Research On Vibration Control Of Large-span Ground-anchored Suspension Bridge By Using A New Type Of Pseudo-linear Friction-variable Hysteretic Curve Damper

With the progress of society and the development of technology, large-span suspension bridges develop rapidly. Large-span bridges are transportation junctions, have huge impact on the national economy, it results in huge losses once they are damaged by earthquakes, thus, it is necessary to consider and implement seismic measures and fortification against earthquakes while designing and analyzing suspension bridges, vibration control is one of the most effective way among them. In order to ensure the life, safety of the bridges, to protect national property and lives of the people, it is necessary and significant to do research on the subject of vibration response control of large-span suspension bridges.There are many ways to implement vibration control of bridges. We use a new type of pseudo-linear hysteretic curve damper with friction-variable characteristics which developed by our research group to control seismic response of large-span ground-anchored suspension bridges. The new type of pseudo-linear hysteretic curve damper with friction-variable characteristics is a kind of displacement-related friction-variable damper, it structures simple, price-to-performance ratio is good, it can be used in all types of structure. This new kind of damping device has a uniform friction coefficient, the friction force between the inner friction ring and the inner wall of the sleeve cylinder while the ring moves is proportional to the displacement amplitude by changing the inside diameter of the sleeve cylinder, the direction of friction is the same as the velocity's, thus it can express a approximate linear hysteretic damping characteristics, the ability of energy dissipation provided by the hysteretic curve is strong. The main contents of this dissertation are described as follows:1. Based on the previous research achievements in this field, structural features and earthquake damage features of suspension bridges are discussed and summarized, several commonly used ways of bridge structures control are enumerated.2. A new type of pseudo-linear hysteretic curve damper with friction-variable characteristics are presented and introduced, the hysteretic characteristics and mechanical properties of the damper are shown, the loading and unloading experiment results of the damper are given. Based on ANSYS material subroutine (USERMAT) and secondary-development function of ANSYS, the new type of pseudo-linear hysteretic curve damper with friction-variable characteristics hysteretic model subroutine is developed which can adjust its hysteretic and negative stiffness characteristics. Hysteretic curve with negative-stiffness characteristics is realized for the first time, the new characteristics of the damper can be used in numerical simulation by calling the user-defined subroutine in custom-created ANSYS. User can directly install the new type of pseudo-linear hysteretic curve damper with friction-variable characteristics into bridge structures by using the subroutine which can popularize its application into engineering structures.3. On the basis of a large-span ground-anchored suspension bridge, modal of this ground-anchored suspension bridge has been analyzing, structure free vibration characteristics and earthquake response has been studied.4. On the apply of the new type of pseudo-linear hysteretic curve dampers with friction-variable characteristics in longitudinal direction of the large-span ground-anchored suspension bridge, comparing with the viscous dampers, the characteristics and regularity of damping of the new friction-variable dampers has been summarized by dynamic analyzing while the damping effects of the dampers has been analyzed.