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Comparative and parametric study of I and box bridge girders with various codes.

INTRODUCTION

Bridge structures are used to carry vehicular load to bypass some obstruction on the path. a bridge may be simply supported on girders or it may be cable strayed. this study focuses on simply supported bridges consisting of a bridge deck, bearings, girders, bent, column and abutments. spans are considered to be straight and with varying length in this study. India has its own code provision regarding the design of I and box bridge girders. so, to improve and meet the international standards specified by AASTHO (STD and LRFD) and EN1991-2, the IRC live loads can be proportioned accordingly. since this codes allow to adjust the loading if the design vehicles are dissimilar to the above code vehicle. it is noted that the vehicular design loads varies with countries. Since it depends on the vehicle characteristics and traffic condition on bridges of various countries. so, this study will offer fundamental data for further growth of standard loading for bridge design in India.

Hatem M. Seliem [5] compared old Egptian code (ECP 201-2003) with the new ECP 201-2012 (based on traffic load on bridges of EN 1991-2) by taking concrete I shaped, box shaped and composite girder stated that box girder yield almost same in both the codes despite the increase in vehicular live loads of ECP 201-2012. the concrete I shaped girder subjected to less total internal forces as compared to ECP 201-2003. This gives an idea to compare two codes and Eurocodes also. Magdy Samaan [11] studied the curved continuous multiple box girder bridges and applied finite element method to evaluate the mode shapes and natural frequency. This experimental investigation along with parametric study gave the variation of fundamental frequency with a variety of parameters. the fundamental frequency decreases by 20% for each span length increment, the torsional mode shapes decreases with the increase in span length, fundamental frequency decreases with bridge curvature and also span to depth ratio increases with fundamental frequency.suniti suparp [8] compared Thai truck loading with American and European codes and gave factor in terms of shear and moment ratios to meet their international standards.supriya madda [6] did parametric study on the dynamics of bridge girder with span length ranging from 15 to 35 m. the IRC Class A loading

gives variation of bending moment and deflection with increase in span length. for larger span greater than 25m bending moment in longitudinal girder increases with superior rate. deflection increases with increase in span and maximum for 3 longitudinal girder and minimum for 6 longitudinal girder. frequency gives the serviceability criterion for bridges such that the fundamental frequency of bridge should not match with that of vehicular frequency. for 4 lane case frequency increases with number of longitudinal girders.

Modelling And Analysis:

The bridge structure is modeled and analyzed using CSI bridges 2015 software. the models are prepared for 2 lane and 4 lane bridge girders. the frame section properties, bearing properties, girder and deck section properties are defined in the components window. the box and I girder section details are given according to its design capacity. foundation springs are assigned for analysis purpose. the loads are assigned according to the different codes for various bridge spans. vehicle class of CLASS A TR, HSn-44,HL-93 and LM1 are loaded over the bridge deck according to IRC6, AASTHO(STD), AASTHO(LRFD) and EN1991-2 respectively. all the external load factors were automatically taken as per the respective code followed. the bridge girder span length ranges from 20 to 60 m for both I and box girder. the moving load analysis is done to receive shear, torsion and bending moments for worst condition. the modal analysis give mode shapes and fundamental frequency for bridge responses. the loads are considered to receive the maximum response from bridge girder. the truck type and their loading are different for different loads. it depends on the transport facility and traffic condition of various countries.

[FIGURE 1 OMITTED]

The analysis consists of static linear analysis for dead loads. The moving load analysis responds on a variety of vehicle class load given under different country codes. A modal analysis is also conducted to calculate the mode shapes and the fundamental frequencies. bearings are kept free in all directions to calculate the mode shapes. all the three analysis has been simultaneously done to come across the torsion, bending moment and shear force of different bridge girder response to a variety of codes. This will help in compiling data for performing comparative study on girder loading by various vehicle load class.

RESULTS AND DISCUSION

The parametric and comparative analysis of I and Box Girder results in bending moment, shear force, torsion and fundamental frequencies from various standards. the values of all the above parameter are given in table no 1 to 6 for I and Box Girder separately. The maximum bending moment and shear force due to LM1 and Class Aloading are for 2 lane and 4 lane I girder respectively. The maximum moment due to LM1 and HL93 are for 2 lane and 4 lane Box girder respectively. LM1 and Class A loading gives maximum shear force for 2 and 4 lane Box girder respectively. Class A shows maximum torsion for both 2 lane and 4 lane I and box girder. it has been noticed that HSn-44 leads to lowest values for shear, moment and torsion in all the cases, except torsion in 2 lane I girder. the bending moment values are nearly similar for both 2 lane HL-93 and Class A I-Girder and box girder span between 10 to 60m. but for 4 lane I-girder bending moment for 20m, Class A and LM1 gives nearby values whereas for 60 m Class A and HL-93 gave closer values. also, for 4 lane Box girder Class A, HL-93 and LM1 loading shows almost similar moment values throughout all the spans. shear force data shows IRC Class A and LM1 loading have closer value at 20 m span in 2lane I-Girder whereas value of LM1 decreases while moving towards 60m in 4 lane I and Box girders. in case of torsion IRC shows maximum value except for 2 lane Box girder in which it shows close value with LM1 at 20 m then increases and again came closer to LM1 value at 60m. a modal analysis produces bridge mode shapes and frequencies due to varying length and lanes. a maximum fundamental frequency of 6.21 is given by 4 lane box girder at 20 m then it gradually decreases, also a minimum fundamental frequency of 0.731 is given by 2, 4 lane I girder at 60m. since vehicle frequency lies in range of 3-5 Hz. hence, 2 and 4 lane I girder with 20m span may give vibration problems because its fundamental frequency lies in that range. also in case of 2 lane box girder with 20 m span and 4 lane box girder with 30,40 m span there may be serviceability problem due to resonance.

For better comparison and to meet the caliber of international standards a ratio of code specified loading against a response due to IRC loading is required. therefore, the ratio of shear force, bending moment and torsion for both 2 lane and 4 lane I and Box girder is generated and a graph is plotted against the varying span length and given in figure 2 to 8. it has been noted that for 2 lane box girder maximum response is given by LM1 at 60 m and for 4 lane it is given by LM1 at 20m. also in case of I girder maximum response is LM1 for both 2 and 4 lane at 20m.Here minimum reaction is given by 4 lane HS-44 for I girder and 2 lane HS-44 for Box girder. so it has been seen that LM1 give maximum response as ratios above 1 and HS-93 shows nearby value to 1 and below 1,whereas HS-44 shows a lesser value always below 1.thus this can be used as an multiplier with LM1, HSn-44,HL-93 to meet their standards. also it provides basic data for further development of Indian code.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

Conclusion:

This study compared the bridge response due to IRC loading against American and European loading standards under different parameters. all the Indian loading were taken from IRC6-2014.The specific load from each code is taken with its dynamic allowances. the analysis shows the bridge effects due to different loading from various codes.This helps in providing comparative idea of maximum and minimum responses by all the three codes against IRC load. the maximum bending moment, shear force and torsion resulted from various international standards with Indian code has been compared and concluded. The bridge reaction for span varying from 10 to 60 m with 2 and 4 lane I and Box girder were analyzed and given in form of shear, moment and torsion ratio. this ratio helps in differentiating the IRC loading with the other standards. also it helps in analyzing the difference in bridge reactions of various codes. The ratio may be used as a multiplier to calibrate Indian standards against the international standards. also it provides the basic data for further development of the code. this study also concentrates on responses due to I and box shaped girders. Thus, given the difference between both of them. the modal analysis provide fundamental frequency which has already been discussed and helps in providing serviceability criteria for bridges.

REFERENCES

[1.] IRC:6-2014. Indian road standards for loading.

[2.] IRC 112-2011. Indian bridge design code.

[3.] AASHTO16-AAC load handbook on LRFD and STD specifications.

[4.] EN 1991-2. European standards for bridge loads.

[5.] "Assessment of vehicular live load and load factors for design of short-span bridges according to the new Egyptian Code" Hatem M. Seliem, Mostafa Eid, Alaa G. Sherif

[6.] "Static Test Analysis of a Bridge Structure in Civil Engineering" Jiamei Zhao a,b,, Tao Liu c, Yuliang Wang.

[7.] "Seismic Response Analysis of Yachi River Super-large Bridge" Wen-xiu Liua, Bing Zhub, Zhang-liang Yuc and Xing Hand

[8.] "Dynamic Analysis of Curved Continuous Multiple-Box Girder Bridges" Magdy Samaan1; John B. Kennedy, F.ASCE2; and Khaled Sennah,

[9.] Use of I-Beam Grillages and Box Girders in High Speed Railway ProjectsMarco Rosignoli

[10.] "Analysis of Bridge Performance under the Combined Effect of Earthquake and Flood-induced Scour" Swagata Banerjee1 and Gautham G. Prasad2

[11.] "A Study on Simple Beam Bridge Responses Due to Thai Truck Loads" Suniti Suparpa, Panuwat Joyklada

[12.] "Finite element analysis of curved steel girders with tubular flanges"Jun Donga,_, Richard Sause

[13.] "Dynamic analysis of T-Beam bridge superstructure " Supriya Madda1, Kalyanshetti M.G

(1) Gaurav verma and (2) Senthil pandian. M

(1) M.Tech, Structural Engineering School of Mechanical and Building Sciences VIT University Chennai,600127

(2) Assistant Professor, School of Mechanical and Building Sciences VIT University Chennai, 600127

Received 27 May 2016; Accepted 28 June 2016; Available 12 July 2016

Address For Correspondence:

Gaurav verma, M.Tech, Structural Engineering School of Mechanical and Building Sciences VIT University Chennai,600127

E-mail: gaurav.verma2014@vit.ac.in
Table 1: maximum bending moments with various span for I girder.

        2 Lane I girder

Span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      3896.14      3690.27      2886.53      4326.79
30      7972.78      7388.2       6237.84      8520.9
40      13013.45     12317.47     10843.07     13716.47
50      19043        18523.7      16687.5      20031.56
60      26204.62     26116.03     23914.6      27656.6

        4 Lane I girder

Span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      4551.02      4204.02      3182.58      4641.3
30      8781.6       8345.6       6844.8       8538.8
40      14070.89     13631.46     11707.69     13438.09
50      20757.82     20168.16     17839.35     19583.87
60      28655.43     28205.6      25542.3      27157.5

Table 2: maximum shear force with various span for I girder.

        2 Lane I girder

Span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      911.35       792.13       635.35       943.81
30      1158.7       1047.32      888.6        1249.08
40      1406.9       1307         1144.6       1440.21
50      1643.16      1561.2       1398.67      1682.4
60      1881.66      1815.4       1652.73      1930.5

        4 Lane I girder

Span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      1031.992     877.4        689.7        1012.7
30      1333.8       1169.4       968.6        1268.61
40      1603.18      1456.56      1245.17      1528.76
50      1850.48      1732.89      1516.37      1777.67
60      2093.6       2006.78      1786.7       2025.6

Table 3: maximum torsion with various span for I girder.

        2 Lane I girder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      167.898      87.918       62.648       127.978
30      220.233      121.183      92.613       175.235
40      271.12       165.72       124.09       228.6
50      324.828      221.098      166.588      297.678
60      377.322      278.062      214.757      364.252

        4 Lane I girder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      185.28       134.019      86.597       166.487
30      235.409      177.64       120.98       203.82
40      267.27       213.26       151.63       221.14
50      293.245      256.444      188.315      250.366
60      335.28       311.93       235.65       288.12

Table 4: maximum bending moments with various span for box girder.

        2 Lane box girder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      5022.6       4561.899     3483.435     5783.419
30      9223.59      9090.14      7504.683     10438.05
40      14730.32     15081.92     12983.16     16503.16
50      28333.66     29124.84     26509.34     30569.71
60      39749.7      41222.39     38060.35     45558.34

        4 Lane boxgirder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      5847.59      5819.38      4549.11      6145.72
30      12167.25     12100.65     10169.21     12075.95
40      20154.2      20292.5      17717.4      19709.87
50      29782.3      30443.08     27234.6      29123.4
60      48888.44     50357.64     46556.74     48198.86

Table 5: maximum shear force with various span for box girder.

        2 Lane boxgirder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      1088.49      925.89       745.52       1180.96
30      1409.61      1248         1061.18      1495.47
40      1709.92      1569.87      1378.55      1809.069
50      2580.4       2434.43      2238.468     2675.92
60      2971.57      2859.66      2661.32      3156.8

        4 Lane boxgirder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      1031.992     877.4        689.7        1012.7
30      1373.5       1187.58      955.4        1346.12
40      1768.1       1578.24      1337.31      1706.7
50      2125.8       1957.4       1708.2       2051.86
60      2462.07      2325.44      2070.38      2385.67

Table 6: maximum torsion with various span for box girder

        2 Lane boxgirder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      621.608      505.923      413.695      598.55
30      864.5        711.725      602.801      814.785
40      1091.85      926.889      810.331      1027.628
50      986.37       827.464      739.328      963.825
60      1103.09      967.464      877.349      1099.133

        4 Lane boxgirder

span    CLASS A      HL-93        HSn-44       LM1
        loading      loading      loading      loading

20      428.352      301.465      206.892      304.762
30      867.925      682.525      582.905      650.271
40      1200.3       1004.3       873.56       911.725
50      1568.92      1386.21      1223.21      1230.26
60      2095.4       1961.289     1775.9       1758.7
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Author:Verma, Gaurav; Pandian M., Senthil
Publication:Advances in Natural and Applied Sciences
Date:Jun 30, 2016
Words:2628
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