GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 2.2 GNGTS 2023 The case study of the colonnade The case study is represented by the arcade gallery shown in Fig. 1. This is composed of ten arches supported by monolithic stone columns, with stone capitals, and by lateral masonry buttresses. The roof is simply-supported and transmits the dead load through the reaction forces of the main supporting beams. On the opposite side, the roof is resting on a stiff and rigid wall, parallel to the colonnade. The adopted densities for the materials forming the structure, i.e., tuff bricks for masonry, stone for columns and capitals, wood and clay tiles for roof, are reported in Tab. 1, which also records the density adopted for transparent glass-based bracing. Note that the density for the roof beams is much higher than that of wood, because it takes into account the secondary beams and roof tiles. To consider a real example of old masonry, with realistic imperfections, the brick stereotomy and the geometry of the arcades are borrowed from the colonnade inside the Duomo di Casertavecchia (Caserta, Italy), for which a detail laser-scanner survey was available. We restrict our attention at the in-plane response of the colonnade (seismic ground motion along x direction in Fig. 1). Because of the presence of the fornices (voids), the colonnade results to be much more compliant than the parallel solid wall. Hence, the structural stiffness is unevenly distributed with respect to the gravitational supported mass from the roof. Moreover, inside the colonnade, structural stiffness is further unevenly distributed, since the columns would respond as hinged rods and the seismic actions would concentrate on the lateral, much stiffer, buttresses. On the one hand, the colonnade would be subjected to large oscillations under the seismic action, thus shearing and damaging the roof; on the other hand, at the level of the colonnade, the buttresses would be highly stressed and strained, probably exceeding their deformation capacity, possibly loosing equilibrium under rocking motion. On the whole, the colonnade would need additional stiffening members to withstand the ground movement and avoid high damage or eventual collapse. Fig. 1. Geometry of structure considered as a case study: masonry colonnade as built, characterized by a wooden simply-supported roof and a background wall, with indication of main dimensions [m] and the position of reference brick for the plot of results.