An approach for choosing optimal actively-stretched cablesof cable-strut tensile structures based oneigenvalue of sensitivity matrix

An appropriate choice of actively-stretched cables is the main measure to control the pretension deviation during the construction of cable-strut tensile structure. The quadratic sum of elemental pretension deviations is adopted as an index to evaluate the pretension deviation of the whole structure. By means of the spectral decomposition of the sensitivity matrix, which reflects the relationship between cable length errors and pretension deviations, this index can be expressed as an analytical form relating to the cable length errors, the eigenvalues of the sensitivity matrix as well as its eigenvectors. Theoretically, the different choice of actively-stretched cables is expounded to lead to change of the eigenvalues of sensitivity matrix, and directly impact on the control effect of structural pretension deviation. Due to the rapid attenuation of the eigenvalues of sensitivity matrix, the unfavorable structural pretension deviation can be effectively estimated by only using its first-order eigenvalue and eigenvector. Adopting the first-order eigenvalue of sensitivity matrix as the evaluating indicator, an optimization algorithm for choosing actively-stretched cables is put forward based on the Genetic Algorithm. The optimal actively-stretched cables of a practical cable-strut tensile structure are analyzed under different conditions. The results reveal the validity of the method put forward in this paper.