Precast frame structures are widely used in Europe for single-story buildings devoted to industrial production in areas exposed to seismic hazard. Proper design and detailing of these structural systems can guarantee a dynamic behavior characterized by large flexibility and significant displacement capacity. However, recent earthquakes showed that a strong interaction occurs between the structural frame and the cladding panels, due to the inadequate decoupling of their typical connection systems. Recently, the design of precast structures including their cladding panels has been framed within a European project named SAFECLADDING. New solutions have been introduced, including isostatic systems able to effectively decouple the seismic response of frame and panels. This thesis aims to evaluate the seismic risk of precast concrete frame industrial structures with cladding panels investigating the seismic behavior of the full assembly with different isostatic panel connection systems. The investigated panel connection systems are: a) pendulum, b) cantilever, and c) rocking. The case of cantilever panel system has been studied with two models, with and without the effect of friction sliding force under multiaxial load. The probabilistic-based structural response has been assessed based on the results of static nonlinear analysis and multi-stripe dynamic nonlinear analyses carried out with the OpenSees software on numerical models characterized by lumped plasticity. Demand over capacity curves allow for a direct comparison of the influence of the different panel connection systems on the seismic performance of the assembly. Based on the demand over capacity curves, reliability assessment of each structural system has been carried out for two limit states, ultimate and damage. Seismic risk assessment has been carried out on a typical precast structure assembly considering three different sites in Italy. For each site and structural system, ten hazard levels characterized by mean return period ranging from 10 up to 100000 years have been considered.
Le strutture a telaio prefabbricate sono diffusamente utilizzate per edifici monopiano a destinazione industriale in tutta Europa, incluse aree sismiche. Il comportamento sismico di tali strutture è caratterizzato da elevata flessibilità e, con progetti e dettagli opportuni, da elevata capacità di spostamento e comportamento duttile. Ciononostante, recenti terremoti hanno mostrato che una forte interazione sismica avviene tra la struttura a telaio ed i suoi pannelli di tamponamento. A causa dell'inadeguato disaccoppiamento offerto dai tipici dispositivi di connessione, numerosi pannelli sono collassati. La progettazione sismica di strutture prefabbricate con pannelli di tamponamento è stata recentemente inquadrata nell'ambito del progetto Europeo di ricerca SAFECLADDING. Sono state proposte nuove soluzioni, inclusi sistemi di connessione dei pannelli isostatici in grado di disaccoppiare efficacemente la risposta sismica di telaio e pannelli. Il presente elaborato di tesi ha come obiettivo la valutazione del rischio sismico associato a strutture prefabbricate a telaio con pannelli di tamponamento e lo studio dell'influenza di diversi sistemi di connessione dei pannelli sul comportamento sismico dell'assieme strutturale. I sistemi di connessione studiati sono: a) pendolo, b) mensola, c) basculamento (rocking). Il caso del sistema a mensola è stato studiato in due configurazioni, considerando o meno l'effetto dell'attrito di scorrimento per carichi multidirezionali. La risposta strutturale di una tipica struttura prefabbricata caratterizzata dai tre sistemi di connessione oggetto di studio è stata valutata mediante analisi statiche e dinamiche non lineari attraverso la modelli numerici a plasticità concentrata sviluppati con il software OpenSees. I diagrammi domanda/capacità ottenuti permettono un confronto diretto di come i diversi sistemi di connessione influenzano il comportamento sismico dell'assieme strutturale. Valutazioni di affidabilità strutturale e rischio sismico sono state sviluppate per stati limite di danno e di collasso e rispetto a tre differenti siti in Italia sulla base di dieci livelli di intensità sismica con periodi medi di ritorno da 10 a 100000 anni.
Seismic risk assessment of precast frame structures with cladding panels
GAJERA, KRUNAL
2017/2018
Abstract
Precast frame structures are widely used in Europe for single-story buildings devoted to industrial production in areas exposed to seismic hazard. Proper design and detailing of these structural systems can guarantee a dynamic behavior characterized by large flexibility and significant displacement capacity. However, recent earthquakes showed that a strong interaction occurs between the structural frame and the cladding panels, due to the inadequate decoupling of their typical connection systems. Recently, the design of precast structures including their cladding panels has been framed within a European project named SAFECLADDING. New solutions have been introduced, including isostatic systems able to effectively decouple the seismic response of frame and panels. This thesis aims to evaluate the seismic risk of precast concrete frame industrial structures with cladding panels investigating the seismic behavior of the full assembly with different isostatic panel connection systems. The investigated panel connection systems are: a) pendulum, b) cantilever, and c) rocking. The case of cantilever panel system has been studied with two models, with and without the effect of friction sliding force under multiaxial load. The probabilistic-based structural response has been assessed based on the results of static nonlinear analysis and multi-stripe dynamic nonlinear analyses carried out with the OpenSees software on numerical models characterized by lumped plasticity. Demand over capacity curves allow for a direct comparison of the influence of the different panel connection systems on the seismic performance of the assembly. Based on the demand over capacity curves, reliability assessment of each structural system has been carried out for two limit states, ultimate and damage. Seismic risk assessment has been carried out on a typical precast structure assembly considering three different sites in Italy. For each site and structural system, ten hazard levels characterized by mean return period ranging from 10 up to 100000 years have been considered.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/146505