# Mechanical Properties of Bridge Steel from the Late 19 th Century
## 2 Materials and Methods  
The tests were performed on structural steel taken from a railway bridge which was built in the late 19 th century on the territory of today's Poland. It was one of the bridges situated at the two railway routes--Radom-Tomaszow and Warsaw-Cracow--which are one route on a certain line. The bridge was built to serve one railway track, while there were 3 tracks in total. It was built in order to overcome a terrain obstacle in the form of a dry pit. The bridge was intended for normal rail traffic. This line covered wagon trains, cargo trains as well as rail buses and EMU (Electric Multiple Unit). The rail traffic corresponded to Load Model 71 according to EN 1991-2 [24]. This model represents the static effect of vertical loading due to normal rail traffic. For standard rail traffic (EC Mix), the traffic volume per year may be assessed totally as 25 \(\times\) 10\({}^{6}\) t, due to the fact that there was one track. The bridge from which the steel for tests was taken had a beam structure (Figure 1), which consisted of two single-span steel structural girders made of riveted sheet metal, with an I-beam cross-section. The length of the bridge span was 16.6 m, and the section height of bridge in the middle of the span was 1.71 m.  
Structural girders had an I-beam cross-section and were made of riveted sheet metal and angle bars. Figure 2 shows the cross section of the bridge structure in the centre of its span and the support zone. Its web was made of a 1600 \(\times\) 14 mm metal sheet, while the flanges were made of L100 \(\times\) 100 angle bars, connected using 220 \(\times\) 12 + 300 \(\times\) 12  
Figure 1: View of railway bridge from late 19 th century, from which the tested steel was taken.  
and 220 \(\times\) 16 metal sheets, which were situated at the top and bottom, respectively. The girders had a variable cross-section, because only one metal sheet was used in the support zone per each flange, with the number of metal sheets increasing towards the centre of the span, where 4 metal sheets were used. The load-carrying structure of the bridge was braced using X-shaped transverse beams consisting of L 80 \(\times\) 8 equal-armed angle bars.  
Due to the fact that the bridge was built in 1885 and was in use until 2007, the period of its operation lasted approximately 122 years, which according to the currently applicable requirements of standard EN 1990 [1] significantly exceeds its maximum operational life. Other requirements were to obtain maximal speeds as 110 km/h for wagon trains, rail buses and EMU and 80 km/h for cargo trains. This was impossible due to the poor technical condition of the bridge. In the end it was dismantled because of the structure deterioration, mainly due to advanced corrosion of its main structural elements (Figure 3). This posed a very realistic hazard in the context of its operation.  
Bearing in mind the above, we were interested in establishing the actual strength of the structural material of the railway bridge in question. The scope of undertaken tests included the identification of the main mechanical parameters of bridge steel, such as static and impact strength, and the characterisation of its macrostructure. The tests were  
Figure 3: View of corroded sections of the structure of railway bridge from late 19 th century.  
Figure 2: Mid-span and support-zone cross-section of railway bridge from late 19 th century.  
performed as part of the procedure for the structural assessment of metal structures using acoustic emission, with a focus on steel bridge assessment [25].