comparison with other traditional materials. Basalt fiber reinforced
polymer (BFRP) is a newly developed material in this field that is expected
to compete strongly among other types of FRP composites. This research
aimed at studying the flexural behavior of RC columns strengthened with
different techniques using BFRP bars to assess their efficiency for
strengthening RC columns in order to be introduced as an alternative to
other types of FRP bars. Moreover, this study investigates a new type of
strengthening technique named the “hybrid” technique, which is expected
to offer lots of advantages owing to combining two well-known
techniques, FRP jacketing and NSM techniques.
Basalt fibers are inorganic fibers, similar to glass fibers, that are created by
melting basalt rocks. The manufacturing process of basalt fibers consumes
less energy and does not need any other additives in the single production
process, consequently, leading to a low cost of fibers. The initial studies
showed that the basalt fibers have high tensile strength and modulus, better
chemical resistance, extended operating temperature range, and are
considered to be more eco-friendly when compared to E-glass.
Furthermore, basalt-FRP has been proven to have advantages in attaining
the goal of improving the safety and reliability of structural systems when
compared to traditional glass FRP composites. These advantages make
basalt fibers a promising alternative to glass fibers as a reinforcing and
strengthening material.
This study consists of two phases, phase I was aimed at studying the
mechanical properties of the basalt FRP bars. In this phase, several tests
were conducted on the FRP bars to investigate their mechanical properties
to be used later in phase II. Phase II was aimed at investigating the
structural performance of RC columns strengthened with different
techniques using BFRP bars. The variables considered in this phase are the
strengthening effect (unstrengthened and strengthened), the type of the
FRP bars (BFRP and GFRP), the strengthening technique (NSM and
hybrid), and the diameter of the used FRP bars (10 mm and 12 mm). The
test results are discussed and analyzed in terms of cracking, yielding, and
ultimate behavior, in addition to the crack pattern and failure modes.
The test results showed the efficiency of strengthening RC columns with
different techniques using BFRP bars in enhancing the overall flexural
behavior. Moreover, the test results demonstrated the significance of using
BFRP bars compared to the more traditional GFRP bars for strengthening
RC columns. Using the NSM technique in strengthening RC columns can
increase improve the ultimate load capacity and the ductility of the
columns by 30% and 169%, respectively. Using the hybrid technique can
significantly enhance the ultimate load capacity and the ductility of the
columns by 95% and 241%, respectively.