During the 2011 off the Pacific Coast of Tohoku earthquake (the 3.11 main shock), Tokyo metropolitan area was suffered from long period ground motions with long duration generated from widely spread seismic fault rupture in east Japan Sea area. Indoor damages including slippage and overturning of huge furniture and cracks in wallpapers were reported in super high-rise RC buildings. In the metropolitan area, most of these buildings are constructed on soft deposit and supported by pile groups supported by engineering bedrock. Precise estimation of seismic response of piles is also required for the 3.11 main shock and future massive earthquakes, as well as damage estimation for upper structure.
This paper describes dynamic behavior of a super high-rise RC building constructed in Tokyo area mainly focusing on seismic performance of pile group. The 3-D moment-resisting frame model including basement and pile group is constructed for the super high-rise residential building where seismometers are equipped at 3 floors. After the 3-D model is validated by comparison with observed records during the 3.11 main shock, pile stresses are evaluated along with nonlinear responses of the superstructure. Structural responses and pile stresses are also calculated for the 3.11 aftershock and future massive earthquakes focusing on whether the building has experienced the 3.11 main shock or not. Conclusions are summarized as follows;
1) The strong motion records during the 3.11 main shock observed at 3 floors of the target building are well simulated by the nonlinear response analyses for the 3-D moment-resisting frame model with piles by using records at pile tip level as the input motion. Pile stresses have not reached to yielding stress level during the 3.11 main shock.
2) Bending moments at pile heads under assumption of rigid foundation beams are larger than those for beams considering their flexibility. On the other hand, differences between two are smaller than those in the previous studies, because footing beam depth in the target super high-rise building is larger than that for low or middle-rise buildings.
3) The observed records during the 3.11 aftershock were well simulated by temporarily consecutive seismic response analyses after the 3.11 main shock, rather than independent analysis. Pile stresses during the 3.11 aftershock were also overestimated for temporarily independent seismic response analyses, because of the overestimation of upper structural responses resulting in increase of the inertial force applied at pile heads.
4) Structural response and pile stresses are estimated for the future scenario earthquakes, the Nankai Trough earthquake and the northern Tokyo Bay earthquake, focusing on experience of the 3.11 main shock. If the input level of the future earthquake is smaller or almost equal to that the 3.11 main shock, estimation of piles stresses could be different for experience of the 3.11 main shock due to difference of the inertial forces.
