Research On NiTi SMA Damper Used In Cables Of Cable-Stayed Bridges And Other Kinds Of Cables

Structural vibration energy dissipation is a kind of structural control technology, which employs energy-dissipation devices installed in proper locations of the structure to dissipate part of structural vibration energy under earthquake and wind so as to reduce the structural vibration response. Shape memory alloy (SMA) is an ideal material to dissipate vibration energy because of its properties of shape memory effect (SME), super elasticity effect and damping effect. So the shape memory alloy damper, which is based on these properties, is a good kind of energy-dissipation device. It can reduce the seismic and wind-vibration response of the engineering structures effectively. So the studies on the shape memory alloy damper are valuable in theory and practice.The current situations of researches and applications of shape memory alloy damper are briefly reviewed in this thesis firstly. A new type of damper device based on shape memory alloy (SMA) wires is developed for structural control implementation. Then the theoretic and experimental study of this new type of damper technology for structural vibration energy-dissipation is performed to verify the vibration energy dissipation ability of the new type of SMA damper. Finite element method is adopted to analyze the vibration of cables installed by SMA damper. An experimental model of cable-stayed bridges is designed to do cable structure control experiments in all kinds of situation. Finally, The main contents and results are as follows.1. Based on the properties of the SMA, a new type of damper device based on shape memory alloy (SMA) wires is developed for structural control implementation. This kind of damper can control the vibration of structures of cables and poles in all directions which is vertical about the axis of cables or poles. It can transform of all directions into tension force and compression force. So it can especially be used in cable and pole structures.2. The theoretic study on such damper is performed, including the research on fundamental damping principle of the damper and mechanics damping analysis of such developed reduced-scale damper. The various affecting factors to the working performance of SMA damper are discussed. The formula of the output damping force and displacement is gotten when the damper is tensed or compressed.3. The dynamical experiment of such reduced-scale damper is performed to verify the damping analysis results and the vibration energy dissipation ability of the new type of SMA damper. It is found that the experimental results are in good agreement with the theoretic values.4. From the experimental restoring force curve, the damping coefficient and stiffness of damper are calculated. Based on these parameters of the damper, finite element method is adopted to analyze the vibration of cables controlled and uncontrolled by SMA dampers. The numerical results illustrate that displacement of the frame model is reduced greatly and its vibration decay rate is increased effectively after the developed SMA dampers are fixed in it.5. An experimental model of cable-stayed bridges is designed to do cable structure control experiments in all kinds of situation. It is found that the experimental results are in good agreement with the theoretic values.