Seismic Mitigation of Freestanding Artifacts With Mass Filling

Freestanding artifacts are carriers of cultural heritage, and earthquake damage should be avoided as much as possible. Seismic mitigation measures for lowering the center of gravity (CG) by filling a mass have not been well investigated. Using a ceramic vase as a typical artifact object, the correlations between the location of the CG and the filling material were analyzed, and lead beads were determined to be the candidate material for the experimental and analytical investigations. Rectangular rigid block models of the vase with and without mass filling were constructed for rocking analysis. Comparative free-rocking and shaking-table tests were performed on vases with and without mass filling. Mass filling can reduce the coefficient of restitution, free-rocking time duration, and quarter period while increasing the damping ratio. Instrumented earthquake records from a seven-story building were employed in the comparative shake table tests of the vases. The filling mass considerably reduced the rotation and displacement amplitudes compared with those of the empty vase, whereas the reduction in the acceleration amplitude was not as apparent. The experimental and computational results for each test series were identical. Fragility curves were constructed using the shaking-table testing results. Analytical results were obtained utilizing additional instrumented earthquake records experienced by the building. Given the peak floor acceleration, the probability of failure of the filled vase was reduced compared with that of the empty vase. The effect of the story level on the probability of failure was not prominent. This study is advantageous for the seismic mitigation of various freestanding artifacts in buildings and other nonstructural components.