Seismic assessment and qualification of acceleration-sensitive nonstructural elements through shake table testing: Reliability of testing protocols and reliability-targeted safety factors

Shake table testing represents the best option for assessing and qualifying acceleration-sensitive nonstructural elements (NEs). Several testing protocols are defined in regulations and codes and implemented in the literature, but no commentaries or literature studies provide information regarding the expected reliability or recommend applicative safety factors. The study investigates the seismic reliability of shake table testing protocols for seismic assessment and qualification of acceleration-sensitive NEs. Numerical analyses are carried out considering an incremental procedure and modeling NEs as inelastic single degree of freedom (SDOF) systems, over a wide range of frequencies of interest and NE structural properties. Real floor motions recorded in instrumented reinforced concrete (RC) buildings are considered as a reference. The reliability is estimated considering several damage states and various floor motion sets. In particular, the seismic capacities associated with the real (shake table protocol) floor motions are considered as actual-demand (nominal-capacity) measures, and the demand to capacity margin is meant as the protocol overestimation of the NE capacity. In the light of the estimated protocol reliability, reliabiliy-targeted capacity safety factors are assessed, and applicative factor abaci and closed-form criteria are proposed.