Study on the seismic mitigation effects of inerter isolated storage tanks

Abstract

Liquefied Natural Gas (LNG) storage tanks can ensure national energy sufficiency, but they are vulnerable to earthquakes. Although ordinary seismic isolation bearings can effectively reduce the base shear force and overturning moment, they tend to amplify the height of the sloshing wave. In this paper, a hybrid vibration control method for LNG storage tanks is proposed, paralleling the series viscous mass damper (SVMD) devices with Lead-core rubber bearings (LRB). The seismic mitigation effects of this parallel seismic isolation scheme were investigated. First, three-dimensional finite element models of fixed base, LRB isolated and SVMD isolated tanks were established, and nonlinear time history analyses were performed for the three types of tanks to compare the seismic responses. It was concluded that SVMD can effectively control the sloshing wave height. In addition, the effects of site types, storage liquid heights, and SVMD's performance parameters on the seismic mitigation effects were also studied. It was found that the softer the site soil, the higher the storage liquid height would make seismic isolation less efficient. The increase of SVMD's additional equivalent mass reduces the sloshing wave height, increases the shear-to-weight ratio, and has little influence on the base displacement. The increase of SVMD's additional equivalent damping reduces the sloshing wave height, base shear force, and base displacement of the tank. The final conclusion is that SVMD can effectively control the sloshing wave height and has a good seismic mitigation effect.