:Table of Contents
1) Introduction : ( What is FRP ? ) .
2) Fiber Material Behavior .
3) FRP STRENGTHENING SYSTEMS .
4) Analysis and design .
5) Application requirements for repair and
strengthening works .
Introduction:
What is FRP ?
FRP ( Fiber reinforced polymer ) is a
composite made of high-strength fibers and a
matrix for binding these fibers to fabricate
structural shapes .
Fiber Types
Carbon
Glass
Aramid
Matrix Tyepes :
Epoxies
Esters
FRP systems have significant advantages
over classical structural materials
including:
High – tensile strength .
low weight .
Corrosion resistance .
Ease of application .
Taylor – made capability .
High – life service limit .
:Disadvantages of FRP systems
low – resistance to fire .
No yield plateau .
High – initial cost .
Repair of reinforced and prestressed
concrete elements .
Retrofitting of beams, columns, slabs,
and walls
Carbon
Aramid
Glass
0.000 0.010 0.020 0.030 0.040 0.050 0.060
Steel
FRP STRENGTHENING SYSTEMS
•Loading Specification
•Design Errors Material Specification
•Change of Code
•Drafting Errors
•Assumption Errors
ERRORS IN DESIGN STAGE
•Poor Insufficient compaction
•Construction Inadequate curing time
•Practices
• Poor Workmanship
• Lack of proper supervision
CONSTRUCTION ERRORS
• Overloading -Change of use
• Environmental factors - Concrete deterioration Earthquake/Seismic forces
SERVICE STAGE
Flexural Strengthening
with FRP
Shear Strengthening
with FRP
Axial Strengthening
with FRP
Load versus deflection curves for both control and
strengthened beams.
Part 3
Design For Flexure
Part 2STRENGTHENING
MATERIALS AND SYSTEMSCLASSIFICATION OF
STRENGTHENING WORKS
Part 1
TECHNICAL TERMSPROBABLE CAUSES OF STRUCTURAL DEFECTS
Probable Structural Defects
Overall structural defects
partial or total
collapse of the main structural elements
structural instability,
sliding
differential settlements , and concrete
cracking
Structuralelements defects
cracking, corrosion, excessive deformations,
bucking of columns, loss of concrete cover
Soil problems
Lack of proper structural detailing
The use of defective materials
Construction errors
Lack of maintenance
Modification of configurations, and elements of
the structure
Steel plate bonding .
Section enlargement and external
posttensioning .
Fiber reinforced composites .
Simply supported beam; 35% upgrade in live load
Bonded Steel Plate
0.5 cm bolted plate
110 kg dead load
Placed by lift truck
Member Enlargement
2 #20 rebar, 10 cm grout
1,125 kg dead load
Formed and cured
FRP Sheet
1 layer resin bonded
2.7 kg dead load
Placed by hand
Bond-critical
flexure
tension
torsion
shear
Contact-critical
column
strengthening
DESIGN VARIABLES FOR COMPOSITES TYPE OF FIBER
FIBER VOLUME
ORIENTATION OF FIBER
• 0o, 90o, +45o, -45o
TYPE OF POLYMER (RESIN)
COST
VOLUME OF PRODUCT - MANUFACTURING
METHOD
DESIGN VARIABLES FOR COMPOSITES
PHYSICAL:
• tensile strength
• Compressive strength
• stiffness
• weight, etc.
ENVIRONMENTAL:
• Fire
• UV ( Ultraviolet )
• Corrosion Resistance
1. Design calculations shall be based on the actual
dimensions .
2. Strains are linearly distributed over the cross-
section.
3. The maximum usable compressive strain in the
concrete is 0.003.
4. The tensile strength of concrete is neglected and all
the tensile stresses are resisted by the reinforcing
steel and the FRP.
5. There is no relative slip between external
FRP reinforcement and the concrete.
6. The FRP reinforcement has a linear elastic
stress-strain relationship to failure
d
b
As
Af = n tf wf
cd
-c
h-c
𝜺𝒔
𝜺𝒃𝒊𝜺𝒇𝒆
𝒇𝒔 𝒇𝒔
𝒇𝒇𝒆 = 𝑬𝒇. 𝜺𝒇𝒆/𝜸𝒇
𝟎. 𝟔𝟕𝒇𝒄𝒖 /𝜸𝒄
𝒇𝒇𝒆 = 𝑬𝒇. 𝜺𝒇𝒆/𝜸𝒇
𝜺𝒄𝟎. 𝟔𝟕𝒇𝒄𝒖 /𝜸𝒄
a = 0.8 c
Reinforced
concrete
section
Strain
distribution
Stress
distribution
(non linear for
concrete
stress)
Stress
distribution
(equivalent stress
concrete block )
(1)
(2)
(3)
(4)
Manual application
Strengthened surface
(substrate)
Resin / Adhesive
Fiber
Reinforced
Polymers
(FRP)
Plane and free of any forms of defects.
Free of moisture, chlorides and sulfate ions.
satisfy the necessary requirements that insure the effectiveness of FRP strengthening works.
free of carbonation and the steel reinforcement shall be free of rust.
The resin shall be a suitable material
capable of adhering the FRP laminates to
the concrete surface and satisfying the
specifications and requirements of the
project .
The type of resin depends on the type of
FRP laminates and surface condition.
The two main types of FRP reinforcement
are determined according to the type of
application .
Good quality control should be insured.
Incorrect or bad application will lead to
debonding between FRP and concrete .
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