Pentangelo, Vincenzo (2010) SEISMIC ASSESSMENT OF SUSPENDED CEILING SYSTEMS. [Tesi di dottorato] (Unpublished)
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|Item Type:||Tesi di dottorato|
|Uncontrolled Keywords:||Nonstructural components; fragility curves; seismic performance; suspended ceiling systems; required response spectrum; limit states; shake tables; time history acceleration; spectrum matching procedure; random vibrations|
|Date Deposited:||13 Dec 2010 17:36|
|Last Modified:||30 Apr 2014 19:44|
Non-structural components in most types of commercial building represent a major portion of the total cost of the building and, as such, will represent a large portion of the potential losses to owners, occupants, and insurance companies. Non structural components may be classified in three broad categories: architectural components, mechanical and electrical equipment, and contents. Non-structural components play a fundamental role about safety of human lives during seismic events: in fact the collapse of suspended light fixtures, hung ceilings or partition walls; the plunging onto the ground of failed cladding panels, parapets, signboards, ornaments, or glass panels; the overturning of heavy equipment, book-shelves, storage racks, or pieces of furniture; and the rupture of pipes or containers with toxic materials are all capable of causing serious injury or death. In this work seismic performance of suspended ceiling systems has been analyzed by plotting fragility curves obtained through real scale tests. In particular seismic assessment of suspended ceiling systems is carried out by performing shake table tests: in fact being ceilings elements not amenable to structural analysis, full-scale testing is the only feasible possibility to develop fragility curves. In particular single and double frame ceilings are tested on simulator platform (a 3m × 3m square table and two orthogonal horizontal degree of freedom system). The input to the table is provided through artificial time histories accelerations representative of expected/target ground motion and acting simultaneously along the two orthogonal directions of the platform simulator; these time histories are selected with the aim of matching the target or required response spectrum of non structural components. Three limit states are used in this study to characterize the seismic response of suspended ceiling systems, both single frame and double frame, and in particular: occupancy limit state (10% damage), damage limit state (30% damage) and safety limit state (50% damage). From the first to the third one limit state considered, the damage in the ceiling increases: in fact when performing a damage analysis with fragility curves, the response is characterized as function of a damage state. Limit states are considered to be reached starting from visual detection of post-test condition of the specimen; indeed, at the end of shaking of each step in a test cycle, research team investigates accurately the physical conditions of components of ceilings in order to identify which limit state has been reached.
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