The Internal Force Analysis Of Base-isolation Structure Under Vertical Load And The Research On The Transient Vibration

The base-isolation is a new type of passive control technique. The isolation system is placed between superstructure and its foundation. The purpose of it is to reduce the lateral stiffness and prolong the natural period of structure. As a result, the structure can keep away from the period of ground so that the seismic response can be reduced greatly. In this paper, the concept of the vibration control for civil engineering was introduced. Meanwhile, the mechanism and the research of the base-isolation were also reviewed briefly .Two key issues of the base-isolation structure were researched. One was about the internal force of base isolation structure under the vertical load; the other was about the transient vibration of base isolation structure. The main research work and conclusions are as follows:1, The internal force of base isolation structure under vertical load was analyzed in order to observe the characteristic of it while the influence factors changed. The distribution regularity of the internal force was compared with the non-isolation structure. The results showed that the moment of the first floor columns was increased obviously.2 , The characteristic of the internal force was generalized and the concept of the isolation influencing factor was propounded. The simplified formula of the isolation influencing factor was deduced. The results of simplified formula comparing with the exact result showed that the formula was adaptable in certain condition.3 , Some problems about the transient vibration of SDOF under simple harmonic load and ground motion was researched. The rule of the transient vibration was generalized.4, The method of the wavelet transform was introduced into analyzing the transient vibration of base-isolation structure. The displacement response, the acceleration response and the internal force response of the SDOF were analyzed by using the wavelet transform. As a result, the transient vibration was separated from the overall response. It showed that the transient vibration was the main constituent in the seismic response of the base isolation structure.