Milone, Aldo (2023) On the Performance of Lap-Shear Hot-Driven Riveted Connections: Experimental and Numerical Study. [Tesi di dottorato]

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Abstract

Hot-driven riveted connections are one of the most common structural details adopted for existing metal structures built prior to the ‘60s of the XXth Century. Nowadays, several existing riveted constructions are still in service and usually exhibit structural deficiencies, owing to both i) a significant increase of acting loads with respect to erection time and/or ii) the lack of detailed provisions in earlier normative codes. The present work is hence devoted to study the static and fatigue performance of lap-shear riveted connections accounting for their peculiarities. After a initial state-of-the-art review dealing with i) manufacturing technology, ii) past significative applications, iii) peculiar issues, iv) normative provisions and v) previous literature studies related to hot-driven riveted connections, in this work some refined predictive models for the static and fatigue resistance of connections are proposed, calibrated and preliminarily validated. To this end, advanced damage formulations and fatigue analysis techniques are adopted to account for peculiarities of riveted connections. For instance, both the effects of hot-driving process and stress concentrations nearby geometrical discontinuities are properly accounted as described in dedicated Sections. Relevant model parameters have been calibrated against the results of three comprehensive experimental campaigns. The first set of tests, which was carried out in collaboration with Norwegian University of Science and Technology (NTNU), aimed at validating energetic approaches for fatigue assessment of blunt notched components made of mild steels. The second set of trials, which was previously carried out by the Candidate’s Research Group, was devoted to parametrically inspect the static behaviour of different lap-shear riveted connections accounting for the influence of i) hammering process and ii) specimens’ geometrical features. The most recent experimental campaign aimed at parametrically investigating the fatigue performance of a second set of identical hot-driven connections. Each experimental set-up and experimental outcomes are illustrated in detail in relevant Sections of the present work. Based on a careful revision of obtained results, semi-empirical formulations are finally derived and compared with normative requirements reported in EN1993:1-8 & EN1993:1-9. Finally, the effect of common constructional imperfections (i.e. the so called “camming” defects induced by plates misalignment) on the static performance of hot-driven riveted connections is preliminarily investigated and discussed. Eventually, main conclusive remarks and possible further developments of the present research activity are summarized at the end of this work.

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