Issue 51

M.G. Masciotta et alii, Frattura ed Integrità Strutturale, 51 (2020) 423-441; DOI: 10.3221/IGF-ESIS.51.31 436 Figure 13: Experimental (left) and numerical (right) mode shapes for Reference Scenario with Weight RSW (blue line: front side A01- A13; red line: back side A14-A26). Damage scenarios simulation Using the FE model calibrated through the standard model updating sketched in the previous subsection, a linear perturbation followed by modal analysis is conducted via the NOSA-ITACA code according to the procedure described in Section 0, modeling concrete as a linear elastic material, bricks and mortar as masonry-like materials. A further model updating is conducted by keeping the values of E , ν and ρ fixed (Tab.4) and varying the tensile strengths of brick (σ t = 0.5 MPa) and mortar (σ t = 0.37 MPa). In order to numerically reproduce the experimental crack pattern along with its evolution [46], the tensile strength of the mortar joint circled in red in Fig. 10 is reduced of about 80%. Each analysis is conducted by imposing the same horizontal displacements (X direction) recorded during the experimental test to all nodes belonging to the base of the right abutment (moving support). As an example, the comparison between numerical and experimental results for DS3 and DS5 is summarized in Tab. 7 and Tab. 8, highlighting percentage frequency errors and MAC values between corresponding vibration modes. A visual comparison between experimental and numerical mode shapes for damage scenarios DS3 and DS5 is given in Figs 14 and 15. DS3 f exp f num | Δ f |[%] MAC (  exp,  num ) Mode 1 21.45 22.13 3.17 0.97 0.00 0.00 0.01 Mode 2 45.14 48.96 8.46 0.01 0.80 0.00 0.00 Mode 3 58.27 53.24 8.62 0.05 0.00 0.79 0.07 Mode 4 74.97 73.32 2.20 0.09 0.00 0.01 0.88 Table 7 : Experimental ( f exp ) versus numerical frequencies ( f num ), frequency relative error Δ f and MAC matrix for DS3.