Experimental and analytical study on ground motion characteristics under structure cluster disturbance

Abstract

AbstractSoil‐structure cluster dynamic interaction (SSCI) has a significant effect on structural responses as well as ground motions for soft soil, while investigations on the latter remain limited. In this paper, four test models, including the free field model, soil‐single structure model, soil‐equal height structure cluster model, and soil‐multiple height structure cluster model, were manufactured and investigated through large scale shaking table tests. The effect of structure numbers, layouts, structural dynamic characteristics and seismic spectrum characteristics on the ground motions was discussed. On this basis, finite element analysis and wavelet packet decomposition were employed to further investigate the evolution rule of cluster effect. The results manifested that, due to the structure cluster, the predominant period of the original free field could be elongated notably and earthquake response spectrum in the long period domain was amplified, especially under the excitation of seismic waves with abundant low‐frequency components. The influence of SSCI on ground motions is chiefly reflected in the variation of site predominant period and the soil damping during the vibration. In addition, the cluster effect on ground motion presents a monotonous degressive trend with the increase of the structural spacing, and its attenuation rate is negatively correlated with structural height, while the difference in ground motion due to different structure numbers becomes insignificant with the increase of structural spacing.