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Comparative analysis and design of box girder bridge sub structure with two di
02 septembre 2013
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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 134 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 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, pp. 134-139 © IAEME: www.iaeme.com/ijaret.asp Journal Impact Factor (2013): 5.8376 (Calculated by GISI) www.jifactor.com IJARET © I A E M E
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 135 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%
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 136 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)
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 137 Figure 3 Reinforcement details of Pile for AASHTO and IRC code Figure 4 Reinforcement details of Pile Cap for AASHTO and IRC code
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 138 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
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 139 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” 6. Hussein Yousif Aziz and Jianlin Ma, “Design and analysis of bridge foundation with different codes”, Journal of Civil Engineering and Construction Technology Vol. 2(5), pp. 101-118, May 2011. 7. Priyanka Bhivgade, “Analysis and design of prestressed concrete box Girder Bridge” Civil engineering portal. 8. Young-Ha Park and Chan-Min Park, “Development of Long Span Prestressed Concrete I Girder Bridge by Optimal Design” expressway transportation research institute 08-06. 9. V.N. H EGGADE, R.K. MEHTA & R. P RAKASH,” Design and Construction of Pre- Tensioned Sutlej Bridge in Punjab” 143-158. 10. Hussein Yousif Aziz and Jianlin Ma,“Experimental and Theoretical Static Analysis of High- Speed Railway” The Open Construction and Building Technology Journal,2012, 6, 17-31 11. RICHARD A. MILLER “AASHTO LRFD Bridge Design Specifications of Prestressed Concrete” AASHTO-LRFD Specification, 4th Edition 12. S. Rana & R.Ahsan, “Design of prestressed concrete I-girder bridge superstructure using optimization algorithm”, IABSE-JSCE Joint Conference on Advances in Bridge Engineering- II, August 8-10, 2010. 13. Text Book of “Design of Bridges”, By N. Krishna Raju, Fourth Edition OXFORD & IBH PUBLISHING CO. PVT. LTD. 14. Text Book of “Prestressed Concrete a fundamental Approach”, By Edward G. Nawy, Fifth Edition. 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.