NUMERICAL AND EXPERIMENTAL INVESTIGATION ON SHEAR BEHAVIOUR OF RIVETED CONNECTIONS
MARMO, RENATA (2011) NUMERICAL AND EXPERIMENTAL INVESTIGATION ON SHEAR BEHAVIOUR OF RIVETED CONNECTIONS. [Tesi di dottorato] (Inedito)
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Hot-driven rivets were extensively used in iron and steel structures in the past. Nowadays, these constructions represent an important part of the architectural and cultural heritage that needs to be preserved and protected. The majority of historic steel structures is still in service and is exposed to loads larger than expected. The reliability of these structures is also affected by deterioration and the poor quality of material (Sustainable bridges 2006). After several decades from their erection, this class of constructions reveals some damages and/or structural inadequacies (Guerrieri et al. 2005). These types of constructions are generally characterized by trussed structural schemes. Hence, the failure of connections can produce the overall failure of the structure, because the riveted connections represent the weaker elements of these structures. These considerations lead to identify the vulnerability of connections as the crucial aspect concerning the structural capacity of ancient metal structures. Hence, the present work is devoted to investigate the structural capacity of lapped riveted connections loaded in shear typically adopted in aged metal structures still in service. The aim is the development of a valid methodology of prevision of the existing riveted connections behaviour. After a preliminary study on the technology of riveted connections and the rivet forming process, and in particular on the effects of hot driven process on the overall behaviour, a review of the actual codes prescriptions is reported, highlighting the approximations in the prescribed verifications and providing to a description of the local phenomena that characterizes the connection behaviour. An overview on the prior research on riveted connections is also presented, in which the experimental studies and the numerical simulations proposed and studied up to today are discussed and described. The literature experimental and numerical studies on riveted connections need to be extended to different materials, geometries and configurations, due to the sensitivity of the connection response to the manufacturing process (Hechtman, 1948; Schenker et al., 1954, Munse, 1970). To this end, a large experimental investigation carried out within the framework of the European project PROHITECH. A detailed description of this campaign is reported: after a detailed illustration of the set-up of experimental tests and of the monitored parameters, the results are presented and discussed. On the basis of a careful revision of results, in the final part of the chapter a theoretical formulation on the failure verifications of these connections is proposed, by revising the EN 1993 1-8 2005 formula. On the basis of the experimental results, a highly detailed riveted connections F.E. model is proposed. The geometries and the mechanical characteristics are described, and contact interactions are illustrated. The element type and the mesh sizing are highlighted, and the rivet clamping model is described. The calibration of the F.E. model is also illustrated. At last, the numerical results are reported and discussed. The work ends with a comparison between numerical and proposed theoretical results to verify the reliability of the theoretical equations and F.E. results. In this manner, a useful tool to predict the behaviour of all types of riveted connections is provided. To this end, the magnitude of numerical results was compared with the proposed theoretical formulas, to ensure both the good accuracy of F.E. model and the reliability of the proposed equations. At last, the main conclusions of the work, together with possible further developments for future research, are illustrated.
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