Behaviour Analysis Of Self-anchored Suspension Bridge And Vibration Response Control Of The Tower

Self-anchored suspension bridge is a new type of bridge, static and dynamic characteristics research of which is still quite lacking, particularly test research. Bridge tower height and the vibration characteristics are changing with the construction process. Thence, in the various stages and different seismic intensity, the optimal parameters of its anti-seismic devices are changing. The parameters of conventional tuned mass dampers (TMD) or tuned liquid column damper (TLCD) are fixed, so they can not achieve the optimal anti-vibration effect in different construction stages and different seismic intensity. Few study are carries out on the seismic vibration control of bridge tower with MR-TLCD, which is a combination of the magneto-rheological damper and tuned liquid column damper.Taking Beiguan self-anchored suspension bridge in Jiangshan, Zhejiang Province, as the background in this paper, the reasonable bridge status of Beiguan Bridge is determined first. Combined with the static and dynamic characteristics experimental study, it's proved that under the action of live loads, the self-anchored suspension bridge are linear elastic and the stiffness of the bridge meets the specifications. The first-order testing frequency of the main beam, the main cable, the main tower are consistent with the theoretical value.In case of sudden earthquake, high-rise bridge towers in the periods of construction will be destroyed easily, so it is necessary to take some control methods for the bridge towers to be protected from vibration effects in the the construction process. The vibration frequency and damping characteristics of bridge tower are changing in the construction process, while the dynamic parameters of passive TLCD can not change. Based on the general TLCD, this paper uses friction-type magneto-rheological damper to make improvement on the valve between the parts, which has simple structure, adjustable damping force, and quick response; meanwhile, change the natural frequency of TLCD by adjusting the pressure of enclosed air in the vertical columns. Improved MR-TLCD doesn't only have the function of real-time adjustment(MR damper), but also the advantages of simple structure and low cost (TLCD). Relative to the viscous-type MR-TLCD, mechanical model of friction-type is more simple, which avoids uncertain relationship between the voltage and the damping force. Then, using Matlab's Simulink program tool, the high-rise structure model (single degree of freedom, multi degree of freedom structure) vibration control with magneto-rheological-type liquid column damper (MR-TLCD) is analysed. After that, seismic response control of towers during construction stages is carried out. The results show that as the voltage (friction), pressure (frequency) changes, there is a best combination between the two values. The control effect of acceleration is better than displacement. The variation of displacement and acceleration reducing effect with the changing of frequency ratio, frictional force (voltage) under the conditions of different mass ratio is studied. The results showed that the ideal frequency ratio is around l, and friction value has a optimal value. Considering about the economic and practical factors, mass ratio is appropriate to be 1%.