Dynamic response analyses of long-span cable-stayed bridges subjected to pulse-type ground motions

This paper presents the dynamic response analyses of a special long-span cable-stayed bridge with the main span length of 680 (m) subjected to pulse-type ground motions. The 1/100 scaled shaking table test are developed herein to verify the accuracy and correctness of the 3D finite element (FE) model of the examined long-span cable-stayed bridge on the software platform of SAP2000. To systematically investigate the influence on the seismic responses and on the selection of the nonlinear viscous damper parameters of the employed long-span cable-stayed bridge both the near-fault pulse-type ground motions and the far-field ground motions are selected as the seismic inputs of FE model. Some important conclusions are drawn that the near-fault ground motions usually causes the larger peak responses (e.g., Tower top displacement, girder end displacement, and moment of tower bottom) of the long-span cable-stayed bridge compared with the far-field motions, namely the near-fault ground motions are more destructive to the structures. The displacement responses can be amplified approximately 2-3 times and the damper parameters (Damping coefficient C and damping index alpha) of nonlinear viscous dampers can be affected by the ground motion characteristics. The damper parameter values are changed from the C = 3000 and alpha = 0.3 in far-field earthquakes to the C = 6000 and alpha = 0.2 in near-fault earthquakes, namely the near-fault ground motions obviously increase the demand of energy consumption of general nonlinear viscous dampers.