Shaking Table Tests on the Effect of U-Shape Dampers on a Liquid Storage Tank Isolated by Multiple Friction Pendulum Bearings

Isolation bearing has exhibited good performance on reducing seismic responses of liquefied natural gas (LNG) storage tanks under earthquakes. However, large displacement of the isolation layer may come into scene under near-fault earthquakes, especially under that contain long-period velocity pulses. Employing supplemental damping in the isolation systems is an effective method to control the displacement of isolators. This paper aimed to investigate the effect of U-shape dampers on an inner steel tank isolated by multiple friction pendulum bearings (MFPB) under El Centro waves and Chi-Chi 1529 waves. The hysteretic behaviors of MFPB, MFPB with Mg–Al alloy dampers and MFPB with mild steel dampers were firstly evaluated by quasit-static cyclic tests. Then, shaking table tests were conducted on a 1:25 scaled steel tank model with and without isolation bearings. Results showed that the U-shape dampers could be used to effectively control the displacement of the isolators. The peak displacement of MFPB decreased by 18% ~ 28% and 8% ~ 17% after equipping with Mg–Al alloy and mild steel dampers respectively under Chi-Chi 1529 waves.