The thesis introduces the reader to the world of explosives used in civil or industrial fields, therefore we want to give a quick overview of the most recurrent types of explosives used in a terrorist attack to hit a structure. Before tackling the problem of protecting strategic buildings or particularly vulnerable to possible attacks by explosive devices (as the seat of authoritative exponents of the Italian judiciary involved in the fight against the mafia), the functioning of the explosive phenomenon with its consequent risks is explained. The second and third part of the thesis aims to diagnose the most effective and used systems to protect an existing or newly built civil structure from a shock wave produced by a certain explosive charge placed at a distance from the target (standoff). In these two parts are explained methods and techniques for reinforcing each structural element and any material commonly used in constructions. The thesis wants to prove the efficiency of FRP composite materials to increase the resistance to explosions as well as the permissible deformability before collapse. In the fourth part of the thesis, ample space is given to the experimental report on the subject: through the use of the FEM calculation code Abaqus CAE, the behavior under an increasing explosive load of a reinforced concrete plate was studied by comparing it with the same structural element reinforced by two layers of FRP. Therefore, the research wants to explain the modeling used in the elastic and inelastic field with particular regard to the Drucker Prager criterion implemented in the software and the problem of modeling the interactions between the types of finite elements adopted is also addressed. Finally, the structure is subjected to an explicit dynamic analysis adopted to simulate explosive problems.
La tesi riguarda l’esplosivistica utilizzata in ambito civile o industriale, dando una rapida panoramica delle tipologie più ricorrenti di esplosivi utilizzati sia a fini utili, ad esempio per la demolizione controllata, sia in casi quali gli attentati terroristici contro le strutture. Prima di affrontare il problema della protezione di edifici strategici o particolarmente vulnerabili a possibili attacchi di ordigni esplosivi (come le sedi della magistratura italiana impegnata nella lotta alla mafia), si spiega il funzionamento del fenomeno esplosivo con i suoi conseguenti rischi. La seconda e terza parte della tesi ha l’obiettivo di studiare i sistemi più efficaci ed utilizzati per proteggere una struttura civile, esistente o di nuova costruzione, da un’onda d’urto prodotta da una certa carica esplosiva posta ad una distanza dal target (standoff). Vengono presentate le metodiche e le tecniche per rinforzare ogni elemento strutturale ed ogni materiale di comune utilizzo in edilizia e si evidenzia l’efficienza dei materiali compositi in FRP per aumentare la resistenza alle esplosioni oltre che la deformabilità ammissibile prima del collasso. Nella quarta parte della tesi, attraverso l’uso del codice di calcolo agli Elementi Finiti Abaqus CAE, si studia il comportamento sotto un carico esplosivo crescente di una piastra in calcestruzzo armato confrontandolo con lo stesso elemento strutturale rinforzato da due strati di FRP, quale esempio caratteristico di applicazione. E' stato affrontato il problema della modellazione delle interazioni tra le tipologie di elementi finiti adottati, e si sono illustrate le tipologie di analisi adottate per simulare problemi esplosivi, ovvero, le analisi dinamiche esplicite.
SIMULAZIONE NUMERICA DELL'EFFICACIA DEI RINFORZI IN FRP PER LA PROTEZIONE DELLE STRUTTURE IN CALCESTRUZZO ARMATO DALLE ESPLOSIONI
COVIELLO, CRISTIANO GIUSEPPE
2021/2022
Abstract
The thesis introduces the reader to the world of explosives used in civil or industrial fields, therefore we want to give a quick overview of the most recurrent types of explosives used in a terrorist attack to hit a structure. Before tackling the problem of protecting strategic buildings or particularly vulnerable to possible attacks by explosive devices (as the seat of authoritative exponents of the Italian judiciary involved in the fight against the mafia), the functioning of the explosive phenomenon with its consequent risks is explained. The second and third part of the thesis aims to diagnose the most effective and used systems to protect an existing or newly built civil structure from a shock wave produced by a certain explosive charge placed at a distance from the target (standoff). In these two parts are explained methods and techniques for reinforcing each structural element and any material commonly used in constructions. The thesis wants to prove the efficiency of FRP composite materials to increase the resistance to explosions as well as the permissible deformability before collapse. In the fourth part of the thesis, ample space is given to the experimental report on the subject: through the use of the FEM calculation code Abaqus CAE, the behavior under an increasing explosive load of a reinforced concrete plate was studied by comparing it with the same structural element reinforced by two layers of FRP. Therefore, the research wants to explain the modeling used in the elastic and inelastic field with particular regard to the Drucker Prager criterion implemented in the software and the problem of modeling the interactions between the types of finite elements adopted is also addressed. Finally, the structure is subjected to an explicit dynamic analysis adopted to simulate explosive problems.I documenti in UNITESI sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/20.500.14253/85915