Possibility of response control of foundation-superstructure system considering dynamic soil-structure interaction during strong earthquakes

点击翻译按钮获取中文摘要

Field investigation after recent earthquakes has shown that damage to foundations and superstructures located in similar soil profile could vary. For example, some foundations were damage without significant damage to their superstructures, while some superstructures collapsed without significant damage to their foundations. Such a difference in damage might have been induced partly by the effects of soil-pile-structure interaction and suggests that the effects of dynamic soil-pile-structure interaction should be properly taken into account in seismic design to mitigate damage to superstructure response and pile stresses. In this study, therefore, centrifuge model tests, large shaking table tests, and numerical analysis were conducted, to estimate dynamic soil-pile-structure interaction in various seismic loading conditions and to investigate possibility of new foundation systems. The test results and analysis have shown that (1) The combination of earth pressure, friction and inertial … More force is affected by the relation between foundation displacement and ground displacement, the height of non-liquefied crust layer, and the relation of natural period of superstructure and ground; (2) The subgrade reaction within a pile group in non-liquefied ground is larger in the leading piles than in the following piles, while that in liquefied ground is larger in the outside piles than the inside piles. As a result, the horizontal load is the largest in the leading piles in non-liquefied ground but in the outside piles in liquefied ground; (3) Buckling stress is estimated by buckling length, soil stiffness and support condition. The slenderness ratio proposed in this study corresponds to that indicated in the guideline for steel structures; (4) Not only soil-pile-structure response but also pile stress is affected such parameter as; predominant period of input motion, natural periods of superstructure and ground, occurrence of liquefaction, presence of foundation embedment. The foundation embedment decreases the pile stresses in non-liquefied ground but increases pile stresses in liquefied ground. Less