Dynamic characteristics of a cable-stayed bridge measured from traffic-induced vibrations

Abstract

This paper studies the dynamic characteristics of the Kao-Ping-Hsi cable-stayed bridge under daily traffic conditions. Experimental data were measured from a structural monitoring system, and system-identification techniques, such as the random decrement (RD) technique and Ibrahim time-domain (ITD) method, were adopted. The first five modes of the bridge were identified for their natural frequencies and damping ratios under different traffic loading conditions, in terms of root-mean-square (RMS) deck velocities. The magnitude of the torsion mode of the Kao-Ping-Hsi cable-stayed bridge is found to be one order-of-magnitude less than the transfer mode, and two orders-of-magnitude less than the vertical modes. Out results indicated that vibrations induced by traffic flow can be used as an indicator to monitor the health of the bridge due to their insensitivity to the natural frequencies of the cable-stayed bridge. Furthermore, the damping ratios may be used as a more sensitive indicator to describe the condition of the bridge.

Improved Rigid Cable Method for Pre-Stress Optimization in Suspend-Dome Structures

“…The second is rigid cable method, which references the analysis method in the cable-stayed bridge pre-stress. It is achieved by do static analysis without pre-stress after multiply elastic modulus of lower cables, and then define proportion among each pre-stress based on the results [2,3]. The third is the tangential balance method, which determines the proportion of each circle's pre-stressing based on principles that make sure external impulse proceeds from inner circumferential radial cables and outer neighboring ones connected at upper chord node pre-stressing is conformed to the upper layer reticulated shell' spherical tangential [4,5] .The analysis and contrast research on the examples proved that the stress and nodal displacement of upper chords member are even when rigid cable method is used, while pre-stress given by geometric method and tangential balance method will bring the shell wavy [4,5].…”

Operational Modal Analysis on Bridges: A Comprehensive Review

“…Cable-stayed bridge identification was further explored by Wu et al [119], who introduced a mode separation technique utilizing ITD for parameter identification. The application of ITD can also be followed in these papers [120][121][122].…”