1) The document compares the design of a box girder bridge substructure according to the AASHTO and IRC codes. 2) It was found that the IRC code requires more reinforcement bars in the pile cap and piles compared to the AASHTO code for the same dimensions. 3) Finite element modeling using ANSYS showed greater displacement under load for the design according to the IRC code compared to AASHTO, indicating IRC provides more safety.

1. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 5, July – August (2013), © IAEME
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COMPARATIVE ANALYSIS AND DESIGN OF BOX GIRDER BRIDGE SUB-
STRUCTURE WITH TWO DIFFERENT CODES
Patil Yashavant S.1
, Prof. Shinde Sangita B.2
1
P.G. Student, Dept. of Structural Engineering, Jawaharlal Nehru Engineering College,
Aurangabad-431003, Maharashtra. India
2
Asst. Professor, Dept. of Structural Engineering, Jawaharlal Nehru Engineering College,
Aurangabad-431003. Maharashtra, India
ABSTRACT
The design of a highway bridge is critically dependent on standards and criteria. Naturally,
the importance of highway bridges in a modern transportation system would imply a set of rigorous
design specifications to ensure the safety, quality and overall cost of the project. This paper discusses
the comparative analysis of two standards namely AASHTO and IRC followed in construction of
bridge superstructures subjected to load of heavy vehicles. To find out optimized Design, variety of
checks and exercise are performed that are presented in this paper. As a result of this exercise it is
found that results of bending moment and stress for self-weight and superimposed weight are same,
but those are different for the moving load consideration, this is due to the fact that IRC codes gives
design for the heavy loading compared to the AASHTO codes.
The results showed the IRC codes are costly because of the number of reinforcement bars in the pile
cap and piles is more than those with AASHTO code with the same dimensions. Displacement
Analysis is carried out using the ANSYS Software of finite elements base modeling, it shows that as
the intensity of displacement increases chances of settlement also increases.
Keywords- Concrete Bridge Pile, Pile Cap, Nodal Displacement, Reinforcement, ANSYS Model
I. INTRODUCTION
For design of Mega Bridge superstructures there are many codes used around the world and
many countries have their own code depending on the natural conditions and the surrounding
environmental factors, such as the effect of earthquakes and heavy snowfall, etc. In the United States,
Bridge Engineers use the code of AASHTO “American Association of State Highway and
Transportation Officials”; this code can be adopted for design of the highway bridges with special
requirements. Similarly, Indian bridge engineers refer to the IRC (Indian Road Congress) standard to
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do the design. However The AASHTO Standard Specification is adopted by many countries as the
generally accepted code for bridge designs.
While designing project two different codes might result in different design as well as cost
implications. Therefore to choose the most appropriate one, it’s important to do comparative analysis
of codes and their resulting design. To prove this hypothesis in this study following two codes are
chosen.
1) AASHTO-LRFD Bridge Design Specifications
2) IRC and IS codes Design Specification
The Two codes will be used to do the analysis of Box Girder. The similarities and differences,
advantages and disadvantages of each code will be investigated.
II. DESIGN DATA
The manual design for the bridge foundation was done according to the data and the
information available from the project site. The parameters used to design the bridge foundation of
Box Girder Bridge are as follows:
1.The length of the girder is 30 m, the weight is 3563.21 kN. Figure 1 shows the cross section of box
girder.
2.Superimposed dead load (the dead loads above the beam) is 18.5 kN/m.
Figure 1 Cross section of Box girder
3.Concrete pier column is 2 m in diameter, and lateral width is 4 m. The drop panel
diameter is 4 m in both sides with top hat thickness of 20 cm. The total height of pier
with the drop panel is 16.7 m. All dimensions and detailed information are shown in Figure 2.
4.Live load from the superstructure is shown in Table 1.
Code Load
IRC 2267.25KN
AASHTO 1084.28KN
Table 1 Live Load Reaction Comparision
The values of live loads in Table 1 have been taken from previous analysis of box girder in Midas
Civil Software. as we observe reaction due to live load is more in IRC than AASHTO.
Following types of loadings are adopted for the analysis of two lane box girder,
As per IRC
Vehicle Load: - Class AA and Class A
Dynamic Allowance: - 33%
As per AASTHO
Vehicle Load: - HL-93TDM, HL-93TRK
Dynamic Allowance: - 33%

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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III. RESULT AND DISCUSSION
As shown in Table 2 that the design with the two codes is different in some parts of the bridge
and similar in the other, the number of steel bars in the IRC codes is more than that of AASHTO
code. That is because, the IRC codes take higher factor of safety when calculating the amount of
reinforcement required, but at the same time, this design can be deemed economically because it
provides the same dimensions of the foundation. Figure 2 show values of the reinforcement area of
bending for pile cap and piles respectively, it can be seen that the reinforcement area of IRC code is
higher than the other codes. Figure 3 shows the full details of pile foundation reinforcements.
Code Pile Cap Pile
IRC 32mm bar at 150mm
spacing
10mm stirrups
at 200mm spacing
29mm bar of 12 Nos.
AASHTO 32mm bar at 200mm
spacing
10mm stirrups
at 300mm spacing
29mm bar of 8 Nos.
Table 2 Reinforcement comparison
Figure 2 Reinforcement Area comparison
As we observer the pile detailing, lateral reinforcement is same for both the piles because diameter of
piles are same. Figure 4 shows the full details of pile cap reinforcements. The 1144KN and 1528KN
load acting on pair of piles, as we go through the reinforcement detail in IRC design required steel is
more than AASHTO.
IV. ANALYSIS WITH ANSYS PROGRAM FOR FINITE ELEMENT MODEL
Another analysis, using the numerical analysis of the ANSYS program of finite
elements to ascertain the values calculated previously manually and found out the design
suitable to withstand the external loads, by calculating the value of vertical displacement and
other parameters relying on the same dimensions calculated from the design and the same
loads applied.
AASHTO IRC
pile reinfocment 5094.401 7314.366
pile cap reinforcment 3893.72 4771
0
1000
2000
3000
4000
5000
6000
7000
8000
ReinfoementArea(mm2)

4. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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Figure 3 Reinforcement details of Pile for AASHTO and IRC code
Figure 4 Reinforcement details of Pile Cap for AASHTO and IRC code

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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Figure 5 Vertical displacement result for AASHTO code in ANSYS
The load applied in the model is the same as that used for the previous design and analysis
which is about 3431.57KN according to the AASHTO code and 4580KN according to IRC code. The
results of the numerical analysis are shown in Figures 10 to 13. The maximum value for
displacement equal to -18 mm for AASHTO and -24 mm for IRC, respectively, the minus sign refers
the direction of the displacement to down, as we observed the nodal analysis, IRC design shows
more displacement and moment values than AASHTO.
Figure 6 Vertical displacement result for IRC code in ANSYS

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V. CONCLUSION
This paper presents comparative analysis of Bridge sub-structure that would help designer
while considering different factors based on code at the beginning of the project. We also showed
how to use ANSYS for the analysis of box girder. It gives result based on finite element modeling,
Displacement shown by nodes are specified in above figures, Box girder shows better resistance to
the torsion of superstructure.
The bearing capacity of the single pile calculated by the AASHTO code is only 75%
of that calculated by the IRC Code which provide high safety to provide the suitable number of
piles by the first Code. Results of bending moment and stress for self-weight and superimposed
weight are same, but those are different for the moving load consideration, because IRC codes gives
design for the heavy loading compared to the AASHTO codes. Area of steel required for AASHTO
is less compared to IRC. Finally based on this comparative study it’s clear that AASHTO code is
more economical than IRC.
REFERENCES
1. IRC: 6- 2000 “Standard specifications and code of practice for road bridges” Indian road
congress.
2. IRC: 18 – 2000 “Design criteria for prestressed concrete road bridges (post – tensioned
concrete)” Indian roads congress.
3. IS: 1343 – 1980 “Code of practice for prestressed concrete” Indian standard.
4. IRC: 21 –2000 “Standard specification and code of practice for road bridges (Plain and
Reinforced)” Indian road congress.
5. AASHTO (2007). “AASHTO-LRFD Bridge Design Specifications”
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different codes”, Journal of Civil Engineering and Construction Technology Vol. 2(5), pp.
101-118, May 2011.
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15. Patil Yashavant S. and Prof.Shinde Sangita B., “Comparative Analysis of Box Girder Bridge
with Two Different Codes”, International Journal of Civil Engineering & Technology
(IJCIET), Volume 4, Issue 3, 2013, pp. 111 - 120, ISSN Print: 0976 – 6308, ISSN Online:
0976 – 6316.