Fibre Reinforced Polymer in Retrofitting
Fibre Reinforced Polymer in Retrofitting
Fibre Reinforced Polymer in Retrofitting
https://doi.org/10.22214/ijraset.2021.39200
International Journal for Research in Applied Science & Engineering Technology (IJRASET)
ISSN: 2321-9653; IC Value: 45.98; SJ Impact Factor: 7.429
Volume 9 Issue XII Dec 2021- Available at www.ijraset.com
Abstract: Retrofitting is the modification of existing structures to make them more resistant to seismic activity, ground motion
etc. Many of the existing reinforced concrete structures throughout the world are in urgent need of rehabilitation, repair or
reconstruction because of deterioration due to various factors like corrosion, lack of detailing, failure of bonding between beam-
column joints etc. Fibre Reinforced Polymer (FRP) composite has been accepted in the construction industry as a promising
substitute for repairing and in incrementing the strength of RCC structures. It stabilizes the current structure of buildings and
making them earthquake resistant. This paper presents a representative overview of the current state of using FRP materials as a
retrofitting technique for the structures not designed to resist seismic action. It summarizes the scopes and uses of FRP materials
in seismic strengthening of RCC structures and masonry retrofitting.
Keywords: Retrofitting, Rehabilitation, Seismic damage, fibre.
I. INTRODUCTION
Fibre reinforced polymer is a composite material which is made up of two entities :a matrix, which is usually made up of
thermosetting resins (such as epoxy and vinylester) and fibres. The function of matrix is to transfer forces between the fibres and
protect the fibres from detrimental effects. The fibres are essential which will give mechanical properties to the materials. There is a
mix of different types of fibre used such as glass, carbon or aramid. The type of fibre frequently controls the properties of FRP. The
FRP is often named with the reinforced fibre, for instance carbon fibre reinforced polymer (CFRP) . The most important property
that differ between the fibre types are stiffness and tensile strain. The strength of these fibres is of the order of 3000Mpa. Their
strength is even higher than that of prestressing steel and stiffness as of aluminium and steel. Fibre does not rust , at least in a same
way as steel. In particular, they are resistant to attack by chlorides which is the most advantage of fibres. Other advantages of fibres
are durability ,lightweight and negligible amount of creep as compared to steel. Fibre reinforced polymer composites are anisotropic
where as steel and aluminium are isotropic. Therefore, there properties are directional, meaning mechanical properties are in the
direction of the fibre placement. These materials have a high ratio of strength to density, exceptional corrosion resistance, and
convenient electrical, magnetic, and thermal properties. However, they are brittle and mechanical property may be affected by the
rate of loading, temperature and environmental conditions. The primary function of fibre reinforcement is to provide the strength
and stiffness in one direction. It replaces metallic materials in many structural applications where load carrying capacity is
important. FRP allows the alignment of the glass fibres of thermoplastics to suit specific design programs. Specifying the orientation
of reinforcing fibres can increase the strength and resistance to deformation of the polymer. Glass reinforced polymers are strongest
and most resistive to deforming forces when the polymers fibres are parallel to the force being exerted, and are weakest when the
fibres are perpendicular. Thus, this ability is at once both an advantage or a limitation depending on the context of use. Weak spots
of perpendicular fibres can be used for natural hinges and connections, but can also lead to material failure when production
processes fail to properly orient the fibres parallel to expected forces. When forces are exerted perpendicular to the orientation of
fibres, the strength and elasticity of the polymer is less than the matrix alone. In cast resin components made of glass reinforced
polymers such as UP and EP, the orientation of fibres can be oriented in two-dimensional and three-dimensional weaves. This
means that when forces are possibly perpendicular to one orientation, they are parallel to another orientation; this eliminates the
potential for weak spots in the polymer. Depending upon type of fibre used fibre reinforced polymer can be classified as:
Carbon Fiber Reinforced Polymers are most commonly used in industrial masonry structure for the Retrofitting of old structures that
already damaged due to earthquakes, chemical reaction, environment effect etc. Since Carbon fiber Reinforced polymers (CFRPs)
are one the stiffest and lightest composite materials so they are much substantial than other conventional materials in many fields of
applications. Norazman et al investigated the purpose Of using CFRP is to improve the tensile strength of reinforced concrete,
replacing steel, totally and he concluded that the main Advantage of using CFRP as reinforcement is to avoid rusting and corrosion
of reinforcement. The use of (CFRP) composite Reinforcement provides a prospective solution like Column wrapping with CFRP
composites, is a popular alternative for improving The seismic resistance of columns. At present CFRP Is being used for structural
repair for damaged structure due to aging and extreme condition. Because of these advantages, carbon fibre finds great application
in many industries such as aerospace, automotive, military and recreational applications.
Fiber glass is a lightweight, strong, and tough material used in different industries due to their excellent properties. Although
Strength properties are lower than carbon fiber and it is less stiff, but material is typically far less brittle and raw materials are much
less expensive. GFRP bars have been used magnificently as a main reinforcement in concrete bridges, parking garages, tunnels, and
Water tanks . FRP can be realistic to strengthen the beams, columns, and slabs of buildings and bridges, Two techniques are
Typically adopted for the strengthening of beams, relating to the strength enhancement anticipated and those are flexural
Strengthening & shear strengthening. In many cases it may be required to provide both strength enhancements. For the flexural
strengthening of a beam, FRP sheets or plates are applied to the tension face of the member. Glass Fibre reinforced polymer is
widely used in electronics, home and furniture, boat and marine, medical and automobile industries.
The modulus of elasticity of the fibres are 70-200 GPa with an elongation of 1.5-5% depending on the quality. Aramid has fracture
energy and is therefore used for helmets and bullet-proof garments. Aramid main advantages are high strength and low weight. Like
graphite, it has a slightly negative axial coefficient of thermal expansion, which means aramid laminates can be made thermally
stable in dimensions. Unlike graphite, it is very resistant to impact and abrasion damage. They are sensitive to moisture and
ultraviolet radiation and therefore not widely used in civil engineering application.
Fig. 24
III. CONCLUSION
FRP proves to be a wonder material as it has many advantageous properties as compared to Traditional/ conventional materials.
However, despite a considerable number of field applications and Laboratory research on FRP, the research results have not yet
been fully getting its place into teaching Curricula. There are not sufficient engineers who are knowledgeable enough to design
structures with Composite materials or to specify them for construction projects. FRP really is still a specialty item in many
Countries. Providing sufficient training on unique features of FRPs so that engineers could design or specify Them in construction
will improve the scenario. There is a need of Government-Industry-Institute Partnership to take advantage of full potential of FRP.
The increase in use of FRP for retrofitting is inevitable Because of its potential. At last but not the least, works of researchers and
authors are hereby duly acknowledged, using which this paper could get this form.
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