Methods for defining the seismic loadings of liquid storage tanks: an experimental comparison

摘要

Storage tanks are essential structures but there is no explicit procedure to scale ground motions for time-history analysis of liquid storage tanks. Current standards and design codes minimise the difference between the response spectra of the chosen records and the target spectrum in a range of periods central to the response of a tank. The limits of the period range are related to the fundamental translational period in the direction being considered. However, the design specifications have important differences in scaling procedures that may affect the seismic response of the structure analysed. Additionally, these procedures were not specifically formulated for performing time-history analysis of storage tanks whose fundamental period is generally much shorter than other structural types. This paper reports on a series of experiments, using a shake table, of a model PVC tank that contains water. A comparison is presented of the seismic response of a fixed base system (tank with anchorage) by using the procedures of three codes in international use to determine the applicable time history of loading. The experiments were performed using ground motions recorded from the Christchurch sequence of earthquakes. Measurements of the stresses in the tank shell are presented. The main differences between the scaling procedures and the consequences are discussed.