Researching On The Effects Of Seismic Response About The Isolation Bearing Position On The First Floor Isolation Building

The first floor seismic isolation is set in the first floor of the building structure, it's belong to the special case of the inter-layer seismic isolation technology, and the analysis shows that the first floor seismic isolation can reduce the horizontal seismic acceleration of the structure by about 65%. At present, the research on the longitudinal position change of the seismic isolation bearing is relatively weak in China, and the dynamic elastic-plastic response of the structure under the rare earthquake has been a hot spot in the research of earthquake resistance.By the finite element software ETABS in this paper, there is the six-floor frame structure as an example by taking a practical project as the background, and in consideration of the change of the position of the bearing in the column, meanwhile the bearing property, the column parameter and the initial stiffness of the first story isolation structure are adjusted,then it do the following works through the calculation analysis:(1) The seismic isolation bearings are respectively arranged on the top and the foot of each column in the two different positions, and the seismic response of the first floor isolated buildings under moderate and strong earthquakes are analyzed, at the same time, it's studied on the influence of the support position on seismic response(including displacement,acceleration, shear force, deformation of isolation bearing and so on) and found the relevant regularities.(2) While a study on the bearings in different positions, the isolation layer respectively with different parameters, and it explores the design method of the isolation layer structure by the six-floor frame structure model.(3) It's studied on the influence of the position change of the isolated bearing on the elastic-plastic state of the isolation layer structure, and the failure modes of the isolated layer are compared with the two cases.From the above researches, this paper obtains the following conclusions:(1)This paper established the elastoplastic analysis model of the simplified layer isolation structure, and the vibration isolation effect has changed while the changes of the bearing property, the column parameters and the stiffness of the first floor(2)When the first floor seismic isolation structure is isolated that the isolated position changes from the roof-isolation to the column base isolation, the damping effect of the column base isolation is improved, and the displacement of the seismic isolation layer compares to the roof-isolation is reduced by 12%, and the corresponding displacement angle is reduced by 9%, moreover the stress of the isolation bearing is reduced by 11%, and the seismic effect of the whole structure is improved by 8%.(3)The position of the isolated bearing is different, and the failure mode of the whole structure is also affected. The results show that the emergence of plastic hinge and the time of emergence are changed when the isolated position changes from the roof-isolation to the column base isolation.The research in this paper may be applied to the design of the first floor seismic isolation system which has the theoretical significance.