Preservation of Historical metal Bridges: Evaluation of Their Structural Reliability

Historical bridges, even quite recent ones, are precious historical records worthy of study from the point of view of industrial archaeology. Indeed, because of both the high level of scientific and technological knowledge and the variety of structural concepts and details they contain, bridges do offer an important synthesis of the prevailing trends in the civil engineering of their period. In many countries of Europe, as well as in many states of United States, there is a very large heritage of bridges built at the turn of the nineteenth century. There, transport departments have set up systems for cataloguing historical bridges, which are of large interest because of the contribution they make to the landscape. In addition, there is growing interest in the historical analysis of theories and techniques of construction, with particular attention paid to putting intuitions and theories of construction science into practice. Early metal bridges, mostly built in the second half of the nineteenth century and in the first decades of twentieth century, are of special interest because of their close links with the world of science and construction technology in a period of rapid innovation and theoretical research. In Italy, there is growing interest in the historical analysis of theories and techniques of construction, with particular attention paid to putting intuitions and theories of construction science into practice. Early metal bridges, mainly built in the second half of the nineteenth century and in the first decades of the twentieth century, are of special interest because of their close links with the world of science and construction technology in a period of rapid innovation and theoretical development and consolidation. In addition, a large number of metal ancient bridges are still used for roads and railways. The problem of their preservation and rehabilitation is very felt and starts from the need of measuring their structural reliability. For this purpose an expert system to be used for the automatic evaluation of the state of conservation of metal bridges has been developed and here presented. For proceeding with systematic data gathering, it has been necessary to choose a powerful and versatile method for cataloguing the data. Such a method had to be able to facilitate both a general and a more detailed examination of all the structural deficiencies of the elements of iron bridges and offers a system of interconnected data which can be interrelated to give an overall evaluation of the structure. This automatic method allows then for an inventory of metal bridges with the aim of encouraging projects of rehabilitation for the conservation of historically interesting bridges.