Study On Seismic Design And Effect Analysis Of Cable-stayed Bridge By Multi-TMDs

As a large and complex spatial structure, a large-span cable-stayed bridge has large flexibility and low damping characteristics, and is easy to vibrate under dynamic loads. Especially under seismic loads, it will be very easy to cause significant vibrations of superstructure and produce large internal forces in key positions, which may be lead to structural damage and failure. So it is vital to consider seismic mitigating design of the cable-stayed bridge. In this paper, based on summary of the former researches of structural vibration control and the seismic mitigating design of cable-stayed bridges, multi-distributed TMDs(multi-TMDs) as a control counter measure are used to make seismic mitigating design of the cable-stayed bridge, the main contents are as follows:1. Otimization of TMD parameters are studied. Classic optimization method taking dynamic magnification factor as objective function and H2/H∞optimization methods taking H2/H∞norms of system transfer function as objective function based on morden control theory are discussed respectively, simulations using these three optimization methods are achieved by Matlab programs.2. Taken a simple 3-story frame structure as an example, optimization design of multi-TMDs and seismic controls are carried out. Focusing on two states of the structure, i.e. non-close eigenfrequency and close eigenfrequency, control efficiencies for the structural seismic response by these three methods are analyzed and discussed, results show that multi-TMDs optimized based on H2/H∞mehods have more advantages than classic method for vibration control of close eigenfrequency structure.3. Focusing on a cable-stayed bridge under construction and its completed state respectively, the control design models are established, and analysis on dynamic characteristics and seismic responses of the cable-stayed bridge are achieved. Furthermore, optimization design of multi-TMDs aiming at the main contribution modal shapes for structural response are carried out. The seismic responses of the cable-stayed bridge under construction and its completed state subjected to different excitations are simulated and evaluated. Results show that good control effects are achieved by the multi-TMDs for the seismic response mitigation of the cable-stayed bridges.