Issue 48

V. M. G. Gomes et alii, Frattura ed Integrità Strutturale, 48 (2019) 304-317; DOI: 10.3221/IGF-ESIS.48.30 307 proposed to represent non-preloaded bolted joints often used in rack structures and often called as snug-tight bolted joints. Fig. 1 shows the experimental setup used to perform the slip tests, its respective scheme and the dimensions of the tested specimens. In addition, the geometry data were listed in order to evaluate the influence of geometry and hole locations on failure modes. Tab. 2 shows the geometric parameters used and Fig. 2 illustrates them. D hole parameter corresponds to the plate hole diameters, e 1 the end distance, e 2 the edge distance and p 1 and p 2 the distances between centres of holes. Tab. 2 summarizes the series of specimens that were tested for two preloads and 3 repetitions (12×2×3=72 tests), where the first letter in specimen reference is related to the type of test (S-static), the second letter is the type of connection (S-single; M-multiple), the third letter is the type of coating (C-uncoated, Z- zinc coated and P-zinc coated plus painted); lastly, the numbers 2 or 3 in specimens reference are related to plate thickness in mm. Figure 2 : Definition of symbols used in characterization of bolted joints geometry: A) 1+1 bolted joint, B) 4+4 bolted joint. Specimen Thickness Width D hole e 1 e 2sup e 2inf p 1 p 2 SSC2 2.00 80. 00 18.03 35.01 40.00 - - - SSC3 2.89 80.06 17.97 34.96 40.04 - - - SSZ2 2.07 80.02 18.08 34.97 40.01 - - - SSZ3 3.03 80.08 18.05 34.64 40.04 - - - SSP2 2.50 80.30 17.65 34.94 40.15 - - - SSP3 3.32 80.13 17.60 34.50 40.06 - - - SMC2 2.06 130.01 17.90 34.94 40.06 40.12 50.01 50.07 SMC3 3.09 129.98 17.97 34.97 40.09 40.09 50.02 50.04 SMZ2 2.10 130.10 18.00 35.05 40.11 39.86 49.81 50.02 SMZ3 3.09 130.23 17.95 35.08 40.25 40.01 49.99 50.08 SMP2 2.40 130.32 17.65 35.02 40.18 40.15 49.82 49.95 SMP3 3.31 130.40 17.57 34.86 40.31 40.22 49.70 49.95 Table 2 : Average dimensions (mm) of the test series (refer to Fig. 2 for nomenclature). Besides the static tests, monotonic slip tests were also performed in accordance to the EN1090-2 standard [8]. The main goal of the slip tests was to evaluate the slip factors for three surface conditions mentioned before and the comparison of the obtained slip factors with static friction coefficients estimated by load-displacement curves obtained in monotonic static tests. The chosen parameters for the slip tests were: one preload level (70% of bolt ultimate tensile resistance, Fu ) and the three surface conditions already mentioned. A total of five repetitions for each type of surface finishing were performed, resulting in 15 slip tests. According to EN 1090-2 standard, the slip factors shall be evaluated for a sliding load correspondent to 0.15mm measured with LVDTs. LVDTs with a stroke limit of +/-5mm were used to evaluate the relative displacement between the exterior and interior plates of the joints. Fig. 3 shows the experimental setup used to perform the slip tests, its respective scheme and the dimensions of the tested specimens. The experimental setup is composed by two blocks fixed on middle plates, which support four LVDTs (two LVDTs per block) and two stop plates D hole e 2 sup e 1 A D hole e 2 sup e 1 e 2 inf p 1 p 2 B