Issue 51

M. Pepe et alii, Frattura ed Integrità Strutturale, 51 (2020) 504-516; DOI: 10.3221/IGF-ESIS.51.38 510 Example 5 (61 blocks) is a slender panel with two vertical openings and finally Example 6 (146 blocks) represents a bigger panel characterized by four openings positioned on two different levels. Each block of the structures is subjected to dead load 0 f and a live load L f , proportional to the collapse multiplier, acting towards right direction. Moreover, in both FEM and FEM/DEM simulations, the elastic constants (i.e. Young’s modulus and Poisson’s ratio) for masonry units are 20 E GPa  and 0.15   . The additional nonlinear parameter for FEM simulations, appearing in Eqs. (1.4) and (1.5), are: max 0 0.001 T T  , 0 T being the average compressive stress associated with the dead load; 0.001 nc sc B     . B being the width of full-size blocks. It is worth noting that these values have been adopted in the subsequent numerical simulations in order to represent the dominant frictional behavior of dry joints, as stated in previous section. Finally, the penalty constant is set as 1000 p K E B  , i.e. sufficiently high to avoid significant interpenetrations between adjacent units. Fig. 4 refers to results obtained for Example 1. The mechanism is characterized by a hinging behavior with the rotation of the upper right corner of the panel. Limit Analysis and FEM present also the formation of two ‘stair-stepped’ crack not detected by the FEM/DEM which on the contrary provide also a sliding of the blocks not observed in the results of the other two techniques. Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Figure 3 : Geometrical configurations of the panels analyzed by Ferris and Tin-Loi (a) (b) (c) Figure 4 : Collapse mechanism for Example 1, horizontal live load: ( a ) ALMA 2.0, ( ) FEM/DEM, ( ) FEM