Double Earthquake Damping Control Research Of Vibration Isolation Of Building Roof Steel Tower Bottom And Building Roof Steel Tower As TMD

In recently years, some steel structure towers which are built on the roof of the high buildings have been appearing almost everywhere. However, the earthquake damage data shows that the earthquake acceleration of the protruding steel tower on the top of the high building is always strengthened greatly through main structure when the strong earthquake occurs. The horizontal seismic effect to the steel tower is more than that if it's just on the floor, which will make the steel tower have obvious whiplash effect. So how to avoid the whiplash effect of the steel tower atop building has been greatly concerned. This paper will mainly have research on vibration isolation of the steel tower when seismic isolation measure are used at the bottom of the steel tower atop building and steel tower having damping effect to the main structure.The paper first introduces the basic principle of the isolated structure and the TMD system and establishes the TMD mode of two degree of the freedom steel tower atop building and dynamic equations. Compile two degree of freedom time history analysis program through using MATLAB language; analyze the calculated results under the seismic waves through changing the horizontal stiffness of the isolated layer and the parameters, such as damping ratio; conclude the earthquake respond principle of the TMD structure of the steel tower atop building. And also give the suggestion on construction of the building for the shock isolation unit of the TMD of the steel tower atop building.Then, one four-floor steel frame model is built by huge general use finite element software SAP 2000. Under the different earthquake waves have time history analysis and comparison the three models: the model without steel tower atop building, the model only with the steel tower atop building and with a TMD system of the steel tower atop building. The analysis results show: under the condition when without steel tower atop building the main structure have the most obvious response; under the condition when steel tower atop building the response is relatively weak and the steel tower atop building has the most great reaction under the whiplash effect; while with the TMD of the steel tower atop building the reaction of the main structure and steel tower decline to their lowest point.The research suggests that the TMD of the steel tower on the top of the building can reduce the earthquake response of main structure and steel tower effectively and simultaneously to avoid the whiplash effect and get a better damping shake effect.