A numerical study on the cumulative out‐of‐plane damage to church masonry façades due to a sequence of strong ground motions

Abstract

Summary Seismic shocks occur sometimes as a sequence, close in space and time, of destructive events of comparable intensity. In these cases, a significant portion of the damage to historical buildings can be related with the cumulated damage on structures that become progressively more vulnerable. This research investigates the specific increase of damage determined by a sequence of strong ground motions, focusing the interest on the out‐of‐plane response of 2 church masonry façades. The dynamic analyses were performed by a specific rigid body and spring model RBSM, which only accounts for out‐of‐plane damage mechanisms. Two idealized models of façade, each made of 2 different masonry bonds, have been studied by applying various sequences of recorded accelerograms. The results highlighted a complex relationship between the spectral content of the seismic shocks and the characteristics of the structures that change in the course of the loading sequence due to the development of damage. The Housner spectral intensity proved to be a reliable scalar measure of the ground motion destructiveness for these façades. Moreover, when considering a design‐consistent accelerogram that causes a relevant damage pattern, ie, with a significant elongation of the effective first period of vibration, the numerical results indicated a possible spectral intensity threshold below which the occurrence of repeated seismic shocks, both before and after the reference design shock, can be considered as irrelevant. On the other hand, a catastrophic increase of damage should be expected when this threshold is overcome.

Seismic response of a masonry church in Central Italy: the role of interventions on the roof

“…This additional moment is evaluated assuming a shear stress on the infill-block interface equal to the residual cohesion of the infill. Once the masonry leaves are uncoupled, the vertical hinge response is a function of the shear stress state in the mortar interfaces (Casolo 2017), which considers the vertical compression due to self-weight. For the twisting springs, an average of the bending spring laws is considered, as validated in (Casolo and Milani 2013).…”

Effect of Uncertainties in Material and Structural Detailing on the Seismic Vulnerability of RC Frames Considering Construction Quality Defects

“…Various levels of ground motion of magnitudes (M w ) 5-6 and hypo-central distances of 5-60 km were selected as tabulated in Table 2. Note that spectral intensity (SI) is defined by Housner as the integral of the pseudo-velocity spectra over the period range from 0.1 to 2.5 s [22]. Figure 6 shows the response acceleration spectra of selected records, which are evenly distributed from 0.01 g and 2.00 g at the fundamental period of the reference structure.…”

Numerical insights on the seismic behavior of a non-isolated historical masonry tower

“…As anticipated, the tower has been subjected to two big shocks (May 20th and 29th). Indeed, a sequence, close in space and time, of strong shocks of similar intensity can induce damage cumulation in the masonry structure, which represents a very challenging issue recently investigated by Casolo (Casolo, 2017). For the tower under study, after the first shock, the main tower already presented some cracks of which, unfortunately, only a very poor documentation is available.…”