We can observe a growing demand for the refurbishment or the retrofitting of the load-bearing structures in numerous historical bridges. Thus their bearings made from either cast iron or steel are finally re-entering the focus of the structural engineers. The absence of reliable data for the structural assessment of these core-elements forms the point of departure for the following thesis, which elaborates three related themes.

In a first step the history of the bearings from their humble beginnings to the present will be outlined in a genealogical perspective. The reasons which led to the development of cast-iron and steel bridge bearings as well as those factors which caused them to be superseded by bearings made from other materials will feed our discussion of both their relative merits and their disadvantages.
Parts two and three will again restrict the focus on cast-iron and steel bridge bearings. They were integral to virtually every major bridge between 1850 and 1950, the main period for this investigation. Since the major advances and developments of bridge bearings from these materials took place in Germany, the following will concentrate on their evolution in the German spoken countries of Central Europe. Achievements in other countries, if pertinent to the development of the bearings, however, will be taken into account.
Based on the findings regarding their evolution a typological categorisation of the bearings will be introduced. Secondly we will analyse the contexts of their technological development as well as the way in which the nascent building supervision authorities influenced these processes.
Finally the thesis will describe the main areas where the bridge bearings made from either cast-iron or steel nowadays are facing problems resulting from their moveable parts. The material for this discussion will be provided by those rules and formulas the engineers arrived at either based on calculations or with the help of experiments to warrant suitable load-carrying capacity and the serviceability of the bearings.

The analysis of these points will be mainly based upon an evaluation of the historical literature tackling questions of the bearings and selected sources from selected archives. A catalogue added to this thesis worked as a tool to organize the body of these sources according to specific criteria relevant for our purposes.

Doctoral thesis committee
Prof. Dr.-Ing. Werner Lorenz
Prof. Dr.-Ing. Karsten Geißler
Dr.-Ing. Karl-Eugen Kurrer

Disputation
25.11.2010

Link to the publication
http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-20692/