Issue 35

P. Bernardi et al, Frattura ed Integrità Strutturale, 35 (2016) 98-107; DOI: 10.3221/IGF-ESIS.35.12 105 0 50 100 150 200 250 300 350 400 0 2 4 6 8 10 Vecchio-Shim beam Bresler-Scordelis beam NLFEA P [kN] δ [mm] OA1 0 50 100 150 200 250 300 350 400 0 5 10 15 20 25 30 35 40 Vecchio-Shim beam Bresler-Scordelis beam NLFEA P [kN] δ [mm] OA3 0 50 100 150 200 250 0 1 2 3 4 5 6 Podgorniak-Stanik beam NLFEA P [kN] δ [mm] BN25 BN25D 0 50 100 150 200 250 300 350 0 1 2 3 4 5 6 7 8 9 Pogdorniak-Stanik beam NLFEA P [kN] BN50 δ [mm] BN50D Figure 4 : Comparison between experimental and numerical results in terms of applied load vs. midspan deflection for specimens (a) , (b) of the OA series [17], and (c) , (d) of the BN series [18]. w f-max = 0.40 mm w f-max = 0.43 mm w f-max = 0.30 mm w f-max = 0.47 mm w f-max = 0.35 mm w f-max = 0.49 mm OA1 OA2 OA3 w [mm] Figure 5 : Experimental (left side, [17]) vs numerical (right side) crack patterns and crack widths at failure for specimens OA. Further comparisons between numerical and experimental results are also provided in terms of cracking development and crack widths, as depicted in Figs. 5 and 6. Fig. 5 shows the crack pattern at failure for the three specimens tested by Vecchio and Shim [17]. As can be observed, the model exhibits a fine capability of reproducing the experimental diagonal- tension crack, catching the very brittle and sudden failure typical of beams containing no shear reinforcement. Furthermore, maximum crack widths, which represent one of the most difficult parameter to predict in numerical analyses, are substantially comparable to experimental ones. Similar results have been also obtained for RC beams tested by Podgorniak-Stanik [18]. More attention has been here devoted to the analysis of crack pattern evolution for increasing