| Budget Amount *help |
¥10,600,000 (Direct Cost: ¥10,600,000)
Fiscal Year 1999: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1998: ¥6,000,000 (Direct Cost: ¥6,000,000)
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| Research Abstract |
With a view to incorporate the interaction between soil and structure without using any physical ground model, Konagai et al. (1997〜1998) introduced a new method for shaking table tests. In their method, appropriate soil-structure interaction motions are added to free-field ground motions to simulate soil-structure interaction effects. The method considers radiation damping which, in general, causes the total damping of a soil-structure system to be greater than that of the structure itself, Thus the incorporation of soil-structure interaction effects in a shaking table test leads to reducing the demands on the capacity of shaking tables. This dynamic interaction is a phenomenon associated with the influx and efflux of energy which is generated by the earthquake excitation and transmitted through the soil-structure interface. It is noted that the difference between the influx and efflux is exactly the energy stored up within a structure, and thus, is closely related to the extent of da
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mage to the structure. If these interaction effects are rationally simulated in shaking table tests, one will obtain the necessary pieces of information for interpreting the failure processes of prototype structures in terms of energy.
The method was initially developed with the assumption that soil behaves linearly in the present report, the method is extended to take the 'far field' soil non-linearity into account through an equivalent linear approach. The non-linearity produced in the vicinity of foundations, which is usually associated with large strain and separation between soil and foundation, has not been considered in this study. In this method the dynamic soil parameters are varied in real time by means of a digital signal processor. The method, on one hand, captures the non-linear soil behavior of softening and re-hardening during the course of an earthquake, and on the other hand, allows testing of a bigger superstructure model by obviating the need of a heavy physical ground model. Less
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