When a base-isolated building collides with a moat wall, there is a possibility that the building may collide with the moat wall with torsional impact due to the effects of unavoidable eccentricity caused by the performance variation of the seismic isolation devices. However, the effect of torsional impact on building response has been insufficiently studied. This paper reports on the response characteristics and impact force of buildings and moat walls by using analytical models which can evaluate torsional response at each moment.
