Analytically measure the vibratory characteristics of the cable-stayed bridge during dual-cantilever erection

To analytically measure the vibratory characteristics of the cable-stayed bridge with beam-tower constraint during the dual-cantilever erection, the isolating/assembling technique is used to derive the global equation. Eigen-equation governing the frequencies/modes is obtained by applying the coefficients vectors transferring between adjacent cable-beams and the boundary/matching conditions. An illustrative example of the dual-cantilever erection system is given to verify the effectiveness of the analytical method by comparing with the finite element method. The influences of the vertical/rotational beam-tower constraint stiffness and the beam/cable relative stiffness on the frequencies/modes are studied; the sensitive interval and unstable/veering regions in frequency spectrum are ascertained. The twin frequencies are analytically measured and it is found that the symmetry plays a fundamental role in its existence and distribution range. The measuring method supplies reference for similar cable-supported structures; the results provide suggestions to avoid unstable/veering zone depending on the designed parameters combination in cable-stayed bridge.