Figure 18. Failure panel mechanisms: (a1,a2) RAN method, (b) SAM method; (c) 3MURI method.

This one storey building is made by yellow tuff masonry 30 cm thick and cementicious mortar. The plan dimensions are 7.60 x 7.50 m2 for an height of 3.0 m. The foundation system consists of the same walls deepening into the ground, and the roof structure consists of two slabs: an external gable roof and an internal attic, both in reinforced concrete and holed bricks. A weight density of 16 kN/m3 was assumed for masonry and the following loads were deduced at the moment of the quake (Table 2). The soil was type C (according to O.P.C.M. n. 3431).

The panel discretization, according to the three methods, is shown in Figure 17. Apparently, RAN foresees two geometrical models for the two verses of the horizontal action; 3MURI and SAM models give the same model independently from the verse.

In Figure 18 the failure mechanisms of the panels are shown.

The pier panel on the left fails for eccentrical load according to the three methods. In fact, as illustrated in Figure 16, horizontal cracks appeared at the superior and inferior extremities.

The panel in the middle fails for tensile shear stress, as also performed by the analytical estimation. The pier shows two diagonal cracks starting from plasticized zones. The shape of the cracks suggests that the first wave came from the right and the second one from the left, since this second crack stops at the intersection with the first one.

Figure 18. Failure panel mechanisms: (a1,a2) RAN method, (b) SAM method; (c) 3MURI method.

Figure 19. Capacity curves: comparison (a) Positive horizontal actions; (b) Negative horizontal actions.

Finally, combined flexural and axial load provoked the crisis of the last panel on the right, immediately followed by shear for horizontal actions from right to left.

Therefore, it can be stated that the methods correctly evaluate the crisis typologies.

Then the capacity curves obtained from a non linear static analysis, according to the two verses of the seismic actions, were compared (Fig. 19).

From these capacity curves it can be noted that RAN and 3MURI provide almost similar stiffness and force values only in the case of verse action from right to left (when the central pier panel is considered in its whole height, as really happened). Conversely, SAM method turns from the previous ones due to the impossibility of modelling the irregularity in a one storey building.

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