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Elastic cables have the advantages of desirable seismic mitigation effect, low cost, and convenient installation, and have been used widely in low-to-mid-span bridges. However, their utilization in long-span cable-stayed bridges has been limited. To study the effect of elastic cable on the seismic response mitigation of long-span cable-stayed bridges, an experimental model (half-bridge model) with a geometric similarity ratio of 1∶40 was established. Both the semifloating system and the elastic restraint system were considered, and the seismic responses of the two systems under earthquake excitation were tested on the shaking table. The results demonstrated the seismic mitigation effect of the elastic restraint system, which is dependent on the characteristics of the seismic wave. The mechanism of the seismic response mitigation of the long-span cable-stayed bridge with longitudinal elastic restraint was discussed. [ABSTRACT FROM AUTHOR]

Cross-sea–cable-stayed bridges located in earthquake-prone areas can be subjected to earthquakes, wave action, and other dynamic loads of potential threats during their construction and service periods. The dynamic response of a cable-stayed bridge was studied under the combined effects of earthquakes and wave flow. In this study, a cross-sea–cable-stayed bridge is investigated as a prototype. ANSYS software was used to establish a spatial finite-element model, and CFD software was used to simulate the wave loads and calculate the fluid-structure coupling. The peak displacement at each location was determined under different loading conditions during the combined action of earthquakes and waves. The displacement at the top of the tower was the largest, followed by that at the main span. However, when the wave action was severe, the peak displacements of the tower top and main span were comparable, and these two peak displacements occurred simultaneously. The internal-force-response law at the bottom of the tower tended to be consistent, and only the peak values differed. The peak change in the shear force was smaller than that in the bending moment. Earthquakes and waves had a negative effect on bridges; however, they played a dominant role. Nevertheless, the presence of waves alters the dynamic response during joint action; therefore, the effect of waves on the bridge cannot be ignored. The root-mean-square (RMS) under the joint action of earthquakes and waves was evaluated using the RMS of superimposed independent earthquakes and independent waves. However, it can be observed that the joint effect is not a simple superposition effect. Complex interactions exist between the earthquakes and waves. • Using a cross-sea cable-stayed bridge as a background, a spatial finite element model of the bridge was established by ANSYS, and wave loads were simulated by CFD software. • Investigating the dynamic response of bridge key sections under the combined action of earthquakes and waves. • Proving that the combined effects of earthquakes and waves on bridges are not a superposition of dynamic responses, but a complex coupling between earthquakes and waves. [ABSTRACT FROM AUTHOR]

To research structural performance of extra-large-span cable-stayed bridge under different section forms, with the engineering background of a 800m main-span cable-stayed bridge with steel truss girder, the cable-stayed bridge with steel box girder is designed according to the current bridge regulations when two bridges are designed in an ultimate state of the carrying capacity, so the maximum stress and minimum stress of the stress envelope diagram are substantially the same. A comprehensive comparison is given to two types of bridge on the aspect of static force, natural vibration frequency, stability, economic performance and so on. Analysis results provide future reference for the large-span cable-stayed bridge to select between the steel truss girder and the steel box girder.

The global stability of a structure, the stiffness of its main girder and concrete tower, and the variation of the forces of its stay cables are key issues to the safety assessment of an in-service cable-stayed bridge. The efficiency and rationality of local elaborate non-damage-identification could be enhanced by the primary damage identification of cable-stayed bridges on the basis of periodic detection of the cable force and strain monitor in key sections of the main girder. The genetic algorithms of damage identification for cable-stayed bridges were investigated in this paper on the basis of the monitor data of the cable force and strain in a key section of the main girder. A damage detection program for complex civil structure was generated to implement the identification of damage location and extent. The deterioration of the structure was calculated according to the variation of monitor data. It is demonstrated that the results of damage identification from the parametric finite element method are accurate. The method had been verified using a long-span concrete cable-stayed bridge in Ningbo, which has been in use for the past four years. [ABSTRACT FROM AUTHOR]