Fragility and risk assessment for sliding artifacts in artifact-showcase-museum systems subjected to three-component ground motions

Abstract

Vertical ground motions may increase irregularity of sliding response, while the subsequent impact on the sliding fragility of building contents is not clear. Moreover, seismic risk of structural collapse contributes to the total sliding risk of building contents, while it is usually ignored. This paper first introduces a seismic fragility and risk assessment method for the sliding artifact in the artifact-showcase-museum (ASM) system subjected to three-component ground motions. In this method, the square roots of the sums of the squares of peak ground accelerations and peak sliding displacements in two orthogonal horizontal directions are implemented as the intensity measurement and the engineering demand parameter, respectively. Incremental dynamic analysis using the nonlinear three-dimensional finite element model of the ASM system is performed to generate seismic fragility curves of sliding artifacts. The total sliding risk of the artifact is estimated as the sum of the sliding risk of the artifact on the premise of no structural collapse and the structural collapse risk. Then, the seismic fragility and risk of the sliding artifacts within a four-story frame structure and an existing museum is assessed when the systems are subjected to three-component ground motions, respectively. Effects of vertical ground motions, freestanding and restrained showcases, floor levels, sliding thresholds, structural collapse and different structures on the sliding fragility and risk of the artifact are investigated. Results show that the influence of vertical ground motions on the sliding fragility of artifacts in different structures may be significant or marginal depending on the ratios of peak vertical to horizontal floor acceleration. Moreover, the artifact in the freestanding showcase is less fragile than that in the restrained showcase regarding sliding failure. Furthermore, neglecting the structural collapse risk and estimating the sliding risk of the artifact by not removing the structural collapse data would underestimate the total sliding risk of the artifact.