Experimental study of slip-friction connectors for controlling the maximum seismic demand on a liquid storage tank

Abstract

Previous investigations have demonstrated that strong earthquakes can cause severe damage or collapse of storage tanks. Theoretical studies by other researchers have shown that using energy-dissipating anchors can reduce the axial compressive stresses in the tank shell compared to the fully anchored case. Those studies have also shown that using energy-dissipating anchors can reduce the displacement of the tank compared to the unanchored case. However, there is no experimental work to validate the results obtained from these numerical studies. This paper reports on a series of experiments using a shake table on a scale model PVC tank containing water. A comparison of the seismic behaviour of a fully fixed base system (tank with anchorage), a system free to uplift (tank without anchorage) and a partially fixed system (tank with slip-friction connectors) is presented. The slip-friction connectors are calibrated by performing cyclic tests. The experiments were performed using recorded ground motion scaled to the New Zealand design spectra for two Wellington sites. Measurements were made of the axial compressive stresses in the tank shell and the horizontal displacement of the top of the tank. The experiments showed the beneficial effects of using slip-friction connectors in storage tanks, reducing the uplift displacement in comparison with an unanchored tank and reducing the axial stresses compared to a fully fixed tank. A numerical model is proposed which corroborates these results.