The damage observed during past earthquakes has shown that non-structural elements represent one of the main sources of damage and economic losses. Although the non-structural elements are not generally taken into consideration in the seismic design of buildings, they are subject to the same dynamic actions to which the structural elements are subjected. The present thesis is directed to the study of the seismic demand on non-structural elements installed in the R.C buildings designed according to current normative codes standards. Although some methods have been developed in the last few years to evaluate the floor response spectra and consequently the seismic demand on non-structural elements, none of the methods currently available in the literature takes into account the presence of the infills in the structural mesh for the evaluation of the floor response spectra . However, numerous studies have shown that infills have a considerable influence on the behavior of structures in terms of capacity and natural modes of vibration. On the basis of this consideration, well established in the scientific literature, the present work is directed to the study of the influence of the infills in the evaluation of the floor response spectra. A database consisting in 100 models was created, varying a series of geometric and mechanical parameters of the structures (for example: number of floors, light of the spans and resistance of the concrete). The models were modeled in OpenSees considering both the bare structure and the infilled structure. The structures were analyzed using non-linear dynamic analysis considering different periods of return of the seismic action in order to evaluate their performance and fragility. On the basis of the analyzes carried out, it was possible to create a large database of floor response spectra in order to demonstrate the influence of the infills on them. The results obtained were also compared with the formulations currently available in the normative codes for the evaluation of the forces to be applied to non-structural elements. From the analysis of the results it was found that both the formulations available in the normative codes and the simplified methods available in the literature for the evaluation of the floor response spectra should be appropriately modified to consider the presence of the infills, in particular for low return periods of the seismic action.
I danni osservati durante i passati terremoti hanno messo in evidenza come gli elementi non-strutturali rappresentino una delle principali fonti di danneggiamento e di perdite economiche. Nonostante gli elementi non-strutturali non vengano generalmente presi in considerazione nella progettazione sismica degli edifici, essi sono soggetti alle stesse azioni dinamiche a cui sono sottoposti gli elementi strutturali. Il presente lavoro di tesi è rivolto allo studio della domanda sismica a cui sono soggetti gli elementi non-strutturali installati negli edifici in c.a. progettati secondo gli attuali standard normativi. Nonostante siano stati sviluppati negli ultimi anni alcuni metodi per valutare gli spetri di piano e di conseguenza la domanda sismica sugli elementi non-strutturali, nessuno dei metodi attualmente disponibili in letteratura tiene conto della presenza delle tamponature nella maglia strutturale per la valutazione degli spettri di piano. Tuttavia, numerosi studi hanno dimostrato che le tamponature influenzano in modo considerevole il comportamento delle strutture in termini capacità e modi naturali di vibrazione. Sulla base di questa considerazione, ormai consolidata nella letteratura scientifica, il presente lavoro è rivolto allo studio dell’influenza delle tamponature nella valutazione degli spettri di piano. A tal fine è stato realizzato un database composto da 100 modelli realizzati variando una serie di parametri geometrici e meccanici delle strutture (ad esempio: numero di piani, luce delle campate e resistenza del calcestruzzo). I modelli sono stai modellati in OpenSees considerando sia la struttura nuda che la struttura tamponata. Le strutture sono state analizzate mediante analisi dinamiche non-lineari considerando differenti periodi di ritorno dell’azione sismica al fine di valutarne le performance e la fragilità. Sulla base delle analisi effettuate è stato possibile realizzare un ampio database di spettri di piano al fine di dimostrare l’influenza delle tamponature sugli stessi. I risultati ottenuti sono stati anche confrontati con le formulazioni attualmente disponibili nei codici normativi per la valutazione delle forze da applicare agli elementi non-strutturali. Dall’analisi dei risultati si è riscontrato che sia le formulazioni disponibili nei codici normativi che i metodi semplificati disponibili in letteratura per la valutazione degli spettri di piano dovrebbero essere opportunamente modificati per tenere in conto della presenza delle tamponature, in particolare per bassi periodi di ritorno dell’azione sismica.
Domanda sismica sugli elementi non strutturali: influenza delle tamponature sugli spettri di piano
FARINA, LAURA
2016/2017
Abstract
The damage observed during past earthquakes has shown that non-structural elements represent one of the main sources of damage and economic losses. Although the non-structural elements are not generally taken into consideration in the seismic design of buildings, they are subject to the same dynamic actions to which the structural elements are subjected. The present thesis is directed to the study of the seismic demand on non-structural elements installed in the R.C buildings designed according to current normative codes standards. Although some methods have been developed in the last few years to evaluate the floor response spectra and consequently the seismic demand on non-structural elements, none of the methods currently available in the literature takes into account the presence of the infills in the structural mesh for the evaluation of the floor response spectra . However, numerous studies have shown that infills have a considerable influence on the behavior of structures in terms of capacity and natural modes of vibration. On the basis of this consideration, well established in the scientific literature, the present work is directed to the study of the influence of the infills in the evaluation of the floor response spectra. A database consisting in 100 models was created, varying a series of geometric and mechanical parameters of the structures (for example: number of floors, light of the spans and resistance of the concrete). The models were modeled in OpenSees considering both the bare structure and the infilled structure. The structures were analyzed using non-linear dynamic analysis considering different periods of return of the seismic action in order to evaluate their performance and fragility. On the basis of the analyzes carried out, it was possible to create a large database of floor response spectra in order to demonstrate the influence of the infills on them. The results obtained were also compared with the formulations currently available in the normative codes for the evaluation of the forces to be applied to non-structural elements. From the analysis of the results it was found that both the formulations available in the normative codes and the simplified methods available in the literature for the evaluation of the floor response spectra should be appropriately modified to consider the presence of the infills, in particular for low return periods of the seismic action.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/19783