Abstract: There is no unified theory and method of structural robustness at present, however, the structural vulnerability analysis can effectively reveal the intrinsic causes of the lack of robustness. Firstly, taking a double-pole structure as an example, the change laws of the well-formedness of joint and nodal displacement under loads were analyzed and compared as the changes of the angle between two bars. It is concluded that the well-formedness of a joint represents the ability to resist loads along any arbitrary direction. Thus, the well-formedness is confirmed to be an evaluation indicator of the configuration of the whole structure and the sub-structure. Secondly, on the basis of clustering criteria, such as well-formedness etc., a structural hierarchical model can be established through a clustering process. Thus, the weakness of the structure could be identified. Furthermore, four kinds of vulnerability failure scenarios are obtained through unzipping process and calculation of indexes of failure scenarios. They are minimum failure scenario, minimum damage demand scenario, total failure scenario and maximum failure scenario. Finally, a computer program is coded to perform above processes with C++ building language and has been applied to the analysis of a planar truss, a planar frame and a reticulated shell. The results show that the vulnerability analysis based on configuration can reflect the weak parts of a structure effectively and identify vulnerable failure scenarios in which structural damage is disproportionate to failure consequences. The above results can provide theoretical foundation for taking measures to reduce the inherent vulnerability of structures.
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