The central disaster management council of the cabinet office and ministry of land, infrastructure and transport predicted strong motion which is considerably huger than conventional assumption. In base-isolated buildings, collision with retaining wall is concerned, recently experimental and analytical study done. Nonlinear characteristics of superstructure and characteristics response of laminated rubbers has been reported so far. In order to grasp ultimate states of base-isolated building, continued study is required. In this paper, under these circumstances, with the aim of response evaluation of laminated rubbers in case of collision with retaining wall, especially its vertical response, studied factors which have an influence on seismic response.
Factors we studied in this paper are nonlinear characteristics of superstructure and laminated rubbers, and soil-structure-interaction. Change of overturning moment caused by nonlinear characteristics of superstructure affects vertical response. In case of considering the response of laminated rubbers in large deformation, it is desirable to consider horizontal-vertical interaction of laminated rubbers. Moreover, it is expected that the influence of Soil-Structure-Interaction (SSI) increased, because the excitation on vertical direction due to pulling out laminated rubbers. According to above background, this paper describes the investigation results by numerical simulations, which evaluate the vertical response of laminated rubbers in case of collision with retaining wall under considering these factors. Target building is seven story base-isolated building which we have been observing and studying, and input motion is a simple pulse wave. As a result, the following conclusion are obtained.
(1) In order to study influence of horizontal vertical interaction of laminated rubbers, compare calculation result between Basic model and MS model. In horizontal response, there is not effects about differences in modeling, however in vertical response of laminated rubbers, vertical displacement of MS model is 1.7 times at the maximum in comparison with the Basic model because of decrease vertical stiffness of MS model.
(2) In horizontal direction, maximum acceleration of superstructure reduce by SSI, the reduction effects correspond with height of soil spring constant. In vertical direction, the maximum vertical displacement of the laminated rubber reduce about 66% at the maximum compared with base-fixed.
(3) In order to analyze the reduction factor of vertical response due to SSI, separate rocking vibration and vertical vibration from vertical response time history. In case of base-fixed, rocking vibration increased by collision with retaining wall, especially after 5Hz but these reduced by vertical of SSI.
(4) Considering the non-linearity of superstructure, the vertical response of laminated rubbers is decreased. This effects is greatest among the three factors we studied, but if strength of superstructure is high, it is necessary to perform appropriate modeling for the effect of soil-structure interaction.
