PSI - Issue 62

Annarosa Lettieri et al. / Procedia Structural Integrity 62 (2024) 789–795 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Table 1. Geometrical properties of the investigated riveted lap shear joints.

Acronyms

Configuration N°

Rivet/hole diameter d (mm)

Plate thickness t / width w (mm)

N° specimens

rivets

S-19-12-1-w90 S-22-10-1-w70 S-22-12-1-w70 U-19-10-2-w60 S-22-12-2-w70 U-22-12-2-w70

Symmetric Symmetric Symmetric

1 1 1 2 2 2

19 22 22 19 22 22

12/90 10/70 12/70 10/60 12/70 12/70

2 1 1 1 1 2

Unsymmetric

Symmetric

Unsymmetric

3.2. Prior literature data Experimental data from former fatigue tests have been collected from the literature and statistically analysed. All data refer to lap shear joints tested with a constant stress amplitude in the high-cycle regime. Specifically, Parola et al . (1965) present the results of an experimental campaign in which riveted connections were tested under zero-to tension, complete reversal and half-tension-to-full tension loading conditions (respectively corresponding to stress ratios R equal to 0, -1. 0.5). These specimens were designed to study the effect of the bearing ratio (ratio between the bearing pressure on the rivet hole and the net stress range) on the fatigue resistance of riveted assemblies. Besides, aiming to capture the effect of the clamping forces on the fatigue resistance, a group of identical specimens has been investigated in two different conditions: after pressing the rivet head for slightly damaging the shank to reduce clamping forces and with normal clamping, namely without applying alteration after the riveting process. The work outcomes showed the riveting process's beneficial effect on the riveted details' fatigue resistance, highlighting a more uniform stress distribution in the plates around the rivet holes generated by higher compressive forces under the rivets, which increases the friction forces in the connection. Finally, the study highlighted that increased bearing pressure increases the local stresses at the rivet holes with a consequent fatigue strength reduction. Moreover, Correia et al . (2014) and da Silva et al . (2015) investigated the fatigue behaviour of riveted connections from ancient Portuguese bridges (i.e., Eiffel, Luiz I, Fão, Pinhão and Trezòi bridges). Double- and single-shear riveted connections were cut from existing girder or manufactured using the original materials. The fatigue tests used stress ratio ( R ) values equal to 0.01 and 0.1. The experimental results have been statistically analysed and compared with the current fatigue S - N curves, confirming the inadequacy in predicting riveted structural details' fatigue resistance of detail 71 (Kühn et al. , 2008). Additionally, the experimental campaigns included the fatigue characterisation of the base materials, allowing the development of advanced numerical procedures for fatigue assessment. Sire et al . (2020) conducted experimental fatigue tests to study the behaviour of double-shear mono-rivet hot-riveted specimens fabricated using the recovered material from the demolished bridge over the Adour River belonging to the French railway network. The fatigue results have been statistically analysed, confirming the better accuracy of the S - N curves given by Taras et al . (2010). Finally, the experimental data used by Taras et al . (2010) and referring to the experimental tests carried out by Graf O. (1935), Klöppel K. (1936) and Graf O. (1941) on double-shear riveted splices have been included in the present study. A summary of all the experimental results used in this study is reported in Table 2.

Table 2. Collected fatigue test results.

Reference

Specimen type

N° data

Correia et al. , (2014) da Silva et al. , (2015) Parola et al. , (1965) Sire et al. (2020) Taras et al. (2010).

Double- and single-shear 51

Double-shear Double-shear Double-shear Double-shear

19 93 10

63 Experimental investigation Double- and single-shear 8