Shaking table tests on a masonry building monitored using smart bricks: Damage detection and localization

Abstract

Summary The seismic behavior of unreinforced masonry buildings is typically characterized by premature brittle collapse mechanisms that can cause serious consequences for the protection of human lives and for the preservation of historical and cultural heritage. Structural health monitoring can be a powerful tool enabling a quick post‐earthquake assessment of the structure's performance, but its applications are still scarce as a consequence of the severe limitations affecting off‐the‐shelf sensing technologies, in terms of local nature of the measurements, costs, as well as long‐term behavior, installation, and maintenance. To overcome some of these limitations, the authors have recently proposed a new sensing technology, called “smart brick,” that is a durable clay brick doped with stainless steel microfibers, working as a smart strain sensor for masonry buildings. This paper presents the first full‐scale application of smart bricks, used for detecting and localizing progressive earthquake‐induced damage in an unreinforced masonry building subjected to shaking table tests. Smart bricks are employed to detect changes in load paths on masonry walls, comparing strain measurements acquired after each step of the seismic sequence with those referring to the undamaged structure. Experimental results are interpreted using a 3D finite element model built to reproduce the shaking table tests. Overall, the results demonstrate that the smart bricks can effectively reveal local permanent changes in structural conditions following a progressive damage, therefore being apt for earthquake‐induced damage detection and localization.

Strain Monitoring and Crack Detection in Masonry Walls under In-Plane Shear Loading Using Smart Bricks: First Results from Experimental Tests and Numerical Simulations

“…Leveraging the piezoresistive principle, smart bricks, when inserted in masonry structures, can be used to assess variations in strain by monitoring their electrical outputs, such as the electrical resistance. When deployed in coarse sensor networks, smart bricks can be used to monitor permanent changes in strain, e.g., changes due to earthquake-induced damage or differential settlements, by comparing their actual strain measurements with those referring to the undamaged structure [ 39 ]. Smart bricks’ strain outputs can be processed to reconstruct strain fields in masonry constructions/structural elements when the novel sensors are diffusely deployed within the load-bearing systems.…”

“…Accordingly, these innovative brick-like sensors can be embedded within masonry load-bearing structures, giving rise to durable and diffuse SHM systems [ 37 ]. At present, the SHM applications of smart bricks encompass (i) the monitoring of strain in masonry panels tested under compression loads [ 38 ], (ii) the detection and localization of earthquake-induced damage to masonry buildings [ 39 ], and (iii) the strain field reconstruction and damage identification in masonry walls subjected to in-plane loading conditions [ 40 ]. An extensive investigation of the removal of the environmental effects from strain measured by smart bricks was also carried out [ 41 ].…”

Applications of Smart Bricks for Strain Field Reconstruction in Masonry Walls: Numerical Analysis and Shaking Table Tests

“…Recently, full-scale tests and FE modelling simulations, demonstrated their ability to identify damages due to seismic dynamic loads [17].…”

Damage detection via modal analysis of masonry structures using shaking table tests

“…Two models with identical geometry were built, and an experimental investigation was carried out using the shaking table at the ENEA laboratory in Casaccia, Rome, in order to compare the dynamic response of the two different construction types (i.e., URM and CM) to seismic loads. [57][58][59][60] This paper investigates on the effectiveness of vibration-based methods for dynamic identification and damage detection on masonry structures using the experimental data recorded during the shaking table test on the URM and CM models. In particular, the main focus is on the combined use of natural frequencies and associated vibration modes as damage sensitive parameters.…”

“…Recently, the last of these authors started a research program aimed to assess and improve the dynamic performance of masonry structures by using the CM technique. Two models with identical geometry were built, and an experimental investigation was carried out using the shaking table at the ENEA laboratory in Casaccia, Rome, in order to compare the dynamic response of the two different construction types (i.e., URM and CM) to seismic loads 57–60 …”