Seismic performance evaluation of VCFPB isolated storage tank using real-time hybrid simulation

Variable curvature friction pendulum bearings (VCFPB) effectively reduce the dynamic response of storage tanks induced by earthquakes. Shaking table testing is used to assess the seismic performance of VCFPB isolated storage tanks. However, the vertical pressure and friction coefficient of the scaled VCFPB in the shaking table tests cannot match the equivalent values of these parameters in the prototype. To avoid this drawback, a real-time hybrid simulation (RTHS) test was developed. Using RTHS testing, a 1/8 scaled tank isolated by VCFPB was tested. The experimental results showed that the displacement dynamic magnification factor of VCFPB, peak reduction factors of the acceleration, shear force, and overturning moment at bottom of the tank, were negative exponential functions of the ratio of peak ground acceleration (PGA) and friction coefficient. The peak reduction factors of displacement, acceleration, force and overturning moment, which were obtained from the experimental results, are compared with those calculated by the Housner model. It can be concluded that the Housner model is applicable in estimation of the acceleration, shear force, and overturning moment of liquid storage tank, but not for the sliding displacement of VCFPBs.