Evaluation of soil-building resonance effect in the urban area of the city of Matera (Italy)

Abstract

This study discusses the effect of buildings vibrations in the urban field in the context of local seismic response studies in order to evaluate the possible occurrence of double resonance effects during strong-motions. The aim is to recognise the interaction effect between near surface geology and all overlying buildings in the urban area of the city of Matera (southern Italy). Single station seismic ambient noise measurements (230) were performed on the main lythologies (134) and on the principal building typologies (96). Soil and building measurements allowed estimating the main frequencies and relative amplitudes of the soil fundamental peaks as well as the first vibrational frequency of buildings. The period-height linear relationship, derived by experimental results, made it possible estimating the fundamental frequency for all the Matera's buildings. Having also estimated the frequencies at each point of the urban soil it was thus possible to obtain a soil-building resonance map in the linear elastic domain. Matera represents an important case study because the first vibration frequency for most of the buildings is quite close to those of the foundation soils. About 21% of buildings show high probability of occurrence of soil-building resonance effect, about 63% of the buildings are characterised by a medium resonance level, while about 16% are at zero or very low level. The proposed approach makes it also possible to identify the areas of the city characterised by these different probabilities of resonance levels.