Response Of Long-span Cable-stayed Bridge Research Articles

Quantifying site-response effect of spatial variability earthquake on seismic failure mode of long-span sea-crossing cable-stayed bridges

Long-span cable-stayed bridge is a prevalent bridge type for sea-crossing passages and occupies an essential role in the transportation system. Non-uniform excitations significantly impact the response of long-span cable-stayed bridges, especially the site-response effect (ESR), which is one of the three primary characteristics. This paper employs a long-span sea-crossing cable-stayed bridge with consideration of hydrodynamic and pile-soil effects to systematically study the influence regularity and parameter sensitivity of the site parameter ωc on the response of critical components, and develop probabilistic seismic demand models between each component and ωc. The results reveal that the fragility of each component exhibits dissimilar sensitivities related to ωc, specifically, the changing amplitude of bearing fragility is greater than that of the bridge pylon. Consequently, when the soil type at the pylons changes from soft to solid, the damage sequence of the main pylon, pier and bearing has been changed, which exhibits different damage mechanism and failure mode. Furthermore, the mathematical model between the seismic parameters and damage mechanism is established to quantify the impact of ESR on the failure mode of sea-crossing cable-stayed bridges. Thus, it could provide a theoretical basis for the earthquake damage assessment and seismic optimization of long-span cable-stayed bridges.

SEISMIC RESPONSE ANALYSIS OF LONG-SPAN CABLE-STAYED BRIDGE WITH NONLINEAR VISCOUS DAMPERS UNDER DIFFERENT PERIODIC SEISMIC WAVES

In order to study the effect of nonlinear viscous dampers on the seismic response of long-span cable-stayed bridge under different periodic seismic waves, as Erdong Yangtze River Bridge which main span is 926 meters in Hubei province of China for the research object, nonlinear viscous dampers are simulated by Maxwell model, and four viscous dampers are set at the joint of main tower and beam. The displacement and internal force responses of cable-stayed bridge with different velocity index and damping coefficient of nonlinear viscous dampers are analysed and discussed, in the situation of that long period and ordinary period seismic waves are input as earthquake motions. Analysis results show that: the displacement and internal force responses of long-span cable-stayed bridge under long period seismic wave are more negative; the displacements of key nodes of bridge can be reduced effectively by nonlinear viscous dampers; the internal force responses of bridge would be influenced greatly by the combination of different parameters of viscous dampers; the growth of shear and bending moment at the bottom of the tower can be controlled in an acceptable range by the reasonable parameter combination; the ideal parameter combination is that velocity index of viscous damper is 0.6 and the damping coefficient is 7000 N.(s/m)α for this cable-stayed bridge under long-period seismic wave.

Static Parameter Sensitivity Analysis of Long-Span Cable-Stayed Bridge Based on RSM

AbstractThe response surface method (RSM) was used to construct the explicit response equation between design parameters and structure response. This method was also used to analyze the sensitivity of the parameters. Accordingly, the influence degree of various design parameters on the response of long-span cable-stayed bridge was analyzed. The sensitivity factors of the design parameters solved through the explicit response equation could show the tendency of internal force, deformation, and cable force of a long-span cable-stayed bridge under the condition of changing design parameters. These design parameters were divided into four importance ratings according to the sensitivity percentage value. This task could quantitatively distinguish the influence degree of the design parameters on the structural response. The method could provide the reference for parameter sensitivity analysis and identification of a long-span cable-stayed bridge.

Effect of Pounding at Expansion Joints on Seismic Response of Long-Span Suspension Bridge under Strong Earthquakes

For a long-span suspension bridge, owing to a flexible structure system, the seismic displacement at the end of the deck may severely exceed the allowance under earthquake which due to the occurrence of the pound between the main span and the approach span usually which can causes the collision of falling-beams and structures. In this paper, based on the pounding phenomenon at expansion joints of long-span suspension bridge under strong earthquake and employing a typical long-span suspension bridges. With the time history analysis method of determining the nonlinear seismic responses, the pounding effects of adjacent girders at expansion joints on seismic responses of long-span cable-stayed bridge were studied. The results indicate that pounding can amplify the seismic demand of piers of the approach span and can also amplify the displacement of beam of the approach span, the relative displacement between main span and approach span and the hinge seat width of beam of approach span obviously and it causes easily the collision of falling-beams and structures under earthquakes.

Background component of buffeting response of cable-stayed bridges

For practical purpose, buffeting response of cable-stayed bridges to wind excitation is usually analytically determined by single-mode-based method, and the resultant response is written as the composition of the resonant component and the background component by the square root of sum squares (SRSS) method. The background component is sometimes neglected for simplifying computations. In the present paper, numerical computations on four representative cable-stayed bridges in China indicate that the background component usually has a significant contribution to the buffeting response of long-span cable-stayed bridges. Parametric studies on the effects of structural parameters on the buffeting background components for these four bridges are also performed. A simplified method introduced in literatures for estimation of the background component of buffeting response is then briefly discussed. Finally an approximate method for estimating the first vertical bending mode-buffeting response of cable-stayed bridges is proposed.

Parametric study of cable-stayed bridge response due to traffic-induced vibration

The dynamic response of long-span cable-stayed bridges due to moving traffic loads is investigated utilizing three-dimensional models. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept, presented by discretization of cable into several elements, is used to study the effect of cable vibration on bridge dynamics. A computer algorithm is developed to simulate the applied traffic loads for both directions of the bridge deck. The algorithm is flexible in terms of handling different loading capacities, speeds and configurations. Parametric studies are conducted to investigate the effect of cable vibration, damping, vehicle-structure interaction, random roughness of the bridge deck, as well as span length and vehicle-speed. Cases of asymmetric traffic loading clustered in one direction are also considered in order to study the torsional response of the bridge. Results are discussed, summarized and plotted.