Seismic behaviour of rubble masonry: Shake table test and numerical modelling

Abstract

The destruction of Amatrice and the surrounding villages in Central Italy after the 2016 seismic sequence was so impressive that engineers, authorities and local communities started sharing the common feeling that historical stone masonry buildings were too below current safety standards. The severe damage caused by the earthquakes led to a general distrust of traditional building techniques, leading to the conclusion that there is nothing to do but demolish and rebuild, perhaps with a false antique. Is there an alternative? Is there a way to combine safety and preservation of architectural heritage? This paper aims contributing to the understanding of the seismic behaviour of stone masonry by reproducing, through simulation on a shake table, the progressive loss of compactness of a real scale rubble masonry wall up to the ruinous collapse with the separation between the two external leaves. The laboratory simulation allowed to evaluate the decrease of the fundamental frequency with increasing damage and estimate the maximum displacement profile and the amount of cracking that the wall is able to sustain before failing. Eventually, two modelling strategies based on finite and discrete element methods were proposed and applied to verify the capability of simulating the out-of-plane seismic response and the failure mechanisms of rubble masonry.

Detecting Damage Evolution of Masonry Structures through Computer-Vision-Based Monitoring Methods

“…This is reflected in the higher values attained by the DI prior to collapse, which in both cases took place during the 1.4 scaled series, resulting in the fall of stones from the upper portion of the wall. The frequency decay and the damage accumulation measured through the proposed technique result are consistent with the damage observed on the walls during the experimental investigations, as described in [21,22]. In particular, the unreinforced wall reached its ultimate limit state by exhibiting an out-of-plane bending collapse mechanism of the two wall leaves.…”

“…The three wall specimens tested on the shake table had the same dimensions of 0.5 m thickness, 3.73 m height, and 1.63 m width. They were built on reinforced concrete beams using rubble stone units and weak lime mortar, resembling the typical characteristics of the masonry type surveyed in the villages in Central Italy, which suffered heavy damage during the destructive earthquake sequence in 2016-2017 [21]. One wall was tested as it was, and the other two walls were reinforced adopting different strengthening techniques, both characterized by relatively low invasiveness and consisting of a preliminary injection with consolidating mortar.…”

An Expeditious Tool for the Vulnerability Assessment of Masonry Structures in Post-Earthquake Reconstruction

“…The seismic performance of an unreinforced masonry structure highly relies on its capacity to exhibit a box-type behaviour, which depends on the load transfer effectiveness at the intersections between orthogonal walls. On the contrary, insu cient connection leads to the separation between walls, especially of the perimeter ones, and promotes their out-of-plane overturning, which is one of the most frequent (and dangerous) seismic failure modes experienced by unreinforced masonry structures (Lourenço et al, 2011;de Felice et al, 2022).…”

Non‐linear dynamic model of a two‐bodies vertical spanning wall elastically restrained at the top

“…The quality of the masonry plays an essential role in the type and in the magnitude of damage following an earthquake. The masonry must have adequate quality to resist horizontal actions and to transfer vertical loads at the same time and the structure, or parts of it, must have a monolithic behavior, otherwise masonry disintegration may occur 2 . The OOP behavior of a wall significantly changes if it is connected to horizontal structural elements (Figure 1A).…”

“…The masonry must have adequate quality to resist horizontal actions and to transfer vertical loads at the same time and the structure, or parts of it, must have a monolithic behavior, otherwise masonry disintegration may occur. 2 The OOP behavior of a wall significantly changes if it is connected to horizontal structural elements (Figure 1A). The collapse, in this case, could take place for slipping/failure of the diaphragm or for overturning of the wall, following the formation of a crack at an intermediate height between the base and the top as observed after earthquakes in several countries.…”