NONLINEAR ROCKING ANALYSIS OF NUCLEAR REACTOR BUILDINGS : Simultaneous Horizontal and Vertical Earthquake Inputs

Centrifuge Tests of Impulsive Vertical Acceleration Generated by Foundation Uplift During Strong Shaking

“…Considering the fact that the measured vertical acceleration of the superstructure was almost equal to that of the footing for Cases ER and ES, the vertical velocity of the superstructure for Case NR was assumed to be equal to that of the footing, the average vertical velocity of the footing's left and right sides. The impulse value shows a fairly good agreement with the momentum value, conˆrming that the vertical acceleration of Type B is actually caused by the collision impulse between the footing and the soil, as numerically predicted by Meek (1975) and by Muto and Kobayashi (1979). The vertical acceleration of Type B will herein be called thè`i mpulsive vertical acceleration''.…”

“…This caused downward accelerations varying within the footing. Vertical acceleration is called``induced vertical acceleration'', and it is generated by the movement of the gravitational center of the structure following the uplift of the footing (Muto and Kobayashi, 1979;Tomura et al, 1988;Shiomi, 2006). In Types BL and BR, without any horizontal inertial force from the superstructure, larger upward accelerations with the same amplitude developed throughout the footing.…”

“…Huckelbridge and Clough (1978) reported that the loading impulses do not signiˆcantly aŠect the story shear or the base-overturning moment. Based on a numerical analysis of reactor buildings subjected to both horizontal and vertical input motions, Muto and Kobayashi (1979) indicated that foundation uplift could induce two types of vertical acceleration, namely, collision impulse by foundation uplift and induced vertical acceleration by the height movement of the gravitational center of the structure. Furthermore, the former could be larger in acceleration amplitude than the latter.…”

Centrifuge Testing and Seismic Response Analysis for Uplift Behavior of Spread Foundation Structures on Rock

“…For the seismic design of a nuclear power plant, analytical studies on non-linear rocking behavior have been conducted [e.g., Muto and Kobayashi (1979), Yamada and Kawamura (1984), Shimomura (1988), Yano et al (1991), and Nakamura et al (2016)]. Moreover, experimental studies using shaking table or centrifugal tests have been conducted [e.g., Yano et al (1983), Hangai et al (1986Hangai et al ( , 1987, Ishikawa et al (2007), Imamura et al (2014), and Imamura et al (2013)].…”