PSI - Issue 13

Jaroslav Odrobiňák et al. / Procedia Structural Integrity 13 (2018) 1947 – 1954 Jaroslav Odrobi ň ák, Jozef Gocál / Structural Integrity Procedia 00 (2018) 000–000

1953

7

Table 2. Results of the certifying study.

Load-carrying capacity Relative decrease of the (comparing to t = 0 year) V stan V sing section area section modulus Load-carrying capacity

Age of bridge t

Corrosion rate r’ corr

Section area A [kNm] 12867 12656 12555 12383 12118 11852 27750 27321 27122 26537 26175 25745 20738 20385 20221 19938 19654 19427 19087

Section modulus W [mm 3 ]x10 -3

Bridge identification

[tons]

[tons]

standard

singular

[year] [mm/year]

A

0

1943.2 1910.9 1894.8 1867.8 1825.9 1783.9 13223.8 13023.8 12928.6 12652.4 12481.0 12276.2 3954.6 3852.7 3805.2 3722.6 3639.5 3572.7 3471.9

25.9 25.2 24.8 24.2 23.3 22.4

38.0 37.0 36.5 35.6 34.3 32.9 15.4 14.7 14.4 13.5 13.0 12.4

1.000 0.984 0.976 0.962 0.942 0.921 1.000 0.985 0.977 0.956 0.943 0.928 1.000 0.983 0.975 0.961 0.948 0.937 0.920

1.000 0.983 0.975 0.961 0.940 0.918 1.000 0.985 0.978 0.957 0.944 0.928 1.000 0.974 0.962 0.941 0.920 0.903 0.878

1.000 0.973 0.959 0.937 0.901 0.866 1.000 0.946 0.920 0.845 0.799 0.744

1.000 0.973 0.959 0.937 0.901 0.866 1.000 0.958 0.939 0.882 0.846 0.804

road

10 20 39 70

main girder

31.73

14.4 m

rolled and welded

100

B

0

8.3 7.9 7.7 7.0 6.7 6.2

local road main girder

10 20 54 75

24.97

34.2 m

composite steel-concrete

100

Z LM71 [-]

Rel. decrease of Z LM71

0

1.205 1.161 1.140 1.105 1.069 1.041 0.998

1.000 0.963 0.946 0.917 0.887 0.864 0.828

C

10 20 40 60 76

railway stringer

22.83

4.9 m

riveted

100

3.3. Discussion From the results of the presented study it can be stated out, that the decrease of cross-section areas of the chosen bridge members as well as their load-carrying capacities corresponds to the increase of the corrosion attack D’ , when after about 15 years it takes a practically linear course. Interestingly, this conclusion applies to each of the three cases examined with different cross-sectional shape and different range of corrosive attack. The relative decrease of load carrying capacity is stronger than decrease of the corresponding cross-section area, which is due to the fact that the bending resistance of the cross-section is reduced by other load effects. This phenomenon emphasizes the importance of monitoring the influence of corrosion on the static safety of the bridge structure. 4. Conclusions The results of experimental measurements of the corrosion losses of structural steel in the test corrosion chamber in the salt spray environment show an almost linear course of corrosion over time. It has been demonstrated the suitability of this test for rapid approximation of especially long-term measurements in less aggressive outdoor environments. However, mapping of corrosion losses and corrosive aggressiveness in the real environment appears to be the most effective in terms of assessing the behavior of metallic materials and their surface treatments. But, even detailed map processing does not take into account local factors resulting from design of structures or their individual elements. Especially in the case of larger structures, such as bridges, the position in construction appears to be one of the decisive factors influencing the origin and progression of corrosion, Křivý et al. (2014).