AN OBJECT-ORIENTED ALGORITHM FOR AUTOMATED MODELING OF FRAME STRUCTURES - STIFFNESS MODELING

Structural analysis involves three main phases, namely, (1) modeling, (2) analysis, and (3) results processing. Computer software exists to automate the analysis and results processing phases. However, modeling is still done largely by hand, especially for frame structures. This paper considers automated modeling of frame structures in the context of a computer integrated system for structural engineering design. In this system a structure is described in terms of components and connections, and it is necessary to create an analysis model in terms of nodes, elements, boundary conditions, and so on. It is also necessary to relate the analysis results for the model back to the component-connection description for use in design. In earlier papers the authors have described the overall logic of the modeling process. In order to implement the process the use of an object-oriented programming language is proposed. This paper describes an object-oriented algorithm that can be used as the basis for the implementation. The component-connection description of the structure and the object-oriented paradigm are first summarized. The main objects that comprise an object-oriented modeling system are then described, and the message sequences needed to create a finite element model are described. The scope is limited to the formulation of the structure stiffness matrix. The reader is referred to earlier papers for conceptual details of the modeling process.