The reliability of analyses of historical structures is affected by the large uncertainties in the characterization of construction and material properties as well as structural systems. Thus, nondestructive investigations play a fundamental role in the assessment of historical structures minimizing, at the same time, the invasiveness of interventions. Among non-destructive testing techniques, Operational Modal Analysis (OMA) is very popular and has wide applicative perspectives. The present paper discusses its role with reference to the assessment of an Italian heritage site, the Carthusian Monastery of Trisulti. Attention has been first focused on the use of OMA for the identification of the fundamental periods of the historical bell tower of the Saint Bartolomeo's church. The fundamental period, in fact, plays a primary role in the definition of the expected earthquake loading on the structure. The second case study, instead, concerns the tests carried out on a number of tie-rods in the central cloister in order to indirectly estimate the tensile load in these members. An innovative system for in-situ non-destructive estimation of the tensile load in tie-rods is described. It takes advantage of an original algorithm for automated OMA and of a high performance measurement chain. This is able to resolve the low amplitude vibrations of the tie-rods in operational conditions without modifying their dynamic response. This result is obtained through the installation of high-performance, low-weight and high sensitivity accelerometers. The algorithm for automated OMA is described in its most relevant aspects and the obtained results are presented, pointing out the stability of the estimates.

The role of Operational Modal Analysis in the non-destructive assessment of an Italian monument

RAINIERI, Carlo;GARGARO, Danilo;FABBROCINO, Giovanni
2015-01-01

Abstract

The reliability of analyses of historical structures is affected by the large uncertainties in the characterization of construction and material properties as well as structural systems. Thus, nondestructive investigations play a fundamental role in the assessment of historical structures minimizing, at the same time, the invasiveness of interventions. Among non-destructive testing techniques, Operational Modal Analysis (OMA) is very popular and has wide applicative perspectives. The present paper discusses its role with reference to the assessment of an Italian heritage site, the Carthusian Monastery of Trisulti. Attention has been first focused on the use of OMA for the identification of the fundamental periods of the historical bell tower of the Saint Bartolomeo's church. The fundamental period, in fact, plays a primary role in the definition of the expected earthquake loading on the structure. The second case study, instead, concerns the tests carried out on a number of tie-rods in the central cloister in order to indirectly estimate the tensile load in these members. An innovative system for in-situ non-destructive estimation of the tensile load in tie-rods is described. It takes advantage of an original algorithm for automated OMA and of a high performance measurement chain. This is able to resolve the low amplitude vibrations of the tie-rods in operational conditions without modifying their dynamic response. This result is obtained through the installation of high-performance, low-weight and high sensitivity accelerometers. The algorithm for automated OMA is described in its most relevant aspects and the obtained results are presented, pointing out the stability of the estimates.
2015
9788461738809
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11695/48350
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