A. Teramo

FDTD modelling in high-resolution 2D and 3D GPR surveys on a reinforced concrete column in a double wall of hollow bricks

A structural characterization of a reinforced concrete column in a double wall of hollow bricks, carried out within diagnostics testing through 2D and 3D high-frequency GPR surveys and aimed at the evaluation of the seismic vulnerability of a building is proposed. It highlights how the use of FDTD simulation allows the limits of these surveys to be overcome, with reference to the difficulty of the processing and interpretation steps in order to identify rebars beyond the hollow bricks. Their reflection pattern, being complex, makes it very hard to recognize the rebars placed parallel to the brick hollow axis direction.

Application for Capacitively Coupled Resistivity Surveys in the City of Messina

The electrical surveys by means of the OhmMapper Geometrics were carried out in the urban centre of the Messina city. The obtained results show an increased level of vulnerability of sediment areas due to the reduced depth of the water table in zones close to the coastline, also according to the hydrogeological characteristics of the urban area, which is crossed by nine seasonal streams. An additional safety reducer was highlighted by the presence of large area of the city where the buildings, also strategic buildings, have foundation partially or totally immersed in ground water table or water leakage from the municipal water. The CCR measurement can therefore be a useful supplement during the delineation of groundwater protection areas in urban sites where the telluric noise and the very dry shallow layer make the more traditional galvanic method impracticable. The main advantage of CCR is a more simple experimental setup, which allow a deeper insight into underground structure and results in a more time and cost effective geoelectrical logging.

On the Characterization of a Geophysical Diagnostics Resolution Index within the Seismic Damage Scenario Construction

A methodological approach for selecting areas to be subjected to geophysical diagnostic is proposed to determine the damage susceptibility of territory elements within the construction of a seismic damage scenario for the city of Messina. The morphology of the urban context have made difficult the programming and execution of those geophysical surveys more consistent with the objective to be achieved. On the basis of different indicator typologies, an empirical relationship has been established to identify the territory elements of a higher significance where to focus a greater diagnostic commitment for the acquisition of specific data to be used for seismic vulnerability assessments at a large scale. To this end it was defined a diagnostic resolution index, related to the specific characteristics of the territorial system, stands out as a significant interest element in the study and evaluation of the regional multi-hazard conditions (shallow water-table, presence of debris of buildings referable to the past earthquakes, high level of heterogeneity of the lithotypes, the widespread presence of surface faults, ...) The analysis of preliminary results have made possible the assessment of the reliability of the proposed procedure in order to properly planning a diagnostic campaign related to the safety reducers of the area in study.