Many recent researchers in structural engineering have been concerned about new technologies for their successful implementation of computer-integrated structural design systems. As one of the efforts for such systems, this study presents a geometry-based and top-down approaches to computer modeling of building structures. To organize the geometric and topological information obtained, a newly developed geometry-based data abstraction was implemented into network database, which provides a central communication area between applications. Some facilities for intersecting higher-level primitives and splitting them into lower-level entities, and also those for evolving the simple wireframe model to the complex solid model of buildings were developed in order to support top-down structural design processes. This geometry-based top-down approach allows the users to construct computer models of building structures easily and to manage the models at the highest possible level.
Conventional algorithms and newly developed expert systems were also synthesized on the network database. The conventional procedural codes automate the routine design phases such as structural analysis and member design, whereas the rule-based expert systems support designer's decisions at the creative design phases such as preliminary structural system and member design etc. The concepts presented in this paper will contribute to the formulation for the development of automated structural design systems of buildings.