*Quality and Fatigue Assessment of Welded Railway Bridge Components by Testing DOI: http://dx.doi.org/10.5772/intechopen.104439*

the butt splice locations in the lower chords of the plate girders are given in columns 5–7 in **Table 2**. Column 8 shows the results of service stresses measured on the welded joints of bridge III located on the Katowice–Tczew coal railway line. The permanent load and the electric locomotive ST-21 (live load) are taken into account. The great similarity of stresses calculated theoretically (column 7) and stresses measured "in situ" on bridge III (column 8) are of note.


#### **Table 2.**

*Bridges, their technical data, and normal stresses in butt welds with cracks as well as behind cover plates.*

Locations of welded butt splices:

The calculations assume the creation of a national set of standards, i.e. Polish bridge standards: PN-85/S-10030 and PN-82/S-10052 for actions and steel bridges, respectively. The characteristic values of the live action effects with dynamic factor Φ are taken into account. The standard load model in the form of the contemporary Eurocode railway traffic model LM 71 for loading class k = +2 is under consideration. The stresses were determined on the butt weld and cover plate axis as well as in the flange plates just behind the ends of the rhombic plates (values in denominators). It is easy to see that the service values of stresses in column 7 are from 60 to 70% of the stress values for the standard loading (LM 71) in column 6. This means that they are also lower than the values of Zrj = Δσ<sup>C</sup> = 79 MPa determined according to **Figure 7**, i.e. the service stresses are lower than the limit value for such joints determined in [3].

Considering the load spectra recommended by the JRC (Joint Research Centre) for railway bridges [1], the above value of loading will be smaller. The authors conducted such analyses and described them in [2, 30].

The load spectrum given in **Figure 10** according to the old British standard BS 153 was established in structural calculations [29–31]. The method allows the service life of bridge structures to be prolonged by as much as three times. The authors recommend this method for the endurance assessment of historical bridges.

**Figure 10.** *Stress ratio frequency.*

In some countries, the results of traffic load measurements have been published, giving the load spectra for analyzing existing bridges [32, 33]. New standards and guides for the testing and assessment of existing bridges have appeared [19, 34–37].
