Nakon EC8: novi talijanski propisi za protupotresnu gradnju

The 2002 Molise earthquake, which was defined by seismologists as a normal event in the geodynamics of the Italian peninsula but had an international resonance due to the collapse of a primary school, triggered a series of research initiatives in earthquake engineering and significant modifications to building codes in Italy. The modifications were completed at the beginning of 2008 with the release of a new comprehensive building code for Italy. This document was mainly inspired by Eurocode, but it contains some changes and improvements. In this paper, comments are made on three specific parts of the new code: definition of seismic action, analysis of liquefaction and analysis of slope stability. For the first part, seismic action is defined based on a recent careful study of the seismic hazard in Italy. For liquefaction analysis, some developments are given, keeping the same structure used in Eurocode. Finally, for slope stability, improvements are introduced to avoid overestimation of pseudostatic forces in conventional analyses.Iako su potres u pokrajini Molize, koji se dogodio 2002. godine, seizmolozi kategorizirali kao uobičajenu geodinamičku pojavu na talijanskom poluotoku, on je imao veliki odjek u javnosti jer je prouzročio rušenje jedne osnovne škole. Taj je događaj u Italiji inicirao mnoga istraživanja u području potresnog inženjerstva i značajne izmjene zakona o gradnji. Te su izmjene dovršene početkom 2008. godine, kada je obznanjen novi, detaljno razrađen, talijanski zakon o protupotresnoj gradnji. Taj je zakon izrađen po uzoru na Eurokod, ali donosi i neke novine i unaprje|enja. Iz tog se zakona u ovom članku komentiraju: definicija seizmičkog opterećenja, te analize potencijala likvefakcije i stabilnosti kosina. Seizmičko je opterećenje određeno na temelju nedavnih detaljnih studija seizmičkog hazarda na području Italije. Što se tiče likvefakcije, prikazane su neke novine u odnosu na Eurokod. Konačno, u vezi stabilnosti kosina unesene su izmjene u odnosu na Eurokod da se izbjegnu prevelike pseudostatičke sile u konvencionalnim analizama stabilnosti

Recognition of the Mechanical Properties for Soils in Complex Conditions: A Case Study

AbstractThe aim of this paper is to discuss the shear resistance angle φ’ of structurally complex formations in San Giuliano del Sannio (CB) for the construction of a strategic building. Large lithoid stones in a clayey-like matrix constitute the main soil formations. In this condition, it is doubtful how to evaluate φ’ for geotechnical design, being very small the values obtained by conventional laboratory tests on the fine-graded matrix. Two alternative approaches could be suggested to detect the geotechnical parameters for design, specifically the φ’ the angle: using the shear waves velocity and its empirical relationship with the soil resistance and through the back-analyses of an existing embedded retaining wall. It is shown that the two proposed pattern give more realistic values of the soil resistance for this kind of material, with respect to the ones obtained by conventional laboratory tests

A Step Into the Definition of the Seismic Risk for the City of Benevento (Italy)

This paper gives a contribution in the definition of the seismic hazard for the city of Benevento in Southern Italy, from a geotechnical engineering viewpoint. To pursue this goal, an extensive geotechnical characterization of the city subsoil was achieved collecting data available at the Department of Geotechnical Engineering, University of Napoli and Benevento municipal technical office. Attention was paid in defining strain dependent shear stiffness and damping ratio for the geomaterials present in the urban area. A new method to correct the Masing criteria was adopted. Numerical analyses were performed considering the subsoil as a continuous one-phase equivalent linear medium. The 1-D analyses were carried out using Shake-like codes. The seismic hazard in the city was evaluated on the basis of two seismic scenarios, respectively characterized by low and high acceleration levels. The final result of the work is a seismic zonation of the city of Benevento. It was found that zonation maps are largely dependent from the chosen seismic scenario

A Step Into the Definition of the Seismic Risk for the City of Benevento (Italy)

This paper gives a contribution in the definition of the seismic hazard for the city of Benevento in Southern Italy, from a geotechnical engineering viewpoint. To pursue this goal, an extensive geotechnical characterization of the city subsoil was achieved collecting data available at the Department of Geotechnical Engineering, University of Napoli and Benevento municipal technical office. Attention was paid in defining strain dependent shear stiffness and damping ratio for the geomaterials present in the urban area. A new method to correct the Masing criteria was adopted. Numerical analyses were performed considering the subsoil as a continuous one-phase equivalent linear medium. The 1-D analyses were carried out using Shake-like codes. The seismic hazard in the city was evaluated on the basis of two seismic scenarios, respectively characterized by low and high acceleration levels. The final result of the work is a seismic zonation of the city of Benevento. It was found that zonation maps are largely dependent from the chosen seismic scenario

Earthquake Geotechnical Engineering Aspects of the 2012 Emilia-Romagna Earthquake (Italy)

On May 20, 2012 an earthquake of magnitude ML=5.9 struck the Emilia Romagna Region of Italy and a little portion of Lombardia Region. Successive earthquakes occurred on May 29, 2012 with ML=5.8 and ML=5.3. The earthquakes caused 27 deaths, of which 13 on industrial buildings. The damage was considerable. 12,000 buildings were severely damaged; big damages occurred also to monuments and cultural heritage of Italy, causing the collapse of 147 campaniles. The damage is estimated in about 5-6 billions of euro. To the damage caused to people and buildings, must be summed the indirect damage due to loss of industrial production and to the impossibility to operate for several months. The indirect damage could be bigger than the direct damage caused by the earthquake. The resilience of the damaged cities to the damage to the industrial buildings and the lifelines was good enough, because some industries built a smart campus to start again to operate in less of one month and structural and geotechnical guidelines were edited to start with the recovering the damage industrial buildings. In the paper a damage survey is presented and linked with the ground effects. Among these, soil amplification and liquefaction phenomena are analyzed, basing on the soil properties evaluation by field and laboratory tests. Particular emphasis is devoted to the damaged suffered by the industrial buildings and to the aspects of the remedial work linked with the shallow foundation inadequacy and to the liquefaction mitigation effects

Engineering Reconnaissance Following the October 2016 Central Italy Earthquakes - Version 2

Between August and November 2016, three major earthquake events occurred in Central Italy. The first event, with M6.1, took place on 24 August 2016, the second (M5.9) on 26 October, and the third (M6.5) on 30 October 2016. Each event was followed by numerous aftershocks. As shown in Figure 1.1, this earthquake sequence occurred in a gap between two earlier damaging events, the 1997 M6.1 Umbria-Marche earthquake to the north-west and the 2009 M6.1 L’Aquila earthquake to the south-east. This gap had been previously recognized as a zone of elevated risk (GdL INGV sul terremoto di Amatrice, 2016). These events occurred along the spine of the Apennine Mountain range on normal faults and had rake angles ranging from -80 to -100 deg, which corresponds to normal faulting. Each of these events produced substantial damage to local towns and villages. The 24 August event caused massive damages to the following villages: Arquata del Tronto, Accumoli, Amatrice, and Pescara del Tronto. In total, there were 299 fatalities (www.ilgiornale.it), generally from collapses of unreinforced masonry dwellings. The October events caused significant new damage in the villages of Visso, Ussita, and Norcia, although they did not produce fatalities, since the area had largely been evacuated. The NSF-funded Geotechnical Extreme Events Reconnaissance (GEER) association, with co-funding from the B. John Garrick Institute for the Risk Sciences at UCLA and the NSF I/UCRC Center for Unmanned Aircraft Systems (C-UAS) at BYU, mobilized a US-based team to the area in two main phases: (1) following the 24 August event, from early September to early October 2016, and (2) following the October events, between the end of November and the beginning of December 2016. The US team worked in close collaboration with Italian researchers organized under the auspices of the Italian Geotechnical Society, the Italian Center for Seismic Microzonation and its Applications, the Consortium ReLUIS, Centre of Competence of Department of Civil Protection and the DIsaster RECovery Team of Politecnico di Torino. The objective of the Italy-US GEER team was to collect and document perishable data that is essential to advance knowledge of earthquake effects, which ultimately leads to improved procedures for characterization and mitigation of seismic risk. The Italy-US GEER team was multi-disciplinary, with expertise in geology, seismology, geomatics, geotechnical engineering, and structural engineering. The composition of the team was largely the same for the two mobilizations, particularly on the Italian side. Our approach was to combine traditional reconnaissance activities of on-ground recording and mapping of field conditions, with advanced imaging and damage detection routines enabled by state-of-the-art geomatics technology. GEER coordinated its reconnaissance activities with those of the Earthquake Engineering Research Institute (EERI), although the EERI mobilization to the October events was delayed and remains pending as of this writing (April 2017). For the August event reconnaissance, EERI focused on emergency response and recovery, in combination with documenting the effectiveness of public policies related to seismic retrofit. As such, GEER had responsibility for documenting structural damage patterns in addition to geotechnical effects. This report is focused on the reconnaissance activities performed following the October 2016 events. More information about the GEER reconnaissance activities and main findings following the 24 August 2016 event, can be found in GEER (2016). The objective of this document is to provide a summary of our findings, with an emphasis of documentation of data. In general, we do not seek to interpret data, but rather to present it as thoroughly as practical. Moreover, we minimize the presentation of background information already given in GEER (2016), so that the focus is on the effects of the October events. As such, this report and GEER (2016) are inseparable companion documents. Similar to reconnaissance activities following the 24 August 2016 event, the GEER team investigated earthquake effects on slopes, villages, and major infrastructure. Figure 1.2 shows the most strongly affected region and locations described subsequently pertaining to: 1. Surface fault rupture; 2. Recorded ground motions; 3. Landslides and rockfalls; 4. Mud volcanoes; 5. Investigated bridge structures; 6. Villages and hamlets for which mapping of building performance was performed

Reconnaissance of 2016 Central Italy Earthquake Sequence

The Central Italy earthquake sequence nominally began on 24 August 2016 with a M6.1 event on a normal fault that produced devastating effects in the town of Amatrice and several nearby villages and hamlets. A major international response was undertaken to record the effects of this disaster, including surface faulting, ground motions, landslides, and damage patterns to structures. This work targeted the development of high-value case histories useful to future research. Subsequent events in October 2016 exacerbated the damage in previously affected areas and caused damage to new areas in the north, particularly the relatively large town of Norcia. Additional reconnaissance after a M6.5 event on 30 October 2016 documented and mapped several large landslide features and increased damage states for structures in villages and hamlets throughout the region. This paper provides an overview of the reconnaissance activities undertaken to document and map these and other effects, and highlights valuable lessons learned regarding faulting and ground motions, engineering effects, and emergency response to this disaster