The authors have addressed the change of main cable tensioning force as the means of suspension bridge stiffness control. An ANSYS 3D model of a suspension bridge was developed. The dead load stress-strain behaviour and dynamic response of the model were analyzed. The study has shown that 7.5 fold increase of the main cable pre-tensioning force reduced the displacement in the middle of the central span of the stiffening girder by 40%, while in the middle of the end span, a 9% increase in displacement was observed; and displacement of the tower apex reduced by 28%. Modal analysis has shown that the main cable pre-tensioning force in the 3D model had effect neither on the natural vibration frequency spectrum of the structure, nor on the distribution of the principal modes in the spectrum. With a 7.5 fold increase of the main cable pre-tensioning force, the values of natural fundamental frequencies have changed within 2% range. The results obtained by the authors allow for the conclusion that varying the pre-tensioning force of the main cable has little effect on a suspension bridge dynamic response control. At the same time, pre-tensioning of the main cable allows control over the stiffness of the hybrid cross-tie system.
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