Keywords: Swiss codes SIA 269, maintenance of structures, railway bridges, assessment of existing railway bridges, riveted details, wrought iron, mild steel, fatigue, bridge inspection.

The assessment of existing structures has been significantly improved during recent years. European Codes for the assessment of existing structures are in preparation. For the moment however, a realistic examination of these structures is possible with the Swiss series of Codes 269 published in 2011. For existing riveted railway bridges, the following Swiss Codes are useful: SIA 269:2011 "Existing Structures - Bases" [1], SIA 269/1:2011 "Existing Structures - Actions" [2], SIA 269/3:2011 "Existing Structures - Steel structures" [3].

In this paper, a section relating to the actions for railway bridges is given, namely Chapter 11 of SIA 269/1:2011, where the updated vertical railway actions arising from normal use from railway traffic are introduced. The vertical loads fit with the conditions for constructing wagons, in accordance with the line classification system C3, C4, D3, D4, E4 und E5 of the International Union of Railways (UIC). These actions were adopted first by the European project "Sustainable Bridges" [4] in 2007, but the rules given in the Swiss Codes are more user-friendly.

An important aspect for assessing remaining fatigue life is the choice of a suitable Wöhler curve. For the fatigue strength of riveted constructions in wrought iron and mild steel, during the last thirty years, two important steps forward for the choice of applicable Wöhler curves were given in the work of ORE D154 [5] and Greiner and Taras [6] .

Fatigue cracks in the connections of rail bearers and cross girders do not start at places where you can measure or calculate them. Therefore the importance of bridge inspections is emphasised. As an example a method for how to proceed with the assessment of the connection of a cross girder is given by recommending a finite element model to enable the calculation of the remaining fatigue life at the critical points.

1

SIA 269:2011, "Existing structures - Bases", Schweizerischer Ingenieur- und Architektenverein, Zürich, Switzerland, 2011.

2

SIA 269/1:2011, "Existing structures - Actions", Schweizerischer Ingenieur- und Architektenverein, Zürich, Switzerland, 2011.

3

SIA 269/3:2011, "Existing structures - Steel structures", Schweizerischer Ingenieur- und Architektenverein, Zürich, Switzerland, 2011.

4

EU-Project "Sustainable bridges", Sixth Framework Programme, Guideline for Load Resistance, Assessment of Existing European Railway Bridges, Advice on the use of advanced methods, 2007.

5

ORE Bericht D176(D154), "Statistische Auswertung von Ermüdungsversuchen an Nietverbindungen in Flussstahl", ORE, Utrecht, 1986.

6

R. Greiner, A. Taras, "Development and Application of a Fatigue Class Catalogue for Riveted Bridge Components", Structural Engineering International, 20(1), February 2010.

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