Multiple internal resonances and modal interaction processes of a cable-stayed bridge physical model subjected to an invariant single-excitation

• Published in: Engineering structures 2018-10, Vol.172, p.938-955
• Main Authors: Sun, Ceshi, Zhao, Yaobing, Peng, Jian, Kang, Houjun, Zhao, Yueyu
• Format: Article
• Language: English
• Subjects: Beat frequencies; Beat vibration; Cable-stayed bridge; Cable-stayed bridges; Cables; Concrete construction; Engineering; Excitation; Experiment; Filtration; Finite element analysis; Finite element method; Forced vibration; Highway construction; Hybrid modes; Interaction process; Invariants; Mathematical models; Modal analysis; Multiple internal resonance; Resonance; Signal processing; Transient analysis; Vibration; Vibrations
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2018.06.088

•A fine physical model of cable-stayed bridge with 44 cables was manufactured.•Multiple internal resonances were observed under an invariant single-excitation.•Large vibrations of deck/pylons and “beat vibration” of long cables were observed.•Vibration curves of the deck/pylons were one to one linked to the MECS FE modes.•The mechanisms and processes of the multiple internal resonances were revealed. There exist complex internal resonances in cable-stayed bridges. In order to study multiple internal resonances under the excitation of an invariant single-excitation and to ascertain the modal interaction processes, a nonlinear dynamic experiment of cable-stayed bridge was carried out. The modal parameters of the experimental physical model were evaluated by two finite element models (the OECS and MECS). Mode shapes were classified and compared to distinguish the in-plane and out-of-plane as well as the global, local and hybrid modes. Potential internal resonances were recognized by investigate the ratios between cable frequencies and the OECS frequencies. Then, attention was paid not only to the steady-state responses but also the coupling processes. It was observed that multiple internal resonances could induce large amplitude vibrations of the entire bridge, including the “beat vibration” of long-cables. Moreover, the sum of the two beat frequencies was equal to the excitation frequency. These phenomena were also found in transient analysis by the MECS finite element model. The interaction processes of the multi-mode resonances were revealed by separating vibration signals using the zero-phase-shift filtering technology and by precisely linking the observed modes to the MECS modes with frequency relations. Research shows that: the forced vibration, 2:1 local-local internal resonance and combined internal resonance had occurred simultaneously in the physical model.