Practical Residual Force Decomposition Method for Damage Identification of Existing Reticulated Shells

The non-destructive damage identification approaches for existing structures become more of a concern due to safety requirements. However, the application of damage identification method is still limited for complex spatial structures. In this paper, a practical residual force decomposition (RFD) method is proposed to identify damaged members in existing reticulated shell structures. A parameterized model is built by taking the stiffness reduction into consideration. In the proposed RFD method, the significant damage can be recognized corresponding to the changes of the observed eigenvector of the reticulated shells, and the eigenvector changes can be easily transferred to a set of multivariate linear equations to locate the members with significant stiffness reduction. The inputs of the equations are discussed including the additional constraints and the selection of effective modes. According to the different proportion of the numbers of members and joints, three situations of the solution are discussed. Especially when the solution is not unique, the importance coefficients of structural members are introduced as additional constraints through Ritz vector sensitivity analysis and application of the Modal Assurance Criterion. Two illustrative examples including a single-layer Kiewitt-6 reticulated shell and a structural model of international convention center are adopted to demonstrate the effectiveness of the approach. The results show that the proposed method can yield a suitable damage identification.