ECCS - Design Guide Weathering Steel Bridges_Cover

Bridges are an important part of Europe's transport infrastructure and are intended to fulfil numerous, but also different tasks. While some bridges are simply about saving time when transporting people and goods from one side of a valley to the other, today's bridges are becoming longer and longer and connect countries, continents and cultures with each other. Whereas in the early days the focus was purely on economic aspects, nowadays bridges also serve as symbols and landmarks.

In many cases of today's award practice, the type of construction and choice of material isdetermined solely by economic aspects, especially in the case of structures that are intended to provide simple and functional transport from point A to point B. It is precisely in the case of these bridges that we are increasingly finding damages today, sometimes associated with massive long-term effects on traffic. Therefore, the awareness of ensuring the durability of the infrastructure and thus the mobility of people as well as the exchange of goods is coming more to the fore. Corrosion damage is a frequent cause of limited serviceability of bridges. This can be observed across a large number of bridges, regardless of the construction material. The erroneous belief that this problem could be solved by constructing everything in concrete, while at the same time reducing construction costs, has led to the fact that today many concrete bridges have to be replaced well before they reach their calculated service life – often by steel or steel composite superstructures. Corrosion damage in steel components can be permanently prevented. The traditional and still most frequently used method is a multi-layer protective paint system. However, this has the disadvantage that it has to be renewed several times during the life cycle of a bridge. On the other hand, there are three almost maintenance-free alternatives that have become increasingly important in recent years: hot-dip galvanised steel with a greater layer thickness, stainless steel and weathering steel. In terms of circular economy, all three variants have the advantage that they can be fully recycled and thus protect the environment and resources. While hot-dip galvanised steel needs a further additional layer, stainless steel and weathering steel are supplied quasi ex works with integrated corrosion protection without any additional layer. The crucial difference is that weathering steel generates comparable construction costs as a painted steel, while stainless steel is significantly more expensive and its use must be very well justified, e.g. by a very aggressive atmosphere. In most cases, however, weathering steel offers the most economic and environmental advantages. It is almost maintenance-free, if properly designed and constructed, and does not lead to consequential costs or traffic disruption.

At the same time, weathering steel provides similar mechanical properties as usual structural steel. Hence the same codes for design, fabrication and erection apply and no extra effort arises. This document is intended to supplement the well-known standards for design and execution and to serve as a guidance for the use of weathering steel in steel and composite bridge construction. For this purpose, basic background knowledge on weathering steel is given, numerous worked examples are shown, and many recommendations from international experiences have been

This document updates an earlier ECCS document from 2001: The Use of Weathering Steel in Bridges; Publication No. 81 of the European Convention for Constructional Steelwork (ECCS). Since the publication at that time, the Eurocodes have become established throughout Europe and various other standards and national guidelines on weathering steel construction have been updated, in some cases substantially. In addition, extensive new knowledge about the use of weathering steel has been gained through progressive practical application and various research projects. For these reasons, there are significant differences between the current document and the previous publication.

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