ASSESSMENT OF RESIDUAL LIFE OF GIRDERS OF BRIDGE No

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Since the residual life calculations as per Miner’s summation rule are based on the damage caused per day by the present day traffic and fatigue test conducted on the specimen which have undergone different load cycles in the past, hence the traffic passed in the past will not affect the residual life calculations. The residual life calculations in this report for this methodology are based on annual density of 27 GMT and hence, the traffic density increases/decrease in future, the residual life will decrease/increase on prorata basis and will effect the calculations. The details of traffic passed in GMT on the bridge during 1950-51 to 1995-96 is shown in table-3, fig.4 & 4a. On perusal of the table and figures , it is seen that the traffic density which was 9.95 GMT in the year 1950-51, increases to 27.15 GMT in the year 1992-93, the year in which the bridge was abandoned. However, the maximum traffic density prior to 1976-77 was about 18 GMT and increases thereafter up to about 27 GMT. Speed of the train also affect the residual life of the girders, hence for calculation of maximum stress likely to be observed on the girders, the impact factor has also been considered. 5 ESTIMATION OF RESIDUAL LIFE: 5.1 Assessment of residual life without Damage Calculation: Following values of different parameters are considered for estimation of residual life. i) detailed class considered = D (from table 17 of code) ii) Maximum stress range ( σT ) = 96.25 N/mm 2 (calculated) iii) Constant amplitude stress (σ0) = 53 N/mm 2 (from table 8 of code) iv) m = 3 (from table 8 of code) v) k 2 = 1.0 by considering one stress range only vi) k 3 = 1.92 (Heavy traffic) from table 4 of code = 2.19 (Medium traffic)from table 4 of code = 2.74 (Light traffic) “ “ vii) k 4 = 0.89 (42 to 27 GMT) from table 5 of code = 1.0 (27 to 18 GMT) “ “ = 1.13 (18 to 12 GMT) “ “ vii) k 5 = 1.0 (for single lane loading) from table 6 of the code Value of design life factor (k1) is calculated by the formula σ T k 1 = ------------------------------------------- k 2 . k 3 . k 4 . k 5 . σ0 5.1.1 For Heavy Traffic: a) Traffic density 42 – 27 GMT 96.25 10
k1 = ------------------------------------------- = 1.063 1.92 x 0.89 x 53 Life = 120 / k1 m+2 = 88 years Remaining Life = 88 – 66 = 22 years b) Traffic density 27 - 18 GMT 96.25 k1 = ------------------------------------------- = 0.946 1.92 x 1.0 x 53 Life = 120 / k1 m = 142 years Remaining Life = 142 – 66 = 76 years c) Traffic density 18 - 12 GMT 96.25 k1 = ------------------------------------------- = 0.837 1.92 x 1.13 x 53 Life = 120 / k1 m = 205 years Remaining Life = 205 – 66 = 139 years 5.1.2 For Medium Traffic: a) Traffic density 42 – 27 GMT 96.25 k1 = ------------------------------------------- = 0.932 2.19 x 0.89 x 53 Life = 120 / k1 m = 148 years Remaining Life = 148 – 66 = 82 years b) Traffic density 27 - 18 GMT 96.25 k1 = ------------------------------------------- = 0.829 2.19 x 1.0 x 53 11
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: slowly before failure, which shows
Page 13 and 14: Life = 120 / k1 m = 594 years Remai
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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