Effects of Strong Ground Motion with Identical Response Spectra and Different Duration on Pile Support Mechanism and Seismic Resistance of Spherical Gas Holders on Soft Ground

Mio Kobayashi,Toshihiro Noda,Akira Asaoka,Toshihiro Takaine,Kentaro Nakai

doi:10.3390/app112311152

Abstract

Safety measures are required for spherical gas holders to prevent them from malfunctioning even after a large earthquake. In this study, considering the strong nonlinearity of the ground and damage to the pile during an earthquake, a three-dimensional seismic response analysis of the holder–pile–ground interaction system was conducted for an actual gas holder on the soft ground consisting of alternating layers of sand and clay. In the analysis, the seismic response of the structure to strong ground motions of different durations with the same acceleration response spectrum was verified. The results show that the piles were relatively effective in controlling the settlement when the duration of the earthquake motion was long. This is because the axial force acting on the pile increased due to the redistribution of the holder load caused by the lowering of the effective confining pressure of the sand and clay layers during the earthquake, which increased the bearing capacity of the pile. In contrast, when the duration of the seismic motion was short, the piles had little effect on the reduction in the settlement because the maximum acceleration was higher than that in the former case, and the piles immediately lost their support function.

Highlights

Spherical gas holders (“holders”) in Japanese gas companies have been constructed since the 1950s, and there have been no confirmed cases of damage caused by earthquakes
These holders must be verified to be able to withstand collapse during level-2 (L2) strong ground motion earthquakes
It is considered effective with regards to the deformation performance of the pile foundation and ground to verify the seismic resistance of the coupled holder–pile–ground system, which considers the non-linear response of the ground during strong earthquakes and the damage limit of the pile based on this

Summary

Introduction

Spherical gas holders (“holders”) in Japanese gas companies have been constructed since the 1950s, and there have been no confirmed cases of damage caused by earthquakes. All the piles were damaged in several places, and all support functions were almost completely lost immediately after the earthquake; it was shown that the amount of settlement of the holder during and after the earthquake was almost equivalent to the case when the pile was not assumed to be present These evaluations set input seismic motions with a short duration corresponding to near-field earthquakes according to the JGA guidelines, which determined the seismic motion according to the installation point of the holder. By utilizing the seismic verification carried out in this study, the holders can continue to function even after a large-scale natural disaster, thereby minimizing the damage to the economy and society without causing catastrophic damage, as is the case with earthquake countermeasures for industrial lifeline and equipment [21]

Analysis Conditions

Ground Modeling

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