Case-Based Structural Design - Using Weakly Structured Product and Process Information

Doctoral thesis, 2000

Empirical knowledge plays a significant role in the human reasoning process. Previous experiences help in understanding new situations and in finding solutions to new problems. Experience is used when performing different tasks, both those of routine character and those that require specific skill. This is also the case for structural designers. Over 50% of the work done by the designer on a day-to-day basis is routine design that consists of modifying past designs (Moore 1993). That is, most of the design problems that the designer solves have been solved before, in many cases over and over again. In recent years, researchers have started to study if cases (information about specific problem-solving experiences) could be used as a representation of experiential knowledge. Making use of past experience in the form of cases is commonly known as Case-Based Reasoning (CBR). A requirement for Case-Based Design (Case-Based Reasoning applied in design) to be successful is that the design information is computerized. One information type used in structural design that is starting to become computerized is the one in design calculation documents. Such information is weakly structured (which holds for much of the information representing experience) and it contains both product and process information. In this thesis it is shown how the weak structure of this information can be used to subdivide it into components, which in turn makes it possible to apply the object-oriented abstraction principles also to this kind of information. It is also shown how the detailed design process can be represented and how this representation can facilitate automatic acquisition, retrieval of relevant old design information, and adaptation of this information. Two prototypes BridgeBase and ARCADE have been developed, where the principles described above are applied. Using ARCADE, the more general of these two prototypes, it is presented how information in computerized design calculation documents, gathered from real projects, can serve as containers and carriers for both project information and experience. The experience from the two prototypes shows that Case-Based Design can be usable as a tool for structural engineers.