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Papers by giovanni bongiovanni

Infrastructures

The behavior of a reinforced concrete building, seismically isolated with high damping rubber bea... more The behavior of a reinforced concrete building, seismically isolated with high damping rubber bearing (HDRB) and sliding devices (SD), observed during the most important events of the seismic sequence that struck central Italy from August 2016 to January 2017, is analyzed. Due to the epicenter distances, all the events had light effects at the site, thus the isolation system was not always put into action. A previous very low energy earthquake and the ambient vibration analysis are used for comparison. The study of the isolation system response is first carried out and the variability of the resonance frequencies with the input energy at the site is pointed out. These frequencies are quite close to those of the superstructure considered as fixed base. Small cracks were observed after the sequence in some partition walls of the building. The analysis of the superstructure was performed by means of a finite element model, assuming a non-linear model for the isolators, based on previou...

Geosciences, 2021

The vibration effects on the Torre della Moletta and the ruins of the Circus Maximus in Rome are ... more The vibration effects on the Torre della Moletta and the ruins of the Circus Maximus in Rome are analyzed in the framework of a preservation effort of this archaeological area. Thanks to its exceptional size, the Circus hosts many social events with large audience (pop-music, opera concerts, sport celebrations, etc.) every year, thus taking the structures under high anthropic and environmental stress. Recordings were completed before, during, and after the concert of a famous band, on 7 September 2019. Data were analyzed, both in time and frequency domains. The experimental dynamic recordings were coupled with a surface waves test and single-station ambient vibration recordings, which were useful for the geotechnical characterization of the soil. The results pointed out the differences in amplitudes but also in terms of frequency content of the recorded velocities during the concert with respect to before and after it. The maximum velocities recorded at various locations were almost...

Proceedings of the 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2015

The structural analysis of an about 30 m tall building is presented in this paper. It was constru... more The structural analysis of an about 30 m tall building is presented in this paper. It was constructed in 70s, so its use pointed out the issue of the seismic reliability of existing buildings, especially if considered of strategic importance for civil protection. The structure is composed by two parts, the lower one in reinforced concrete, which contains a theatre room, and an upper in steel. The study allowed defining the seismic vulnerability. A refined finite element model was assembled and updated on the basis of comprehensive experimental analyses on materials and structure and also of experimental modal analysis, highlighting the dynamic effect due to the irregularity of the building and the influence of the adjacent building, the seismic joint is missing. The results pointed out a quite high vulnerability of the building to seismic actions and the inadequacy of the pile foundation to support horizontal seismic loads. A retrofit intervention, based on the insertion of a seismic isolation system and the realization of a seismic joint with the adjacent building, is proposed. It allows reducing the horizontal forces in the piles and the torsional movements of the structure.

Scientific Data, 2019

In August 2016, a magnitude 6.0 earthquake struck Central Italy, starting a devastating seismic s... more In August 2016, a magnitude 6.0 earthquake struck Central Italy, starting a devastating seismic sequence, aggravated by other two events of magnitude 5.9 and 6.5, respectively. After the first mainshock, four Italian institutions installed a dense temporary network of 50 seismic stations in an area of 260 km2. The network was registered in the International Federation of Digital Seismograph Networks with the code 3A and quoted with a Digital Object Identifier (https://doi.org/10.13127/SD/ku7Xm12Yy9). Raw data were converted into the standard binary miniSEED format, and organized in a structured archive. Then, data quality and completeness were checked, and all the relevant information was used for creating the metadata volumes. Finally, the 99 Gb of continuous seismic data and metadata were uploaded into the INGV node of the European Integrated Data Archive repository. Their use was regulated by a Memorandum of Understanding between the institutions. After an embargo period, the dat...

Advances in Civil Engineering, 2018

Curved surface sliders are being used more and more in the seismic isolation of buildings. They a... more Curved surface sliders are being used more and more in the seismic isolation of buildings. They are preferred not only because of their lower cost with respect to elastomeric isolators but also of their technical characteristics, such as the fact that the value of the period of vibration is independent of the mass and the automatic coincidence between the gravity mass center of the superstructure and the stiffness center of the isolation system. In this paper, these features are analysed with reference to simple structures, pointing out the possibility of rotations of the superstructure and the loss of contact in some devices. Finally, the importance of the static friction is also emphasized showing the experimental seismic response of an isolation system under a low-energy earthquake. For all these reasons, the use of nonlinear analysis, revised and detailed in this paper, is advisable for the isolation system made of curved surface sliders.

International Journal of Safety and Security Engineering, 2015

Some recent seismic events pointed out the necessity to revise our way of seismic analysis of str... more Some recent seismic events pointed out the necessity to revise our way of seismic analysis of structures. But what do structural engineers need to design anti-seismic structures? The first step is the analysis of the seismic input, defined by means of the basic hazard analysis and of the local seismic response. Once the description of the seismic hazard is known, the choice of the protection degree should be made on the basis of economical evaluations. Furthermore, the uncertainties about the local seismic response could be very important. The second step is the structural modeling and analysis, whose suitability depends on how good is the description of the material behavior, geometrical characteristics of the structure, and its behavior both in elastic and inelastic ranges. This is accounted for by means of the behavior factor, whose definition and use are quite delicate and often not necessary, especially in lowto medium-seismicity areas, as demonstrated by means of a comprehensive numerical analysis on the construction costs of reinforced concrete buildings. In this article, some important issues are discussed and some proposals are given to improve the technical codes and hence the safety of structures against earthquakes. The seismic input to be used in the retrofit of existing buildings is also discussed.

Earthquake Resistant Engineering Structures IX, 2013

Our knowledge about earthquakes and their effects on structures is still not satisfactory. But wh... more Our knowledge about earthquakes and their effects on structures is still not satisfactory. But what do structural engineers need in order to design antiseismic buildings? As is well known, the first step in any structural design is the analysis of loads and, among these, the seismic input is an important issue. This is defined by means of a basic hazard analysis and the local seismic response. The uncertainties about the local seismic response could be more important than those relating to the basic analysis results. The second step is the structural modeling, where the suitability depends on how good is the description of the material behavior and the structural behavior both in the elastic and inelastic range. Knowledge of these is very important in order to define the behavior factor, which is a measure of the inelastic capacity of the building, i.e., its capacity to dissipate energy. Some recent seismic events in the world have questioned several assumptions of the present design rules, prescribed by the seismic codes. In this paper some issues about the anti-seismic structural design are discussed in order to give some proposals to improve our way of thinking about structural safety against earthquakes.

Annals of Geophysics, 2017

The effects of the traffic-induced vibrations on the external northern wall of the Amphitheatrum ... more The effects of the traffic-induced vibrations on the external northern wall of the Amphitheatrum Flavium are studied with the two objectives of analyzing the amplitudes of such vibrations and extracting the dynamic characteristics of the structure as part of preservation effort. The results obtained in two experimental campaigns, carried out in 1985 and 2014, respectively, are analyzed also as a starting point for future extensive experimental measurements. Data processing consisted in the time domain and frequency domain analyses, in which Fourier transform, power spectral density and cross spectral density were used to extract resonance frequencies, modal shapes and damping. The not always significant values of phase factors and coherence functions pointed out the presence of complex modes and of the nonlinear behavior, which in conjunction with the complex geometry of the structure and its size make the interpretation of the experimental data quite difficult.

Earthquakes cause considerable damages to historical centres, so that a suitable prevention polic... more Earthquakes cause considerable damages to historical centres, so that a suitable prevention policy is necessary to guarantee their conservation. The first step is getting a complete knowledge of the area of interest and of the existing structures. In the selected areas, a detailed analysis to understand the characteristics of the seismic input through the analysis of seismic hazard and microzoning is needed, and so is the seismic performance of buildings by monitoring the seismic response. The paper presents some results of the study carried out on the site of Cerreto di Spoleto and on a complex building of its historical centre

Geophysical surveys and velocimetric measurements in the Cerreto di Spoleto area (Italy), aiming at a seismic microzoning

Bollettino Di Geofisica Teorica Ed Applicata, 2002

Geophysical prospecting and velocimetric measurements, aiming at the seismic microzoning of the C... more Geophysical prospecting and velocimetric measurements, aiming at the seismic microzoning of the Cerreto di Spoleto area (Perugia, Italy), are presented. Starting from the data obtained by previous geological-geomechanical surveys, seismic-refraction investigations were carried out in order to obtain a dynamic characterisation and a geometrical description of both soil and rock materials. The velocimetric measurements were performed through temporary free-field arrays, recording both ambient noise and small-magnitude seismic events. The analysis of the obtained records is still in progress in order to evaluate the local seismic wave amplification.

Retrofit of Existing Buildings with Seismic Isolation: Design Issues and Applications

World Conference on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures Proceedings, 2019

International Journal of Earthquake and Impact Engineering, 2016

The effects of low magnitude vibrations on the base isolated building are analysed and discussed ... more The effects of low magnitude vibrations on the base isolated building are analysed and discussed with reference to two particular structures. The first one is a complex structure, composed by two blocks of three floors, rising up from a common base deck, which is supported by the foundation beams by means of isolation devices. During a moderate intensity earthquake, higher modes were excited, pointing out their very irregular behaviour. In the second case, which regards a building having a hemispherical shape, with three floors plus an underground one, the data recorded under ambient vibrations revealed the significant contribution of the isolation system. In both cases, the experimental behaviour was quite different from the expected one and this should be accounted for when designing base isolation systems.

Vulnerability Analysis and Seismic Retrofit of a Strategic Building

Journal of Performance of Constructed Facilities, 2017

AbstractThe seismic vulnerability analysis of a strategic building is presented in this paper. A ... more AbstractThe seismic vulnerability analysis of a strategic building is presented in this paper. A refined finite-element model was set up on the basis of available experimental results, and updated on the basis of new experimental analyses on materials and structure. As demonstrated by an experimental vibration analysis, the structural behavior is influenced very much by the irregularity of the building and the presence of an adjacent building with no seismic joint. The results indicate a high vulnerability of the building to seismic actions, and the inadequacy of the pile foundation—for which a specific nonlinear analysis was performed—to support horizontal seismic loads. A retrofit intervention, based on the insertion of a seismic isolation system and the realization of a seismic joint with the adjacent building, was proposed, which allows the reduction of horizontal forces in the piles and the torsional movements of the structure.

Behaviour of industrial buildings in the Pianura Padana Emiliana Earthquake

ABSTRACT During the seismic event of May 2012 in the Emilia-Romagna Region (Italy), several indus... more ABSTRACT During the seismic event of May 2012 in the Emilia-Romagna Region (Italy), several industrial structures collapsed or were severely damaged. They had been built following non-seismic old Italian codes, making use of precast concrete structures. In addition, in many cases internal steel shelves exhibited instability. This paper gives a brief description of the collapse observed, based on the construction criteria and the analysis of the seismic event.

The contribution of ENEA to the development of innovative techniques for improving the seismic protection of civil and industrial structures

Since 1988, large efforts have been devoted by the Italian Agency for New Technology, Energy and ... more Since 1988, large efforts have been devoted by the Italian Agency for New Technology, Energy and the Environment (ENEA) to the development, validation and application of innovative anti-seismic (IAS) techniques, namely seismic isolation (SI), passive energy dissipation (ED) and more recently, semi-active control (SAC) of vibrations. New activities are in progress in the framework of both international and national collaborations. With regard to the international collaborations, the ongoing R&D work is being performed within two new projects (SPIDER and SPACE), partially funded by the European Commission, which aim at the development of floor SI systems, SAC systems and systems formed by ED devices and cables. With regard to the national collaborations, the ongoing activities are being performed within new projects partially funded by the National Research Council, the Ministry of University and Scientific and Technological Research, the Italian Working Group on Seismic Isolation (GL...