IRJET- A Review Article on Study Analysis of T-Beam Bridges by Finite Element Method and Courbon’s Method

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072
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A Review Article on Study Analysis of T-Beam Bridges by Finite Element
Method and Courbon’s Method
Preeti Ban1, Prof. Pooja Pardakhe2
1Student of Master of Engineering in structural Engineering, Jagadambha College of Engineering and Technology
Yavatmal, Maharastra, India
2Assistant Professor at Department of Civil Engineering, Jagadambha College of Engineering and Technology
Yavatmal Maharastra, India
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Abstract — T-beam bridge decks is one of the principal
types of cast-in place concrete decks. It consist of a
concrete slab integral with girders. A T-beam bridge was
analyzed by using I.R.C. loadings as a one dimensional
structure and also T-beam bridge is analysed as a three-
dimensional structure by using finite element plate for the
deck slab and beam elements for the main beam using
software .Both models are subjected to I.R.C. Loadings to
produce maximum bending moment. We are study from
this result the finite element model are lesser than the
results obtained from one dimensional analysis by
Courbon's Method, that means the results obtained from
manual calculations subjected to IRC loadings are
conservative.
Key Words —T-Beam, Finite Element Method,
Courbon’s Method
1. INTRODUCTION
A T-beam used in construction, is a load-bearing
structure of reinforced concrete, wood or metal, with a t-
shaped cross section. The flange (Horizontal Section) or
compression member of the beam in resisting
compressive stresses. The web (vertical section) of the
beam below the compression flange serves to resist
shear stress and to provide greater separation for the
coupled forces of bending
In some respects, the T-beam dates back to the
first time a human formed a bridge with a pier and a
deck. After all, a T-beam is, in one sense, no more than a
pillar with a horizontal bed on top, or, in the case of the
inverted T-beam, on the bottom. The upright portion
carrying the tension of the beam is termed a web or
stem, and the horizontal part that carries the
compression is termed a flange. However, the materials
used have changed over the years but the basic structure
is the same.
2. Lods acting on a Bridge
Various types of loads are considered for design of
bridge structures. These loads and their load
combinations decides the safety of the bridge
construction during its use under all circumstances.
Different design loads acting on bridges are explained
below.
1. Dead load
2. Live load
3. Impact load
4. Wind load
5. Longitudinal forces
6. Centrifugal forces
7. Buoyancy effect
8. Effect of water current
9. Thermal effects
10. Deformation and horizontal effects
11. Erection stresses
12. Seismic loads
2.1 Dead Load
The dead load is nothing but a self-weight of the bridge
elements. The different elements of bridge are deck slab,
wearing coat, railings, parapet, stiffeners and other
utilities. It is the first design load to be calculated in the
design of bridge.
2.2 Live Load
The live load on the bridge, is moving load on the bridge
throughout its length. The moving loads are vehicles,
Pedestrians etc. but it is difficult to select one vehicle or
a group of vehicles to design a safe bridge.
So, IRC recommended some imaginary vehicles as live
loads which will give safe results against the any type of
vehicle moving on the bridge. The vehicle loadings are
categorized in to three types and they are

IRC class AA loading
IRC class A loading
IRC class B loading
IRC Class AA Loading
This type of loading is considered for the design of new
bridge especially heavy loading bridges like bridges on
highways, in cities, industrial areas etc. In class AA
loading generally two types of vehicles considered, and
they are
Tracked type
Wheeled type
IRC Class A Loading
This type of loading is used in the design of all
permanent bridges. It is considered as standard live load
of bridge. When we design a bridge using class AA type
loading, then it must be checked for class A loading also.
IRC Class B Loading
This type of loading is used to design temporary bridges
like Timber Bridge etc. It is considered as light loading.
Both IRC class A and Class B are shown in below figure.
2.3 Impact Loads
The Impact load on bridge is due to sudden loads which
are caused when the vehicle is moving on the bridge.
When the wheel is in movement, the live load will
change periodically from one wheel to another which
results the impact load on bridge.
To consider impact loads on bridges, an impact factor is
used. Impact factor is a multiplying factor which
depends upon many factors such as weight of vehicle,
span of bridge, velocity of vehicle etc. The impact factors
for different IRC loadings are given below.
For IRC Class AA Loading and 70R Loading
TABLE 1 The impact factors for different IRC loadings
Span Vehicle type Vehicle type
Less than 9
meters
Tracked vehicle
25% up to 5m
and linearly
reducing to
10% from 5 m
to 9 m.
Wheeled vehicle 25% up to 9 m
Greater
than 9
meters
Tracked vehicle
(RCC bridge)
10% up to 40
m
Wheeled vehicle
(RCC bridge)
25% up to
12m
Tracked vehicle
(steel bridge)
10% for all
spans
Wheeled vehicle
(steel bridge)
25% up to 23
m

If the length exceeds in any of the above limits, the
impact factor should be considered from the graph given
by IRC which is shown below.
For IRC class A and class B loadings
Impact factor If = A/(B+L)
Where L = span in meters
A and B are constant
TABLE 1 Impact factor
Bridge type A B
RCC 4.5 6.0
Steel 9.0 13.50
Apart from the super structure impact factor is also
considered for substructures
1)For bed blocks, If = 0.5
2)For substructure up to the depth of 3 meters If = 0.5 to
0
3)For substructure greater than 3 m depth If = 0
2.4 Wind Loads
Wind load also an important factor in the bridge design.
For short span bridges, wind load can be negligible. But
for medium span bridges, wind load should be
considered for substructure design. For long span
bridges, wind load is considered in the design of super
structure.
2.5 Longitudinal Forces
The longitudinal forces are caused by braking or
accelerating of vehicle on the bridge. When the vehicle
stops suddenly or accelerates suddenly it induces
longitudinal forces on the bridge structure especially on
the substructure. So, IRC recommends 20% of live load
should be considered as longitudinal force on the
bridges.
2.6 Centrifugal Forces
If bridge is to be built on horizontal curves, then the
movement of vehicle along curves will cause centrifugal
force on to the super structure. Hence, in this case design
should be done for centrifugal forces also.
Centrifugal force can be calculated by C (kN/m) =
(WV2)/(12.7R)
Where
W = live load (kN)
V = Design speed (kmph)
R = Radius of curve (m)
2.7 Buoyancy Effect
Buoyancy effect is considered for substructures of large
bridges submerged under deep water bodies. Is the
depth of submergence is less it can be negligible.
2.8 Forces by Water Current
When the bridge is to be constructed across a river,
some part of the substructure is under submergence of
water. The water current induces horizontal forces on
submerged portion. The forces caused by water currents
are maximum at the top of water level and zero at the
bottom water level or at the bed level.
The pressure by water current is P = KW [V2/2g]
Where P = pressure (kN/m2)
K = constant (value depending upon shape of pier)
W = unit weight of water
V = water current velocity (m/s)
G = acceleration due to gravity (m/s2)
2.9 Thermal Stresses
Thermal stresses are caused due to temperature. When
the temperature is very high or very low they induce
stresses in the bridge elements especially at bearings
and deck joints. These stresses are tensile in nature so,
concrete cannot withstand against this and cracks are
formed.
To resist this, additional steel reinforcement
perpendicular to main reinforcement should be
provided. Expansion joints are also provided.
2.10 Seismic Loads
When the bridge is to be built in seismic zone or
earthquake zone, earthquake loads must be considered.
They induce both vertical and horizontal forces during

earthquake. The amount of forces exerted is mainly
depends on the self-weight of the structure. If weight of
structure is more, larger forces will be exerted.
2.11 Deformation and Horizontal Effects
Deformation stresses are occurred due to change is
material properties either internally or externally. The
change may be creep, shrinkage of concrete etc. similarly
horizontal forces will develop due to temperature
changes, braking of vehicles, earthquakes etc. Hence,
these are also be considered as design loads in bridge
design.
2.12 Erection Stresses
Erection stress are induced by the construction
equipment during the bridge construction. These can be
resisted by providing suitable supports for the members.
3. Analysis of Girders:
A typical Tee beam deck slab generally comprises the
longitudinal girder, continuous deck slab between the
Tee beams and cross girders to provide lateral rigidity to
the bridge deck. The longitudinal girders are spaced at
interval so 2 to 2.5 m and cross girders are provided at 4
to 5 m Intervals. The distribution of live loads among the
longitudinal girders can be estimate by any of the
following rational methods.
 Courbon method
 GuyonMassonet method
 Hendry Jaegar method
3.1 Courbon’s Theory:
In Courbon’s theory, the cross-beams or diaphragms are
assumed to be infinitely stiff. Due to the rigidity of the
deck, a concentrated load, instead of making the nearby
girder or girders deflected, moves down all the girders
the relative magnitude of which depends on the location
of the concentrated load or group of concentrated loads.
In case of a single concentric load or a group of
symmetrical load, the deflection of all the girders
becomes equal but when the loads are placed
eccentrically with respect to the centre line of the deck,
the deflection of all the girders does not remain the same
but the outer girder of the loaded side becomes more
deflected than the next interior girder and so on but the
deflection profile remains in a straight
The behaviour of the deck is similar to a stiff pile-cap
and the method of evaluation of load sharing or load
distribution over the piles may be utilised in the
evaluation of load coming on each girder.
Courbon’s method is valid if the following conditions are
satisfied:
(i) The longitudinal girders are connected by at least
five cross-girders, one at centre, two at ends and two at
one-fourth points.
(ii) The depth of the cross girder is at least 0.75 of the
depth of the longitudinal girders.
(iii) The span-width ratio is greater than 2 as specified in
clause 305.9.1 of IRC: 21-1987. The Author, however,
recommends that to get realistic values, the span-width
ratio shall be greater than 4 as was shown by the Author
in an article published in the Indian Concrete Journal,
August, 1965.The use of Courbon’s method in finding out
the distribution coefficients is illustrated by an example.
It may be mentioned here that although the span-width
ratio of the deck under consideration is not such as to
make the theory valid but just to make, a comparative
study of the results by the other method viz. Morice and
Little’s theory, this is illustrated.
3.2 Finite Element Method
The finite element method is a well known tool for the
solution of complicated structural engineering problems,
as it is capable of accommodating many complexities
in the solution. In this method, the actual continuum is
replaced by an equivalent idealized structure composed
of discrete elements, referred to as finite elements,
connected together at a number of nodes. Thus the finite
element method may be seen to be very general in
application and it is sometimes the only valid form of
analysis for difficult deck problems. The finite element
method is a numerical method with powerful technique
for solution of complicated structural engineering
problems. It is mostly accurately predicted the bridge
ehavior under the truck axle loading. The finite element
method involves subdividing the actual structure into a
suitable number of sub-regions that are called finite
elements. These elements can be in the form of line
elements, two dimensional elements and three-
dimensional elements to represent the structure. The
intersection between the elements is called nodal
points in one dimensional problem where in two and
three-dimensional problems are called nodal lines and
nodal planes respectively. At the nodes, degrees of
freedom (which are usually in the form of the nodal
displacement and or their derivatives, stresses, or
combinations of these) are assigned. Models which
use displacements are called displacement models and

models based on stresses are called force or
equilibrium models, while those based on combinations
of both displacements and stresses are called mixed
models or hybrid models .Displacements are the most
commonly used nodal variables, with most general
purpose programs limiting their nodal degree of
freedom to just displacements. A number of
displacement functions such as polynomials and
trigonometric series can be assumed, especially
polynomials because of the ease and simplification they
provide in the finite element formulation. This method
needs more time and efforts in modeling than the
grillage. The results obtained from the finite element
method depend on the mesh size but by using
optimization of the mesh the results of this method are
considered more accurate than grillage. Fig. 6 below
shows the finite element mesh for the deck slab and also
for three-dimensional model of bridg
Advantages of Finite element Method
 The finite element method has a number of
advantages; they include the ability to Model
irregularly shaped bodies and composed of several
different materials.
 Handle general load condition and unlimited
numbers and kinds of boundary conditions.
 Include dynamic effects.
 Handle nonlinear behaviour existing with large
deformation and nonlinear materials.
Disadvantages of Finite Element Method
 Commercial software packages the required
hardware, which have substantial price reduction, still
require significant investment
 FEM obtains only approximate solutions.
 Stress values may vary by 25% from fine mesh
analysis to average mesh analysis.
4. LITERATURE REVIEW
R. Shreedhar (2012) The object of the paper the
simple span of T-beam bridge was analyzed by use I.R.C.
loadings as a one dimensional structure and same
analyzed as a three- dimensional structure using finite
element plate for the deck slab and beam elements for
the main beam using software STAAD ProV8i. Both
models are subjected to I.R.C. Loadings to produce
maximum bending moment. The results obtained from
the finite element model are lesser than the results
obtained from one dimensional analysis, that means the
results from manual calculations subjected to IRC
loadings are conservative.
Soumya S1, (2015) :- In this study Paper we
study the design of superstructure of a RC T-beam
bridge by using varying spans. The finite element
method is a very common technique for the analysis of
complicated structure. a simple span T-beam bridge was
analyzed by using I.R.C.loadings as a one dimensional
structure and same analyzed as a three- dimensional
structure using finite element software. Both models are
subjected to I.R.C. Loadings to produce maximum
bending moment. The results obtained from the finite
element model are lesser than the results obtained from
Courbon’s method, that means the results obtained are
conservative
Praful N K (2015) In this paper we studied that
bridge is a structure providing passage for a road, a
railway, pedestrians, a canal or a pipeline. . A simple
span T-beam bridge was analyzed by using I.R.C.
loadings as a one dimensional structure using rational
methods and same T-beam bridge is analyzed as a three
dimensional structure using finite element plate for the
deck slab and beam elements for the main beam using
software , three different span of 16m, 20m and 24m
was analyzed. Both FEM and 1D models where subjected
to I.R.C. Loadings to produce maximum bending
moment, Shear force and similarly deflection in
structure was analysed. The results obtained from the
finite element are lesser than the results obtained from
one dimensional analysis, that means the results
obtained from manual calculations subjected to IRC
loadings are conservative.
S. Basilahamed (2018):- In this paper we study
The T beam bridge deck is a structural element
composed of deck slab rigidly integrated with main
longitudinal girders. In structural analysis, the finite
element method is a numerical procedure for modeling
of complex geometry and irregular shapes as easier as
varieties of finite elements are interconnected at
different nodes provides the solution domain of
problem. In this study, a simple span T-beam bridge was
analyzed using courbon’s method by considering IRC
loadings. And the same model is analyzed by finite
element method for both deck slab and T beam integral
with girders using STAAD V8i SS6 software for four
different spans of 25m, 30m, 35m and 40 m. All analysis
is carried out with suitable IRC Vehicular Loadings. Both
FEM and Courbon’s analysis are subjected to IRC class
AA and IRC 70R tracked vehicular loading system in
order to obtain maximum bending moment and shear
force. From analysis it is observed that the results

obtained from courbon’s method are greater than the
results obtained from finite element analysis, this shows
that the rational computations are conservative and
staad values impart reasonable design. The value of
shear force in rational method is less than that of finite
element analysis due to load combinations and
maximum SF occurs in IRC class AA Tracked vehicle.
Conculsion
After the review of previous researches, it
becomes clear that Bending Moment and Shear force
results were analyzed and it was found that the results
obtained from the finite element model are lesser than
the results obtained from courbon’s method, which
means that the results obtained from one of the rational
method i.e. courbon’s method is conservative and from
FEM using staad pro provides reasonable design of
bridge deck & more economical design method for
transverse reinforcement in concrete bridge deck slab is
obtained in Finite element Method.
Reference
[1] Basilahamed Comparative Analysis and Design of T
Beam Bridge Deck by Courbon's Methodand Finite
Element Method JETIR August 2018, Volume 5,
Issue 8
[2] Soumya S1 Comparative Study of Courbon’s Method
and Finite Element Method of RC T–Beam and Deck
Slab Bridge Volume-5, Issue-6, December-2015
Page Number: 105-111 International Journal of
Engineering and Management Research
[3] Praful N K COMPARATIVE ANALYSIS OF T-BEAM
BRIDGE BY RATIONAL METHOD AND STAAD PRO
[Praful, 4(6): June, 2015] ISSN: 2277-9655
INTERNATIONAL JOURNAL OF ENGINEERING
SCIENCES & RESEARCH TECHNOLOGY
[4] R. Shreedhar (2012) Analysis of T-beam Bridge
Using Finite Element Method International Journal
of Engineering and Innovative Technology (IJEIT)
Volume 2, Issue 3, September 2012

IRJET- A Review Article on Study Analysis of T-Beam Bridges by Finite Element Method and Courbon’s Method

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