Study On The Application Of The Minimum Seismic Base Shear Force Considering The Site Effect

With the development of economy and architectural technology, more and more structures of long-period such as super high-rise buildings and large span structures have been built. An unreasonable phenomenon has been met by structural designers when they design the structure of long-period that the super high-rise buildings which under good site classification are less likely to meet the demand of shear-gravity ratio than those under worse site classification. This is because the influence of site classification to the peak value of response spectrum hasn’t been considered in response spectrum theory. The shear-gravity ratio selecting is only related to fortification intensity, while the site classification makes no sense. Thus the selecting of shear-gravity ratio is unrelated with the site classification. This paper, based on the influence of site classification to peak values of response spectrum and researching on shear-gravity ratio of long period structures that are from both here and aboard, analyzed the relationship between the shear-gravity ratio and site classification from the aspect of structure seismic and put forward the ratio adjustment coefficient, and compared with the specification ASCE 7-10. The main researches of this article are as follows:First of all, it introduces the research status of the influence of site classification to response spectrum’s peak value and the shear-gravity ratio of long period structure. Then eighty-four frame-core wall structures have been built according to different fortification intensity and site classification. The differences of seismic response of structures with three different kinds of adjusted methods that aren’t available, adjusting intensity, site parameter and stiffness to adjust the shear-gravity ratio, are analyzed and compared respectively. On this basis, the revision proposals to the shear-gravity ratio in Code of the seismic design of China are put forward.Secondly, in order to make sure the security of structure by using shear-gravity ratio and site adjustment parameter, twelve structures in four modes’ group have been selected to do the time-history dynamic analysis in Preform-3D software. After getting the results of time-history dynamic analysis in three different ways, analyzing the results and making sure the structures are safe in big earthquake.Finally, a representative model was selected to compare the difference of shear-gravity between the two national design specifications of China and the United States.