Theoretical Research And Shaking-Table Test On Vibration Control For Long-Span Bridges Using Shape Memory Alloys

With social and economic development, the spans of modern bridges tend to long, and the seismic safety of long-span bridges as the lifeline engineering, presents more important. Structural vibration control is an effective method for seismic design of long-span bridges, and at the present time, it is active demand to find an economic, practical, effective and no-energy required control measure, and to establish the corresponding theory and method. As a kind of new smart material, Shape Memory Alloys (SMA) have specific properties of shape memory, super elasticity and high damping, and have been paid more attention in the field of structural vibration control.In this dissertation, a new damper and a smart isolator are developed using the smart SMA material, and the vibration control on seismic responses of long-span bridges is performed to build a kind of vibration control system of long-span bridges and to improve the seismic performance of the long-span bridges, which presents important significance in theory and substantial value in engineering. The key developments and creative achievements are contained in this dissertation as follows:(1) Establishment of constitutive model of SMA and Test on properties of SMA. Based on the summary of existed constitutive models of SMA, a constitutive model of SMA is established through the training and the test on properties of SMA. For the use in vibration control of cable-stayed bridges, a SMA damper with outstanding properties is proposed and its model of restoring force is built through model tests.(2) Analysis and control for parametric vibration of cable-stayed bridges. The FE analysis model for vibration of staying cables is established, the vibration types of staying cables and the corresponding control measures are explored, and the parametric vibration of cable-stayed bridges is emphatically investigated. The control on the parametric vibration of long-span cable-stayed bridges is carried out using SMA, and the numerical simulation presents perfect control effect.(3) Development of SMA-composite rubber bearing and investigation on isolation of bridges. Employing the shape memory effect and outstanding damping property of SMA, a new adaptive isolating bearing, i.e. SMA-composite rubber bearing, is developed. The system and analysis model of adaptive isolated bridges is built based on the SMA-composite rubber bearings, and the time-history analysis for the seismic responses of isolated bridges is completed using the SMA-composite rubber bearings to prove the effectivity, practicability and adaptability of the SMA-composite rubber bearing.(4) Theoretical research and shaking-table test on vibration control for seismic responses of long-span cable-stayed bridges using the SMA damper. The theory and numerical method for vibration control of long-span cable-stayed bridges is proposed using the proposed SMA damper, and the significant damping behavior of the SMA damper and its control effects on the seismic responses of long-span cable-stayed bridges are verified through the shaking-table test. The tested results are much identical with the numerically simulated results, and this proves the accuracy of the model of restoring force of the SMA damper.