Abstract
Damage-imperfection indicators based on variation of dynamic parameters allow to identify the intrinsic discontinuity and the damage of structures. Here, the structural health monitoring through the vibration-based approach has been carried out by two steps on three different multileaf masonry specimens (full infill, damaged infill, and strengthened infill) subjected to uniaxial compressive load. In the first step, the characterization of initial conditions based on the investigation of the intrinsic discontinuity and the manufacturing imperfections has been done. In this phase, the detection, localization, assessment, and prediction of damage have been given by the comparison between the experimental and numerical modal data calculated by the commercial finite element code. Subsequently, in the second step, starting from the identification of undamaged condition, the damage effects on changes of the dynamic parameters have been recorded. As well known, the incoherent response between the leaves is related to frequency values, damping ratios, and modal shapes.
Highlights
Damage identification methods based on vibration responses have been used for the monitoring of steel or concrete structures, such as long bridges or tall buildings, where the relative homogeneity of materials or the structural typology are suitable for vibration analysis
Shock and Vibration and to their possibility of not providing direct access to the damaged zone, which may be very important in case of natural disasters such as seismic events [8,9,10,11,12]. e adoption of combined historical and architectural surveys together with dynamic investigations allows realizing reliable numerical models able to describe the actual behavior of cultural heritage and, in case of alteration of the vibration response, to identify possible damage or imperfections and to predict future structural behavior [13, 14]
Laboratory tests have been proposed to improve methodologies for dynamic identification and damage detection of existing masonry structures, both on full-scale masonry buildings [15] and on masonry wall panels [16, 17], with attention focused on damage indicators
Summary
Flexural and Compressive Tests on Mortar Samples. For the laboratory tests on mortars, specimens were prepared in accordance with the EN 1015-11. Tests were performed for determination of flexural strength. FF is the maximum load of the flexural test, while FC is the maximum load of the compressive tests; in detail, ft flexural strength, Mortar type CP/5 TD13C TD13SRG. After the experimental tests on mortars, compressive tests were performed on brick specimens. Nine specimens were prepared in accordance with UNI EN 1052-3 and subject to the load application in the Galdabini universal testing machines (200 kN) to analyze the initial shear strength. E tests were performed according to the process B (UNI EN 1052-3), which does not include the prestress condition of the samples. Nine specimens were prepared in accordance with UNI EN 1052-3 and subject to the load application in the Galdabini universal testing machines (200 kN) to analyze the initial shear strength. e tests were performed according to the process B (UNI EN 1052-3), which does not include the prestress condition of the samples. e results are reported in Table 2, and all the specimens presented the type of failure A1
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