Measuring full static displacements of cable domes based only on limited tested locations

Abstract

The existing cable domes are normally faced with the possible deterioration of the structural stiffness which is caused by random member damages and pretension deviations. The static testing method can be potentially used in monitoring the structural stiffness, in which the tested locations are normally limited. To improve the testing efficiency and decrease the testing cost, a method to expand the limited static displacements is proposed. Based on the eigen-decomposition of the structural stiffness, the unified expression of the static displacements under a specific load is derived, in which the static displacements are approximately described as a linear combination of only a few same eigenvectors (i.e. contribution eigenvectors) for both the ideal structure and a random real structure. Therefore, the problem of expanding static displacements is transformed to obtain the combinational coefficients of the contribution eigenvectors. An iterative strategy based on the Fisher information matrix comprised of contribution eigenvectors is then suggested to optimize the tested locations and to obtain the unbiased combinational coefficients. A Geiger cable dome is numerically analysed. The results show that the unified expression of the static displacements under a specific load is correct, and good expansion results are obtained by the proposed method.