An expert system for the conceptual design of bridges

Abstract

The design of any structure can be said to consist of two stages: the first being the conceptual design stage, in which the overall form of the structure is decided upon. The second stage consists of a more detailed structural analysis, during which calculations are carried out to verify the conceptual design choice and determine component dimensions. Both parts of the design process are of importance, and yet in terms of the research effort expended, the second stage of structural analysis has received far more attention. The probable reason for this emphasis is that the behaviour of structures under load is appropriate to numerical analysis, whereas conceptual design is more subjective, relying heavily on the experience of the engineer, and therefore does not lend itself to formal expression. Bridges are a prime example of the type of structure where conceptual design is of importance, and this paper describes the development of an Expert System for use in the conceptual design of a bridge. The information has been obtained from ‘expert’ engineers, with a wealth of experience in bridge design, and this paper discusses the methods used to elicit the expert knowledge from these engineers. Ultimately, the completed system will provide a source of information about this experience which is as yet unavailable to the young engineer. In addition, the work described has thrown light on the subject of conceptual design itself, an area poorly documented to date. It is shown that the use of an Expert System would provide a representation of the way in which the conceptual design process is carried out, as well as providing a useful advisory facility for the inexperienced designer.