Experimental Investigation on Damage Identification of Cable-Stayed Arch-Truss Structures Using Modal Parameters

In this paper, the experimental research on the damage identification method based on modal parameters for the cable-stayed arch-truss was conducted. Two test models of 6 m-span cable-stayed arch-truss were designed and fabricated. The structural damage was simulated by replacing the normal members with struts of different cross sections. Different damage conditions such as damage of the arch-truss members and the damage of the cable-strut system were designed. The modal parameters of first three orders were obtained through dynamic test for each damage condition, and the test results were analyzed by the combined identification method which was based on the vibration modal parameters: the top arch-truss was diagnosed by curvature modal difference method and modal flexibility difference curvature method. The regularized frequency change rate method is used to diagnose the bottom cable-strut system. The damage identification test results show that the curvature modal difference method and the modal flexibility difference curvature method have better effect on the damage identification of single-damage and multiple-damage of the cable-stayed arch-truss. And the recognition effect of the upper chord is better than that of the lower chord. Compared with the curvature modal difference method, the mutation of non-damage position is smaller and interference items are less by using the modal flexibility difference curvature method, leading to a better recognition effect; the regularized frequency change rate index of the first three orders’ frequency can effectively identify whether the cable support system is damaged. However, damage positioning for symmetrical position needs further verification.