Evaluating preliminary structural designs in an expert system

In the preliminary structural design of buildings a number of possible schemes are formulated and accessed. These preliminary designs contain little detail, but broadly outline feasible approaches to the solution of the problem. The object is to select a scheme from the different ones produced that best satisfies a variety of criteria. It is a task in which much is unknown and ill-defined, and involves activities and decisions that are heuristic in nature and rely more on experience and judgement than on computation. A knowledge-based expert system for preliminary design has been developed to assist a structural designer in this task. Our system produces realistic designs for numerous different configurations and performs an evaluation of these designs according to user set goals. This paper gives an overview of preliminary design and the approach taken in our system. The acquisition of knowledge and the determination of evaluation features is discussed, and details are presented on the evaluation scheme which uses a decision analysis approach to the solution of problems with multiple objectives.