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Evaluation of the destructive potential of the 1997-1998 earthquake ground motion in the town of Sellano
Full text linkThe 1997-1998 Umbria-Marche earthquake sequence was characterised by a relatively moderate magnitude (ML = 5-6). Despite that, the earthquake caused extensive damage in different towns, such as in the town of Sellano. Different earthquakes have affected Sellano in the past. In particular, after the earthquakes of 1979 and 1984 most of the buildings of the old centre of Sellano were subjected to intensive seismical remedial works. Nevertheless, many of these buildings suffered significant damage during the 1997-1998 earthquake sequence. The acceleration is widely utilised in seismic routine design; nevertheless, the structure damage analysis and ground motion records obtained in the recent earthquakes indicate a need for the evaluation of other parameters than acceleration to describe the complex relationship between the ground motion and structure damage. The aim of this work is to present new microzonation maps of the PGAPGV ratio, Arias Intensity (Ia,) and destructiveness potential factor (Pd) at the soil surface for the town of Sellano. © 2003 WIT Press
Geotechnical characterization of ash collected during recent eruptions of Mount Etna: from dangerous waste material to environmental friendly resource
No full textAn exponential increase in the activity of Mount Etna (Catania, Italy) has been observed between the massive eruptions that lasted from 1991 to 1993 and the very significant ones, which occurred between 2012 and 2018. Large amounts of ash repeatedly covered the city of Catania, causing environmental problems for road and air traffic, agriculture and human health. Recent thinking has been to consider volcanic ash as a resource rather than a waste material, thus avoiding damage to both the environment and human health. This goal could be achieved using this material in several fields of geotechnical engineering but first static and dynamic laboratory geotechnical tests must be performed. This paper deals with a static and dynamic geotechnical characterization of volcanic ash collected during recent eruptive activity on Mount Etna. Grading and index properties tests, oedometer tests, direct shear tests and dynamic resonant column tests were performed in the Geotechnical Laboratory at the University of Catania. Particle crushing was also analysed following oedometer tests and direct shear tests. The tested materials are essentially of a gravelly-sandy nature and showed very different strains due to the different grain size distribution curves as well as to the aptitude to crushing of these materials. Cohesion is negligible both at peak state and at the critical state, in line with granular soil behaviour. A light curvature of the failure curves can be observed for some peak envelopes. The results of dynamic tests are in quite good agreement with those of well-known sands. Thus, taking into account crushing, it is possible to appropriately reuse these materials in geotechnical engineering avoiding inhalation and ingestio
Large scale soil-foundation-structure model in Greece: Dynamic tests vs FEM simulation
No full textThis paper provides the results of FEM simulation of dynamic tests recently performed in Thessaloniki on a large-scale single-degree-of-freedom structure resting on a soft soil. The structure (named EuroProteas) was specifically designed to mobilize strong soil-structure interaction (SSI), being a particularly stiff structure founded on soft soil. It consists of a simple steel frame with removable X-bracings founded on a RC slab and supporting the superstructure mass of two RC slabs identical to the foundation slab. It is a totally symmetric structure. Subsoil stratigraphy and dynamic properties of the foundation soil are derived from extended geotechnical and geophysical surveys, including static and dynamic in-situ and laboratory tests. Extensive free- and forced-vibration tests were performed. This paper deals with one set of forced-vibration tests. An eccentric mass shaker was used as a source of harmonic excitation (finput = 3, 4.5, 5, 7 Hz and eccentricity 6.93kg-m) imposed on the roof of the structure. The structural response is recorded by seven accelerometers, five of which are located at the top of the roof slab and two at the top of the foundation slab. Soil response is recorded with seismometers installed on the free soil surface in both horizontal directions. Dynamic FEM modelling of the tests were conducted in the time and frequency domains in order to detect the main aspects of SSI, taking into account soil nonlinearity. Numerical and experimental results were extensively compared. Very interesting results were reached above all in terms of the effects of soil-foundation interface behaviour
Geotechnical characterization of Mount Etna ash for its reuse preserving human health
No full textIn the last decades Mount Etna (Sicily, Italy) has partially modified its activity from effusive toeruptive. From the eruption of 1991–1993 to those of 2015 an exponential increasing of its activity has beenobserved. Large amounts of ash have repeatedly covered the city of Catania. This caused problems on the roadand air traffic, agriculture and human health, above all due to the significant toxicity of this material. The storageof Mount Etna ash has become a great problem. The recent trend is not consider the volcanic ash as a waste, butas a resource. Volcanic ash could be particularly used in Geotechnical Engineering, avoiding environmental andhuman health damage. The present paper deals with human health damage and geotechnical characterizationof Mount Etna ash. The results give interesting information for a rational reuse of this ash in GeotechnicalEngineering preserving the human health
Site-dependent response spectra at the town of Sellano for the 1997-1998 Umbria –Marche seismic sequence
No full textIn the period between 3rd September and 14th October 1997, seven main seismic events occurred in the regions of Umbria and Marche in Italy. The events have been recorded by more than 30 stations of the Servizio Sismico Nazionale (S.S.N. 1999) located in this area.
Because of the earthquakes, that struck the Umbro-Marchigiano area of Italy from September 1997 to April 1998, a lot of small, old centres suffered great damage to their buildings, including the towns of Fabriano, Nocera Umbra and Sellano. The main shocks that affected Sellano took place on 26 September 1997 and on 14 October 1997. On 26 September at 00:33 the epicentral area was located in the town of Colfiorito, about 10 km to the north of Sellano. The shock of 14 October was located only 3 km away from Sellano.
The seismic sequence, which occurred in the Umbria and Marche Regions in 1997-1998, even if it was characterised by quite moderate magnitudes, caused significant damage to buildings and determined the failure of many slopes. An explanation of this phenomenon can certainly be looked for in the geotechnical characteristics of the soil involved; even if the high vulnerability of many masonry buildings and the cumulative effect due to the long earthquake repetition also play an important role.
On the basis of the site characterisation of the Sellano area, the soil response was analysed, and a grade-2 microzonation was performed by Massimino et al. 2001. Furthermore a grade-3 microzonation was performed by Capilleri et al. 2001 including microzonation maps in terms of acceleration and amplification ratio.
The aim of this work is to compare acceleration spectra obtained on the basis of the acceleration records (S.S.N.1999) with those provided for the last of EC8, (2002) which considers seven subsoil classes instead of three classe
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