Analysis of Retrofitting Non-Linear Finite Element Of RCC Beam And Column Using Ansys

T. Subramani et al. Int. Journal of Engineering Research and Applications www.ijera.com
ISSN : 2248-9622, Vol. 4, Issue 12( Part 5), December 2014, pp.77-87
www.ijera.com 77 | P a g e
Analysis of Retrofitting Non-Linear Finite Element Of RCC
Beam And Column Using Ansys
T. Subramani1
, S.Krishnan2
, M.S.Saravanan3
, Suboth Thomas4
1
Professor & Dean, Department Of Civil Engineering, VMKV Engineering College, Vinayaka Missions
University, Salem, India.
2
Associate Professor and Head, Department of Mechanical Engineering, Mahendra College of Engineering,
Salem, India.
3
Associate Professor, Department Of Civil Engineering, Annapoorana Engineering College, Salem, Tamilnadu,
India.
4
Professor & Director, Salem School of Architecture, Vinayaka Missions University, Salem, India.
ABSTRACT
Many of the existing reinforced concrete structures throughout the world are in urgent need
of strengthening, repair or reconstruction because of deterioration due to various factors like corrosion,
lack of detailing, failure of bonding between beam-column joints, increase in service loads, etc., leading
to cracking, spalling, loss of strength, deflection, etc., Direct observation of these damaged structures
has shown that damage occurs usually at the beam-column joints, with failure in bending or shear,
depending on geometry and reinforcement distribution type.A nonlinear finite element analysis that is a
simulation technique is used in this work to evaluate the effectiveness of retrofitting technique called
“wrapping technique” for using carbon fibres (FRP) for strengthening of RC beam-column connections
damaged due to various reasons. After carrying out a nonlinear finite element analysis of a reinforced
concrete frame (Controlled Specimen) and reinforced concrete frame where carbon fibres are attached to the
beam column joint portion in different patterns ,the measured response histories of the original and
strengthened specimens are then subsequently compared. It is seen that the strengthened specimens exhibit
significant increase in strength, stiffness, and stability as compared to controlled specimens. It appears
that the proposed simulation technique will have a significant impact in engineering practice in the near future.
KEYWORDS:Analysis, Retrofitting Non-Linear Finite Element, RCC Beam, Column, Ansys
I INTRODUCTION
There is a large need for strengthening
of concrete structures all around the world and
there can be many reasons for strengthening,
increased loads, design and construction faults,
change of structural system and so on. The need
exists in flexure as well as shear. Epoxy plate
bonding with carbon fibre reinforced polymers,
CFRPs has shown to be a competitive for
strengthening of existing concrete structures and
increasing the load bearing capacity. Since the first
structures were formed, whether by nature or by
early human beings, they have plagued by
destruction or detoriation. Detoriation and
destructions are laws of nature that affect even
the most modern of structures. Modern
structures like skyscrapers, bridges are costly to
build and the construction period may sometimes
be disturbing the people and society. So it is of
interest to have durable structures with long
life and low maintenance costs, maintenance is
not only of coats but also a necessity to keep a
structure at a defined performance level. The
definition of performance includes load bearing
capacity, durability, function and aesthetic
appearance. A structure which fulfills all the load
carrying capacities might at the same time not
satisfy durability demands or please the society
demands for aesthetic appearance. Absence of, or
incorrect maintenance will in most cases increase
the speed of degradation process and therefore
lower the performance of the structure. If the
performance level has become too low, then
repair is required to restore the structure to its
original performance. Structures with long life
span, which most of the civil and building
structures should have, will meet changed demands
placed on them from the owners, users, or
surrounding society. A structure wilt satisfactory
load bearing capacity, aesthetic appearance and
Durability might not fulfill the function
demands. To meet a changed demand, a structure
might be upgraded, which furthermore can be a
way to increase life, durability and reliability of
the structure. It is often more complicated to
strengthen an existing structure than erecting a
new one. Concerns must be taken to existing
materials, often in deteriorated condition,
RESEARCH ARTICLE OPEN ACCESS

loads during strengthening and to existing
geometry. In some cases it is also difficult to reach
the areas that need to be strengthened. When
strengthening is to be undertaken all failure
modes must be evaluated. Strengthening a structure
for flexure may lead to a shear failure instead of
giving the desired increased load bearing capacity.
It is to be noted that not only the failure mode
of strengthened material is important. If a
critical member in the structure is strengthened,
another member can be a critical one. Because of
changed stiffness in an undetermined structural
system the whole structure must be investigated.
The strengthening should also be designed with
consideration to minimize the maintenance and
repair needs. Furthermore the existing
documentation of the structure is often very poor
and sometimes even wrong. It might be necessary
to redesign the structure with the probable
former codes that were active when the structure
was built. This can give enough knowledge
about the structural mode of action. The
design of strengthening however must fulfill
requirements in codes today. It is not only the
structural and financial aspects that should form the
basis for decisions of strengthening and
choice of strengthening method, but
environmental and aesthetic aspects must also
be considered. The research carried out here by
the process of Nonlinear finite element analysis
aids us to predict the responses of the beam
column joints through elastic, cracking, and
ultimate load ranges, to design an innovative and
economical technique for retrofitting , to
understand the Behavior of beam – column
joints after retrofitting done by using carbon
fibres, to study the ultimate load carrying
capacity of the beam column joint retrofitted with
CFRP wrapped by different techniques such as
composite wrapping, strip wrapping for beam
only and strip wrapping for both beam and
column, to make suitable recommendations for
practicing engineers.
II ABOUT ANSYS
Finite element analysis as a tool is mainly used
to verify the sections tested because, these sections
being thin walled and having perforations through
out length, their behaviour is quite complicated
when subjected to axial loads. Shell elements
available in ANSYS [1] software provide a good
means to verify the experimental results.ANSYS is
an engineering simulation software (computer-
aided engineering, or CAE). ANSYS was listed on
the NASDAQ stock exchange in 1996. In late 2011,
Investor's Business Daily ranked ANSYS as one of
only six technology businesses worldwide to
receive the highest possible score on its Smart
Select Composite Ratings.
2.1About ANSYS
ANSYS has been recognized as a strong performer
by a number of other sources as well. The
organization reinvests 15 percent of its revenues
each year into research to continually refine the
software.ANSYS offers a comprehensive range of
engineering simulation solution sets providing
access to virtually any field of engineering
simulation that a design process requires. Companies
in a wide variety of industries use ANSYS software.
The tools put a virtual product through a rigorous
testing procedure (such as crashing a car into a brick
wall, or running for several years on a tarmac road)
before it becomes a physical object.
Automotive Toyota Prius HEV aerodynamics
optimization for fuel usage reduction
Red Bull Racing aerodynamics optimization for
faster speed
Aerospace
Parker Aerospace high-performance computing for
faster simulation results
 Astrobotic Technology and Carnegie
Mellon University spacecraft structural
analysis for strength and stiffness
 Terrafugia roadable aircraft for proof-of-
concept testing energy.
 Columbia Power wave energy device
shape optimization to reduce maintenance
costs and breakdowns
 Indar Electric permanent magnet wind
turbine generator optimization for reliable
operation
Electronics
 University of Arizona antenna performance
optimization
 Fujitsu Semiconductor Limited integrated
circuit (IC) design optimization
Consumer products
Dyson bladeless fan airflow performance
optimization
 Speedo FASTSKIN3 Racing System drag
reduction
3. ANSYS Products
Simulation Technology: Structural Mechanics,
Multiphysics, Fluid Dynamics, Explicit Dynamics,
Electromagnetism.
Workflow Technology: ANSYS Workbench
Platform, High-Performance Computing, Geometry
Interfaces, Simulation Process & Data Management.
Virtually every industry now recognizes that a key
strategy for success is to incorporate computer-based
engineering simulation early in the development
process, allowing engineers to refine and validate
designs at a stage where the cost of making changes
is minimal. At ANSYS, we bring clarity and insight
to customers' most complex design challenges

through fast, accurate and reliable simulation. Our
technology enables organizations to predict with
confidence that their products will thrive in the real
world. They trust our software to help ensure
product integrity and drive business success through
innovation.Every product is a promise to live up to
and surpass expectations. By simulating early and
often with ANSYS software, our customers become
faster, more cost-effective and more innovative,
realizing their own product
ANSYS
bonded layers of orthotropic materials. In the
nonlinear analysis, due to bending, different
sandwhich layers will be in different states of
strain. So, a layered approach can be adopted
assuming the sandwhich layer to have constant
strain across its thickness even though the strain
varies in the thickness direction of the whole
lamina.
III.MATERIAL INVESTIGATION
Composites are combinations of two materials
in which one of the materials, called the
reinforcing phase, is in the form of fibres, sheets,
or particles, and is embedded in the other
materials called the matrix phase. The
reinforcing material and the matrix material can
be metal, ceramic, or polymer. Composites are
used because overall properties of the composites
are superior to those of the individual
components. For example: polymer/ceramic
composites have a greater modulus than the
polymer component, but aren't as brittle as
ceramics. The following are some of the reasons
why composites are selected for certain
applications: high strength to weight ratio (low
density high tensile strength), high creep
resistance, high tensile strength at elevated
temperatures, and high toughness. The strength of
the composite depends primarily
on the amount, arrangement
and type of fibre (or particle) reinforcement in the
resin. Typically, the higher the reinforcement
content, the greater the strength. In some cases,
glass fibres are combined with other fibres, such
as carbon or aramid, to create a "hybrid"
composite that combines the properties of more
than one reinforcing material. In
addition, the composite is often formulated with
fillers and additives that change processing or
performance parameters. The fibre is an important
constituent in composites. A great deal of
research and development has been done with the
fibres on the effects in the types, volume fraction,
architecture, and orientations. The fibre generally
occupies 30% - 70% of the matrix volume in the
composites. The fibres can be chopped,
woven, stitched, and/or braided. They are usually
treated with sizing such as starch, gelatin, oil or
wax to improve the bond as well as binders to
improve the handling. The most common types
of fibres used in advanced composites for
structural applications are the fibreglass, aramid,
and carbon. The graphite or carbon fibre is made
from three types of polymer precursors --
polyacrylonitrile (PAN) fibre, rayon fibre, and
pitch. The tensile stress-strain curve is linear to
the point of rupture. Although there are many
carbon fibres available on the open market. They
have lower thermal expansion coefficients than
both the glass and aramid fibres. The carbon fibre
is an anisotropic material, and its transverse
modulus is an order of magnitude less than its
longitudinal modulus. The material has a very
high fatigue and creep resistance. Carbon
fibres have high modulus of elasticity, 200-
800 GPa. The ultimate elongation
is 0.3 – 2.5 % where the lower elongation
corresponds to a higher stiffness and vice-versa.
Carbon fibres do not absorb water and are
resistant to many chemical solutions. They
withstand fatigue excellently, do not stress corrode
and do not show any creep or relaxation, having
less relaxation compared to low relaxation
high tensile prestressing steel strands. Carbon fibre
is electrically conductive and, therefore, might give
galvanic corrosion in direct contact with steel.
Figure below show the carbon fibre, fibre
orientation and stress carried by carbon fibre.

A continuous roll of Carbon fibre sheet, and Close
view of orientation of strands in carbon fibre
Since its tensile strength decreases
with increasing modulus, its strain at rupture
will also be much lower. Because of the material
brittleness at higher modulus, it becomes critical
in joint and connection details, which can have
high stress concentrations. As a r e s u l t o f this
phenomenon, carbon composite laminates are more
effective with adhesive bonding that eliminates
mechanical fasteners.
4. FINITE ELEMENT ANALYSIS
Almost all the structures exhibit a certain
degree of nonlinearity at various load stages.
This may be due to material nonlinearity or
geometric nonlinearity. Geometric nonlinearity is
associated with certain structures where large
deflection may alter the configuration of the
structure and affect the behaviour of the structure on
further loading. The effect of displacement on the
internal forces must be considered in the analysis
of such structures. However, in concrete structures,
the displacements are small compared to the
dimensions of the structure and hence in the
present study geometric nonlinearity is neglected.
Since concrete is a non- homogeneous material and
behaves linearly over a small percentage of its
strength, material non linearity is considered.
Currently, the concrete frames are being
designed based on the analysis considering concrete
to be a linearly elastic, homogeneous and isotropic
continuum or based on yield line theory. This
method of analysis is insufficient to strictly
establish the required safety level and serviceability
requirements, together as required by the design
codes. Hence the behaviour of the concrete frames
needs to be determined through elastic,
inelastic and ultimate load ranges. The finite
element method is the most suitable method for this
analysis. Nonlinear finite element analysis is a
powerful tool in determining the internal stress
strain distribution in concrete structures. With the
aid of nonlinear finite element analysis it is
possible to study the behaviour of composite
layered concrete frames up to the ultimate load
range, which leads to the optimum design of the
concrete frames. The load deformation relationships
can be used to realistically predict the
behaviour of the structures. Nonlinear analysis
gives better knowledge of serviceability and
ultimate strength. The computational time and
solution costs of nonlinear analysis are very
high compared to linear analysis. Hence, the method
should be as efficient as possible and the
numerical technique adopted should reduce the
computational requirements. The finite element
analysis approach is adopted considering the
various material nonlinearities such as stress
strain behaviour of concrete ,cracking of
concrete, aggregate interlock at a crack, dowel
action of the reinforcing steel crossing a crack etc.
Composite layered concrete being a composite
materi(abl) by itself, numerical modeling of this is
still an active area of research. Nonlinear finite
element analysis based on advanced constitutive
models can be used well for the simulation of
composite layered concrete Structures. Computer
simulation is a robust tool for checking the
performance of concrete structures in design and
development. Such simulation can be regarded as
virtual testing and can be used to confirm and
support the structural solutions with complex
details and also serve to find an optimal and cost
effective design solution. Hence, the aim of the
present study is to conduct a finite element analysis
for the nonlinear analysis of composite layered
concrete through elastic, inelastic, cracking and
ultimate load ranges. This chapter describes in
detail the finite element simulation of the
composite layered concrete frames.
A. ELEMENTS USED FOR DISCRETISATION
Element used for discretising
concrete
SOLID65 is used for the 3-D modeling of solids
with or without reinforcing bars (rebar). The
solid is capable of cracking in tension and
crushing in compression. In concrete applications,
for example, the solid capability of the element may
be used to model the concrete while the rebar
capability is available for modeling
reinforcement behavior. Other cases for which
the element is also applicable would be
reinforced composites (such as fiberglass), and
geological materials (such as rock). The element
is defined by eight nodes having three degrees
of freedom at each node: translations in the
nodal x, y, and z directions and we have added
another three degrees of freedom that is
rotations about the nodal x, y, and z axes. Hence
forth the element used has been provided with
totally six degrees of freedom. The concrete
element is similar to the solid 45 (3-D
Structural solid) with the addition of special

cracking and crushing capabilities. The most
important aspect of this element is the treatment
of nonlinear material properties. The concrete is
capable of cracking, crushing, plastic
deformation, and creep. They are also capable
of plastic deformation and creep.
Element used for discretising reinforcing bars
Pipe 16 is a uniaxial element with tension-
compression, torsion, and bending capabilities.
The element has six degrees of freedom at two
nodes: translations in the nodal x, y, and z directions
and rotations about the nodal x, y, and z axes. This
element is based on the 3-D beam element
(BEAM4), and includes simplifications due to its
symmetry and standard pipe geometry. This
element has various special features such as stress
stiffening, large deflection and birth and death of
elements.
Element used for discretising carbon fibres
SHELL63 has both bending and membrane
capabilities. Both in-plane and normal loads are
permitted. The element has six degrees of freedom
at each node: translations in the nodal x, y, and z
directions and rotations about the nodal x, y, and
z-axes. Stress stiffening and large deflection
capabilities are included. A consistent tangent
stiffness matrix option is available for use in large
deflection (finite rotation) analyses. This element
has various special features such as stress stiffening,
large deflection and birth and death of elements.
B. CONSTITUTIVE MODELLING OF
CONCRETE
The modeling of reinforced cement concrete
structures poses a problem of different kind
when compared to a homogeneous material like
steel. This is because of the complexity in the
modeling of concrete. The complexity arises due
to its no homogeneity because of plain concrete
constituents and steel. The complexity is also due
to the different properties in tension and
compression. The macroscopic behaviour of
concrete depends on which the material is
composed of form a very important input for the
formulation of the analytical procedure.
The nonlinear material properties of reinforced
cement concrete can be represented by the
constitutive laws. These laws are discussed in
details in this section. A reasonable assumption
would be to take plain concrete as a
homogeneous mixture in the macroscopic sense
and to consider steel separately as a
homogeneous material effective only in the
direction of the reinforcement. Any model which
considers the nonlinear effects due to the
material properties inclusive of cracking
will be a reasonably good model. With the
rational approach, it is possible to trace the
structural response of the reinforced concrete
structures through out their service load history , by
increasing loads through their elastic, cracking,
inelastic, and ultimate load stages. Since the aim of
the present study is to conduct a finite element
analysis for studying the behaviour of composite
layered reinforced concrete structure, the emphasis
is mainly here for the material modelling of the
composite layered reinforced concrete structure
taking into account the stress strain behaviour of
concrete, tension stiffening and the cracking of
concrete.
C. NONLINEAR STRESS STRAIN
RELATIONSHIP OF CONCRETE
In the theory of reinforced concrete it is
assumed that concrete i s e l a s t i c , i s o t r o p i c ,
homogeneous and that it confirms to Hooke’s
law. Actually none of these assumptions are
strictly true and concrete is not a perfectly elastic
material. Concrete deforms when load is applied,
but this deformation does not follow a strictly
set rule. The deformation depends upon the
magnitude of load, the rate at which the load is
applied, and the elapsed time after which the
observation is made. In other words, the
rheological behaviour of concrete that is the
response of concrete to the applied load is quite
complex.
The Knowledge of the rheological properties of
concrete is necessary to calculate the deflections
of the structures, and design of concrete
members with respect to their sections, quantity
of steel and stress analysis. When the reinforced
concrete is designed by elastic theory it is
assumed that a perfect bond exists between
concrete and steel. The stress in steel is m times
the stress in concrete where m is ration between
modulus of elasticity of steel and concrete, known
as modular ratio. The accuracy of design will
naturally dependent on the value of the modulus
of elasticity of concrete , because the modulus of
elasticity of steel is more or less a definite
quantity.It is further to be noted that concrete
exhibits very peculiar rheological behaviour
because of its being a heterogeneous,
multiphase material whose behaviour is
influenced by the morphology of the gel
structures. The modulus of elasticity of concrete
being so important and at the same time so
complicated, we shall see this aspect in further
more details. The modulus of elasticity is
determined by subjecting a cube or cylinder
specimen to uniaxial compression and by
measuring the deflections through dial gauges fixed
between certain gauge length. Dial gauge

reading divided by the guage length will give
the strain and the load applied divided by the
area of cross section will give the stress. A series
of readings are taken and the stress strain
relationship is established. The modulus of
elasticity can also be determined by subjecting
a concrete beam to bending and then using the
formula for deflection and substituting other
parameters. The modulus of elasticity so found
out from actual loading is called the static
modulus of elasticity. It is seen that even under
short term loading concrete does not behave as an
elastic material. However upto 10% to 15% of the
ultimate strength of concrete, the stress strain
graph is not very much curved and hence can
give more accurate value. For higher stresses the
stress strain relationship will be greatly curved and
as such it will be inaccurate.
In view of the peculiar complex behaviour of the
stress strain relationship , the modulus of elasticity
of concrete is defined in somewhat arbitrary
manner. The modulus of elasticity of concrete is
designated in various ways and they have been
illustrated on the stress strain curve below.
Stress strain curve illustrating the modulus of
elasticity of concrete
The term young’s modulus of elasticity can be
strictly applied only to the straight part of the stress
strain curve. In case of concrete since no part of
the graph is straight, the modulus of elasticity is
found out with reference to the tangent drawn to
the curve at the origin. The modulus found from this
tangent is referred to as initial tangent modulus.
This gives satisfactory results only at lower stress
values. For higher stress values it gives a
misleading picture. Tangent can also be drawn at
any other point in the stress strain curve. The
modulus of elasticity calculated with reference
to this tangent is then called tangent modulus. The
tangent modulus also does not give a realistic value
of the modulus of elasticity for the stress level
much above or much below the point at which the
tangent is drawn. The value of the modulus of
elasticity will be satisfactory only for stress levels
in the vicinity of the point considered. A line can
be drawn connecting a specified point on the stress
strain curve to the origin of the curve. If the
modulus of elasticity is calculated with reference to
the slope of this line, then the modulus of elasticity
is referred as secant modulus. If the modulus of
elasticity is found out with reference to the chord
drawn between two specified points on the stress
strain curve then such values of the modulus of
elasticity is known as chord modulus. The modulus
of elasticity most commonly in practice is the
secant modulus. There is no standard method of
determining the secant modulus. Sometime it is
measured at stresses ranging from 3 to 14Mpa
and sometime the secant drawn to the
point representing a stress level of 15, 25, 33, or
50% of ultimate strength. Since the value of secant
modulus decreases with the increase in stress, the
stress at which the secant modulus has been found
should always be stated. The modulus of elasticity
may be measured in tension, compression, or
shear.The modulus in tension is usually equal to
the modulus in compression. It is interesting to
note that the stress strain relationship of aggregate
alone fairly shows a straight line. Similarly the
stress strain relatioship of cement paste alone also
shows a fairly good straight line. But the stress
strain relationship of concrete which is a combination
of aggregate and cement paste together shows a
cueved relationship. Perehaps this is due to the
development of microcracks in the interphase of the
aggregate and the paste. Because of the failure of
bond at the interface increases at a faster rate than
that of the applied stress, the stress strain curve
continues to bend faster than increase of the stress.
D. STRESS STARIN RELATIONSHIP OF
STEEL
Steel is a ductile material. The ductility of steel
is an unique property in this material. This property
does not exist in any other structural material in
the same manner, as it exists in steel. The
concept of ductility of structural steel forms the
basis for the plastic theory. The structural steel is
capable to withstand large deformations beyond
the elastic limit without fracture. The ductility
property of the structural steel is evident from
the stress strain diagram shown in the figure
below.
Stress strain curve depicting the ductility property of
structural steel
It is seen that the stress strain curve is linear

within the elastic range. Firstly the stresses go on
linearly increasing with respect to the strains up to
the upper yield point. From the upper yield point
the stress in the material drops down without
elongation to the lower yield point. This is followed
by the sudden stretching of the material at
constant stress from the lower yield point up
to the strain hardening. It is seen that the yield
stress is reached at a strain of about 0.11 %. At
the constant stress the material elongates up to a
strain of about 1.5 % . The portion of the stress
strain curve from the lower yield point to the strain
hardening represents the plastic range.
E. INPUT DATA
The input data consists of properties of steel,
concrete and the material used for retrofitting that is
carbon fibres such as Young’s Modulus, Poisson’s
Ratio, Yield Stress, Density. Also, the concrete
specimen’s (in one of the model) and the composite
that is carbon fibre layered concrete specimen’s(in the
retrofitted and the rehabilitated models) face on
which the uniformly distributed force is acting will
be given as an input. The boundary conditions
such as fixity ,to be introduced at the ends of the
columns etc are also to be given.
F. OUTPUT INFORMATION
The output includes stresses, strains, translations,
rotations, reaction forces and moments. Section
forces, moments, and transverse shear forces are
available for elements with displacement degrees
of freedom. The nodal displacements, the support
reactions and the normal stresses σx, σy, and σz
and the shear stresses such as τxy , τyz and τzx as
well as the normal strains such as εx, εy, εz and the
shear strains such as γxy, γyz and γzx are obtained.
The displacement in all the directions that is x,y and
z directions are obtained. And lastly a contour
plot of all the output parameters mentioned above
is obtained.
5. DESIGN AND DETAILS OF THE
RC FRAME
The specimens that is the model frame is
designed following the standards and provisions
of Indian code of practice IS 456: 1958. The
material chosen are concrete compressive strength
Fck = 20 N/mm2 and Fe 415 steel
The specimens were reinforced in the joint region for
bond to increase the strength in the joint region. In
order to make the specimen strong in flexure
an additional steel reinforcement was provided in
the mid section of the beam. The dimensions of the
portal frame are as shown in figure – below :
Details of Portal
frame dimensions
A concrete stub of nominal size pertaining to
the portal frame is designed in order to provide
fixity to the portal frame. The nominal
reinforcement is provided for the bottom
stub portion. A basic requirement in RC structures
is that the steel and surrounding concrete act
together and there should be no slip of the bar
relative to its surrounding concrete. Slippage of
the bar may or may not result in overall failure
of the beam. A beam may continue to carry loads
as long as the bars are anchored at the ends.
The concept of development length and replaces
the old practice of satisfying the permissible
flexure bond stress. The force in any reinforcing
bar must be transmitted to the surrounding concrete
by bond before the bar may be terminated.
A brief review of reinforcement provided for
all the frames are summarized in Table below.

VI. ANALYTICAL RESULTS
Finite element model of the reinforcement
according to the design
Finite element model of the reinforced concrete
frame
A. STRENGTHENING OF BEAM
COLUMN JOINTS BY FULL
WRAPPING TECHNIQUE.
The joint area calculated, which is to be
wrapped fully with carbon fibre is as under :
The deflections in the model after the nonlinear
finite element analysis
The joint area calculated, which is to be
wrapped fully with carbon fibre is as under :the
model after the nonlinear finite element analysis
RC model and the beam column joint area
B. STRENGTHENING OF BEAM
COLUMN JOINTS BY FULL
WRAPPINGTECHNIQUE FOR COLUMN
AND STRIP WRAPPING TECHNIQUE FOR
BEAM.
The meshed finite element model fully wrapped
with carbon fibre
Details of the layout of carbon fibres in the beam and
column region .
The stresses in the model after the nonlinear finite
element analysis

The strains in the model after the nonlinear finite
element analysis
The meshed finite element model fully wrapped
with carbon fibre in the column and strip wrapped
in the beam
element analysis
element analysis
The deflections in the model after the nonlinear finite
element analysis
Comparison between the RC model and the RC model
fully wrapped with carbon fibre in the column and
strip wrapped in the beam
C. STRENGTHENING OF BEAM
COLUMN JOINTS BY STRIP WRAPPING
TECHNIQUE FOR BOTH BEAM AND
COLUMN

Details of the layout of carbon fibres in the
beam and column region .
element analysis
element analysis
The deflections in the model after the nonlinear
finite element analysis
Comparison between the RC model and the RC
model strip wrapped with carbon fibre in both the
beam and the column region.
The meshed finite element model strip wrapped with
carbon fibre in both the beam and the column
region.
VI CONCLUSIONS
The analytical programme confirmed that the
externally bonded Fibre Reinforced polymer (FRP)
using Carbon fibre with a new technique called
STRIP WRAPPING TECHNIQUE is a promising
and a viable solution towards enhancing the strength
and stiffness characteristics of beam- column joints
strengthened by design of bonding in joint zone
subjected to uniformly distributed loads for the
model designed portal frames. The retrofitted and
the rehabilitated portal frames exhibited more
strength than controlled frames.
The analysis of the specimens allowed for an
investigation of several variables, details of
which are described previously. The following
conclusive details have been obtained from the
analytical programme:
o The beam column joints, when are
retrofitted with carbon fibre, using the full wrapping
technique, it is seen that 44.44 % load carrying
capacity is increased as compared to that of the
controlled specimen.
retrofitted with carbon fibre, using the strip wrapping
technique for beam portion only of the beam column
joint,
o 32.3 % load carrying capacity is increased
as compared to that of the controlled specimen.
retrofitted with carbon fibre using the strip wrapping
technique for both beam and column portion of the
beam column joint, 26.9 % load carrying capacity is

increased as compared to that of the controlled
specimen.
o In any case, by providing different
percentages of carbon fibres for retrofitting, it has
been observed that the retrofitted and as well as the
rehabilitated models exhibit much more strength as
compared to that of the controlled specimens.
o From the above conclusions, it is
concluded that depending upon the strength
required for the reinforced concrete frame, the
percentage of carbon fibres, that is to be applied
on to the reinforced concrete frame, can be
varied so as to obtain different increments in
strength.
REFERENCES
[1]. Subramani,T , Athulya Sugathan, “Finite
Element Analysis of Thin Walled- Shell
Structures by ANSYS and LS-DYNA”,
International Journal of Modern Engineering
Research,Vol.2, No.4, pp 1576-1587,2012.
[2]. Subramani.T , Senthil Kumar.R, “Modelling
and Analysis of Hybrid Composite Joint Using
Fem in ANSYS”, International Journal of
Modern Engineering Research, Volume 4,
Issue 6 (Version 1), pp 41- 46, 2014.
[3]. Subramani.T, Manivannan.R, Kavitha.M,
"Crack Identification In Reinforced Concrete
Beams Using Ansys Software" ,International
Journal of Engineering Research and
Applications, Volume. 4, Issue. 6 (Version 6),
pp 133 - 141, 2014.
[4]. Subramani.T, Subramani.M, Prasath.K,"
Analysis Of Three Dimensional Horizontal
Reinforced Concrete Curved Beam Using
Ansys" International Journal of Engineering
Research and Applications, Volume. 4, Issue. 6
(Version 6), pp 156 - 161, 2014.
[5]. A.Prota, A.Nanni, G.Manfredi,
E.Consenza, “ Selective Seismic
Strengthening of RC frames with composites”
, Seventh US National Conference on
Earthquake Engineering, Boston,
Massachussets, July,21-25 , 2002 , Pg : 1-11.

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