Sliding fragility of block‐type non‐structural components. Part 1: Unrestrained components

Abstract

SUMMARYMotivated by the development of performance-based design guidelines with emphasis on both structural and non-structural systems, this paper focuses on seismic vulnerability assessment of block-type unrestrained non-structural components under sliding response on the basis of seismic inputs speciÿed by current seismic codes. Two sliding-related failure modes are considered: excessive relative displacement and excessive absolute acceleration. It is shown that an upper bound for the absolute acceleration response can be assessed deterministically, for which a simple yet completely general equation is proposed. In contrast, fragility curves are proposed as an appropriate tool to evaluate the excessive relative displacement failure mode. Sample fragility curves developed through Monte-Carlo simulations show that fragility estimates obtained without taking into account vertical base accelerations can be significantly unconservative, especially for relatively large values of the coe cient of friction. It is also found that reasonable estimates of relative displacement response at stories other than the ground in multistorey buildings cannot in general be obtained by simply scaling the ground acceleration to the peak acceleration at the corresponding storey. Failure modes considered in this study are found to be essentially independent of each other, a property that greatly simpliÿes assessment of conditional limit states.

Shake table testing of museum display cases

“…Past research has indicated that the sliding motion is sensitive to the frequency content of its input excitation (Augusti et al 1992;Lopez Garcia and Soong 2003). Our results indicate that the intensity of input acceleration increased from level 1 to level 2 by 22% on average, while the sliding displacements increased on average by 85%.…”

Effect of Nonlinearity of Frame Buildings on Peak Horizontal Floor Acceleration

“…An important step in estimating the vulnerability of acceleration sensitive NCSs and thus improving their probability of survival, is to estimate the expected peak horizontal floor acceleration (PHFA) distribution within the buildings housing these components as accurately as possible. Subsequently, knowledge of PHFA can be used to assess the seismic vulnerability of NCSs via seismic fragility curves, which are derived from damage data, if available, or experimental and/or numerical simulations [e.g., RayChaudhuri and Hutchinson, 2005, Lopez-Garcia and Soong 2003aBadilloAlmaraz et al, 2007]. Therefore, a better prediction of PHFA leads to a better design or retrofitting strategy for anchoring, supporting, or bracing the NCS.…”

Seismic response of sliding equipment and contents in base‐isolated buildings subjected to broadband ground motions

“…Sliding is very common for freestanding (i.e., unrestrained) EC, particularly those that are stocky and have a relatively low friction coefficient. The problem of sliding objects has been studied at various levels by Shao and Tung , Choi and Tung , Lopez Garcia and Soong , Chaudhuri and Hutchinson , Hutchinson and Chaudhuri , Konstantinidis and Makris , and references reported therein. The concern for sliding EC is excessive displacements, which can lead to different problems depending on the type of EC.…”