A General Representation for Assessing the Similarity of Structures

Abstract

One of the key challenges in SHM is obtaining information about the damage condition of a structure in order to detect and diagnose damage when it appears in a healthy structure. For large civil structures, such as bridges, it is simply uneconomical to damage the structure once it has been built in order to obtain the damage case. To this end, a method for assessing the similarity of structures using a new technique called irreducible element modelling is presented. By accurately assessing the similarity between structures, it may be possible to infer the damage state of one structure from the other; the first step is creating a system for assessing the degree of similarity between structures. The irreducible element (IE) model seeks to create a graphical representation of a structure by breaking it down into its constituent parts, described as irreducible elements. In the case of a bridge, these elements could be the deck and the supports. IEs should be well-defined dynamically, e.g. beams, plates and shells. These IEs will form the vertices in the graphical representation, and the edges will represent the joints between each element as well as the boundary conditions for the system. The graphical representation will be attributed with information regarding the geometry and dimensions of these constituent parts, alongside information regarding their material properties. From this representation, the dynamic properties of the structure can be inferred. The IE model also contains information about the boundary conditions and joints within the structure. This paper describes how to construct an IE model for ‘simple’ systems, showing the amount of information that is required to define the model, and how this can be used to create a graphical representation of the structure for comparison purposes.