Compositive Optimal Control of the Seismic Response for Super-Long-Span Suspension Bridges

In order to reduce the seismic force of the towers,the seismic isolation system is commonly adopted in super-long-span suspension bridges.But in this system,the seismic displacement at the end of the main girder may exceed the allowance,so suitable devices should be employed between the towers and the main girder to control the displacement.Based on the mechanism of vibration control,this paper investigated the selection of practical connection devices and the determination of their parameters,and the concept of compositive optimal control was proposed combined with modified AHP method.The Runyang Suspension Bridge with a main span of 1 490 m was taken as an example.After 3-dimensional nonlinear seismic analyses using different parameters of connection devices were carried out,the compositive optimal parameters of the connection devices were achieved.Results showed that both the elastic connection devices and the dampers with rational parameters could significantly reduce the seismic displacement of the bridge,but the dampers were better if all factors were considered.