PSI - Issue 5

Hołowaty J. et al. / Procedia Structural Integrity 5 (2017) 1035 – 1042 Wichtowski and Hołowaty. / Structural Integrity Procedia 00 ( 2017) 000 – 000

1040

6

the Polish bridge standards PN-82/S-10052 for steel bridges and PN-85/S-10030 for bridge loadings as for fatigue verification i.e. under characteristic loads with dynamic factor. In column 3 of Table 1, the nominal stress under bridge permanent loads is given and in column 4 under permanent loads and the code live loading (UIC 71) with dynamic factor. The Polish bridge code for loads has used the UIC rail traffic model since 1982. The stresses were calculated for the primary load situation taking load class with the factor α = 1.21. In colum n 5, the stress values for permanent loads and traffic loads from locomotives with dynamic factors are given. For bridges numbers I to VII, an ET22 electric locomotive was used and for bridge VIII two PT31 steam locomotives. In column 6, the values measured during the load tests in the form of stresses for bridge VIII are given under static and dynamic loading of the bridge using two PT31 steam locomotives with 32D29 tenders. In the final 7th column, the ratio of the stresses  =  ser /  code are given. Of note is that in these bridges the maximum service stresses are from 60 % to 70 % of the code load values.

Table 1. Normal stresses due to characteristic loads in girder sections and stress ratio λ .

λ = σ ser σ code

Stress ( MPa )

Bridge No

Girder scheme and location of joints with cracks

Loading scheme

Permanent load g = 1 1 4 6 . . 3 8 = 1 1 5 7 . . 1 1 = 1 1 5 7 . . 4 0 = 1 1 0 3 . . 3 8 = 1 1 2 4 . . 0 3 = 1 1 2 4 . . 8 7 3

Measured

g + Q code 1 1 1 3 6 6 . . 1 5 1 1 2 3 2 8 . . 1 1 1 1 2 3 3 6 . . 7 6 4

g + Q ser

1)

5 6 8 8 0 . . 4 4 7 8 4 4 . . 4 2 7 7 2 9 . . 4 9 4 6 7 3 . . 0 1 5 6 3 3 . . 9 9 5 6 6 5 . . 8 3

1

2

6

7

0.589

I II

0.609

III IV

0.585

1 8 0 0 8 .8 .3 1 9 1 3 1 .6 .1 1 9 1 9 3 .0 .9

0.583

0.576

V

0.574

= 1 1 4 6. . 8 3 1 1 1 3 6 6 . . 1 5 5 6 1 5. . 5 1

0.532

VI

= 1 1 4 6. . 8 3 = 1 1 7 5. . 1 1

0.618

44.2

27.3

VII

0.624

67.2

42.3

= 24.0 89.8

22.3 3) 28.4 4) 29.6 5)

VIII

62.3 2)

0.694

1) Permanent load + ET21 locomotive 2) Permanent load + 2 steam locomotives Pt31 with 32D29 tenders

3) Static load 2xPt31 + tenders 4) Dynamic load, v = 20 km/h 5) Dynamic load, v = 80 km/h