Seismic damage assessment of unanchored nonstructural components taking into account the building response

Abstract

The paper presents an extended seismic damage assessment of unanchored nonstructural components by means of rigid block analysis. Both (real) ground and floor motions are considered as loading histories, together with accelerogram inputs developed according to the latest protocols for shake table testing of (acceleration-sensitive) nonstructural components (AC156 and FEMA 461). A performance-based methodology is developed for the damage analysis of the components, also taking into account magnification and filtering actions of reinforced concrete buildings. Fragility curves are evaluated, and the influence of the key parameters on the seismic performance of rocking components is characterized. Floor motions are found to be more severe than (strong) ground motions, except for large blocks under moderate to overturning rocking amplitude (considering ground acceleration-based intensity measures). Strong floor motions are significantly more severe than (strong) ground motions, and they are associated with a relatively reduced record-to-record uncertainty. AC156 protocol produces inputs overall compatible with floor motions, whereas FEMA 461 protocol inputs are more severe and fit better strong floor motions. The severity of the record sets is found to be correlated with the frequency content of the loading histories. The study provided new knowledge and technical insights regarding the seismic damage assessment of unanchored (building) components.