Experimental Study on Seismic Behavior of Liquid Storage Tanks Subjected to Vertical Earthquakes

Abstract

Previous studies on seismic performance of large-scale liquefied natural gas (LNG) storage tanks mainly focused on the horizontal earthquake excitations. However, vertical earthquake actions may lead to structural damage, overturning and even failure of a liquid storage tank, especially under near-fault earthquakes. In this study, aiming to investigate seismic behavior of the inner tank of a large-scale LNG storage tank subjected to vertical earthquakes, a shaking table test of a 1:25 scaled steel tank with full-filled liquid was carried out. Vertical components of El Centro waves, Chi-Chi 1529 waves and Chi-Chi 1505 waves were selected as input, representing near-field earthquakes, near-fault earthquakes without and with vertical velocity pulse, respectively. Seismic responses, including the sloshing wave height, hydrodynamic pressure and stress on the tank wall were obtained and analyzed. Results showed that the sloshing wave height under Chi-Chi waves was 1.2 ~ 2.5 times larger than that under El Centro waves. In comparison with El Centro waves with the peak ground acceleration (PGA) of 0.26 g, the peak hydrodynamic pressure increased by 10 and 36% under Chi-Chi 1529 waves and Chi-Chi 1505 waves, respectively. In addition, the vertical velocity pulse contained in near-fault earthquakes significantly amplified the stress on tank wall. For instance, the hoop and axial stress were increased by 269.12 and 63.50% at most under the excitations of Chi-Chi 1529 waves, respectively. Dynamic responses of liquid under vertical near-fault earthquakes were greater than that under near-field earthquakes, especially under the near-fault earthquakes with vertical velocity pulse.