Abstract

Dynamic monitoring is a well-established technique used to gain information on the global health of constructions. In particular, ambient vibration tests have achieved important results in the dynamic characterization of modal parameters. Several techniques and instrumentations are currently available, however the accuracy of these results is often unquestioned. The mutual validation between different modal analysis techniques is an important procedure to assess the reliability of the results. In the present paper the ambient vibration tests performed on the so-called ‘Temple of Minerva Medica’ in Rome considering different techniques and instrumentations will be described and compared. While it is referred to as the Temple of Minerva Medica, the structure is actually a ruined decagonal nymphaeum in opus latericium that dates to the 4th century AD. Today, the construction is located between the main central train station (Roma Termini) and the local tram way. Ambient vibration data were acquired during different campaigns [1] to characterize the effects of the vibrations and the modal parameters of the structure. This work deals with the data collected on the 11th of July 2019 within the project “Tecnologie per il miglioramento della Sicurezza e la ricostruzione dei centri Storici in area sismica” coordinated by DTC Lazio (Distretto Tecnologico beni e attività culturali). The instrumentation comprised of several seismographs equipped with triaxial velocimeters and piezoelectric accelerometers. A variety of techniques were applied to process the acquired vibration data in order to extract the modal parameters of the studied structure including PolyMAX, FDD, EFDD, CC-SSI, HVSR and FRF. Comparison of the modal parameters obtained by each different technique was considered to provide indications on the reliability of the instruments.

Abstract

Traditional architecture made of timber-framed masonry (TFM) system is widespread around the world and has already been recognized as a unique cultural heritage to be preserved. These structures have shown a good seismic performance compared to other typologies because their configuration and construction details were constantly updated as soon as the builders addressed the causes of damage mechanisms when earthquakes occurred. Regarding this typology, Romanian TFM structures can be considered a representative example also because they experienced several seismic events showing their good earthquake-resistance. Although these buildings are still constructed and inhabited nowadays, no recommendation is provided in the Romanian building code and its structural behaviour is not properly characterized yet. Bearing in mind that the building’s global response depends on many parameters such as the performance of its structural elements and their interaction, the calibration of shear walls is crucial to define the non-linear behaviour under cyclic loading. A simplified modelling strategy was chosen to simulate TFM wall response consisting of an equivalent frame with linear elastic elements and non-linearities lumped at the joints by using OpenSees. After calibrating the wall response according to the experimental campaign performed at Technical University of Civil Engineering of Bucharest, the panel was adapted to model a representative Romanian TFM building whose dynamic properties were evaluated by eigenvalue analysis and their potential calibration is proposed based on the ambient vibration tests.