A Digital Method for Redundant Structural Analysis

Summary A digital method of structural analysis is developed using equivalent electrical circuit analogies in the systemization of the digital computer program. This method is shown to possess particular advantages in the analysis of redundant structural systems, in that the redundancies need not be determined in order to form a statically determinate system. The method is com­ pletely independent of such redundancies. In addition, all of the procedures except the development of the equivalent electrical analogy may be carried out in a simple, routine manner with very little prior experience in the method. HE METHOD of structural analysis presented here involves a formalization of the digital computation in terms of an equivalent electrical circuit representa­ tion of the structural system. This method of electri­ cal circuit representation is familiar to the users of the direct analog computer (Network Analyzer), and is detailed in the references. In the usual context, the structural system is expressed in terms of simple structural elements which are in turn represented by equivalent electrical networks. These networks are then used as building blocks in constructing an electri­ cal model of the structural system. At this point, the electrical model is implemented by means of the Net­ work Analyzer, and the analysis is conducted using the electrical model in much the same way an actual struc­ tural model would be used. In the present method, it is proposed that the electri­ cal circuit representation be developed as though for use on a Network Analyzer, and that this representa­ tion be used to facilitate the systemization of the digital computer program. In a sense, this involves the use of a digital computer as a Network Analyzer simulator. At this point it may be well to direct a few remarks to the structural engineer, who may very likely be thoroughly repelled by any suggestion of expressing a structural problem in terms of an electrical circuit. However, the electrical concepts involved are extremely basic and are surely familiar to engineers of all dis­ ciplines. Furthermore, the usual approach (even for those with electrical backgrounds) is to interpret the electrical circuits largely in structural terms, using elec­ trical concepts only where they contribute to the sim­ plicity and understanding of the system.