ASSESSMENT OF RESIDUAL LIFE OF GIRDERS OF BRIDGE No

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Life = 120 / k1 m = 211 years Remaining Life = 211 – 66 = 145 years c) Traffic density 18 - 12 GMT 96.25 k1 = ------------------------------------------- = 0.734 2.19 x 1.13 x 53 Life = 120 / k1 m = 304 years Remaining Life = 304 – 66 = 238 years 5.1.3 For Light Traffic: a) Traffic density 42 – 27 GMT 96.25 k1 = ------------------------------------------- = 0.745 2.74 x 0.89 x 53 Life = 120 / k1 m = 291 years Remaining Life = 291 – 66 = 225 years b) Traffic density 27 - 18 GMT 96.25 k1 = ------------------------------------------- = 0.663 2.74 x 1.0 x 53 Life = 120 / k1 m = 412 years Remaining Life = 412 – 66 = 346 years c) Traffic density 18 - 12 GMT 96.25 k1 = ------------------------------------------- = 0.587 2.74 x 1.13 x 53 12
Life = 120 / k1 m = 594 years Remaining Life = 594 – 66 = 528 years Calculated Residual Life of girders in different conditions are shown below: S Traffic Type Residual Life in years for Traffic Density .No. 42 – 27 GMT 27 – 18 GMT 18 – 12 GMT 1 Heavy Traffic 22 76 139 2 Medium Traffic 82 145 238 3 Light Traffic 225 412 528 5.2 Assessment of residual life with damage calculation: . It may be used as a more precise alternative to the simplified procedure as described in para.5.1 above. This method involves a calculation based on Miner’s summation rule. S.N. curve developed for limited number of fatigue testing of specimen taken out from the existing girders and stress cycles are computed from the data as shown in para 4.2.4 of this report. The calculation of residual life of the girders based on the loading spectrum of the Ganga bridge for traffic density of 27 GMT, is shown below: Stress range in N/mm 2 Mean Stress Range in N/mm 2 13 No. of cycles per day No. of cycles as per SN curve X 10 6 96.250-86.625 91.4375 32 3.19 67.375-57.750 62.5625 62 18.16 38.500-28.875 33.6875 38 315.06 Damage per Year (D) =∑ (ni/Ni) =[(32/3.19)+(62/18.16)+(38/315.06)]x10 -6 =0.005 Residual Life = 0 .3/D = 60 years 6.0 Observations: It is observed from the method of assessment of residual fatigue life, without damage calculation that residual life of the girders is more conservative as the minimum residual life calculated is 22 years for heavy traffic (42-27GMT) and the maximum residual life is 528 years for light traffic (18-12GMT). However, based on load spectrum as per Indian Rly’s traffic pattern the residual life as per damage calculation method is 60 years for traffic density of 27 GMT. It seems to be more realistic. The residual life, for lighter traffic conditions. By considering the fact that the residual life varies inversely with the traffic density, the relationship between residual life and traffic density can be drawn on log-log
Page 1 and 2: Ministry of Railways Government of
Page 3 and 4: INDEX S.No Contents Page no. 1. Int
Page 5 and 6: 11x 48.5 m spans in bridge No. 75 w
Page 7 and 8: d) The fatigue life of standard spa
Page 9 and 10: slowly before failure, which shows
Page 11: k1 = ------------------------------
Page 15 and 16: 15 Table -1 RU Loading : Annual tra
Page 17 and 18: Year GMT during the GMT Cum. GMT du
Page 19 and 20: Stress range in N per sq mm 1000 10
Page 21 and 22: No. of cycles 70 60 50 40 30 20 10
Page 23 and 24: 1. The Vasai Creek is spanned by br
Page 25 and 26: vii) The girders are having sliding
Page 27 and 28: WEIGHT CALCULATION Calculation shee
Page 29: REFERENCES: 29 Annexure - III 1. Es

ASSESSMENT OF RESIDUAL LIFE OF GIRDERS OF BRIDGE No

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