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Within the 2019–2021 research agreement between the Civil Protection Department (DPC) and the Network of University Laboratories for Earthquake Engineering (ReLUIS), the work package WP4 "Seismic Risk Maps—MARS" is specifically devoted to update the 2018 release of the Italian National Seismic Risk Assessment. To this end, the previously considered models of hazard, exposure and vulnerability will be critically reviewed and updated by taking advantage also from the results deriving from other WPs of the DPC-ReLUIS research project. In the present paper some of the most relevant aspects that are being introduced in the development of the new Italian risk maps have been described and shortly analysed. First, a significant upgrade of the vulnerability model implemented in the new version of the platform used for risk calculation (IRMA) is proposed, where reference to the six EMS-98 classes is made also considering regional vulnerability features. Further, empirical data from observed real damage are integrated with results from numerical simulations (mechanical approach), in particular for reinforced concrete buildings. Finally, some special construction types such as schools, churches and bridges are included in order to provide a more comprehensive view of the national risk. [ABSTRACT FROM AUTHOR]

This study investigates the seismic response of reinforced concrete buildings designed according to the current Italian building code. Number of stories, site hazard, presence and distribution of masonry infill panels, and type of lateral resisting system are the key investigated parameters. The main issues related to design and modeling are discussed. Two Limit States are considered, namely Global Collapse and Usability-Preventing Damage. The main aim of the study is a comparison between the seismic response of the buildings, investigated through nonlinear static and dynamic analyses. Irregularity in the distribution of infill panels and site hazard emerge as the most influential parameters. [ABSTRACT FROM AUTHOR]

This paper offers a parametric study on reinforced concrete frames representative of structural types widely present in the European building stock. It focuses on buildings which have been designed only for vertical loads. These are detailed by adopting the simulated design procedure proposed in Masi (Bull Earthq Eng 1(3):371-395, 2003) and introduced in the European code for the seismic assessment and retrofitting of existing buildings EC8-3 (CEN in Eurocode 8: design of structures for earthquake resistance-part 3: assessment and retrofitting of buildings, prEN 1998-3, Brussels, 2005). Some structural types have been selected by varying the numbers of storeys (2, 4 and 8 storeys) and the infill configuration (bare, infilled and pilotis frames). The seismic analyses have been carried out applying linear and non-linear static analysis methods in accordance to EC8-3. Different performances were computed by adopting different seismic intensities (4 cases: very low to high seismic zone), behaviour factors (4 cases, only for linear analysis), knowledge levels (3 cases), and concrete strength values (3 cases: 10, 18 and 28 MPa). The performances were compared to investigate the consistency of the analysis methods under study that is to verify whether they provided results which were mutually consistent in terms of outcomes regarding safety verifications taking into account differences in complexity and accuracy. The role of some structural parameters is emphasized and future developments of the study aimed at upgrading the current version of the European code are outlined. [ABSTRACT FROM AUTHOR]

A damaging seismic sequence hit a wide area mainly located in the Emilia-Romagna region (Northern Italy) during 2012 with several events of local magnitude $$\hbox {M}_\mathrm{l} \ge 5$$ , among which the $$\hbox {M}_\mathrm{l}$$ 5.9 May 20 and the $$\hbox {M}_\mathrm{l}$$ 5.8 May 29 were the main events. Thanks to the presence of a permanent accelerometric station very close to the epicentre and to the temporary installations performed in the aftermath of the first shock, a large number of strong motion recordings are available, on the basis of which, we compared the recorded signals with the values provided by the current Italian seismic regulations, and we observed several differences with respect to horizontal components when the simplified approach for site conditions (based on Vs30 classes) is used. On the contrary, when using the more accurate approach based on the local seismic response, we generally obtain a much better agreement, at least in the frequency range corresponding to a quarter wavelength comparable with the depth of the available subsoil data. Some unresolved questions still remain, such as the low frequency behaviour ( $$<$$ 1 Hz) that could be due either to complex propagation at depth larger than the one presently investigated or to near source effects, and the behaviour of vertical spectra whose recorded/code difference is too large to be explained with the information currently available. [ABSTRACT FROM AUTHOR]

In reinforced concrete (RC) structures, the compressive strength of concrete can play a crucial role in seismic performance and is usually difficult to estimate. Major seismic codes prescribe that concrete strength must be determined essentially from in situ and laboratory tests. Mean values obtained from such tests are the reference design values when assessing existing structures under seismic actions. The variability of concrete strength can also play an important role, generally requiring that various homogeneous domains are identified in a single structure, in each of which a specific mean value should be assumed as representative. This study analyzes the inter- and intra-variability of the concrete strength of existing buildings using a very large database made up of approximately 1600 core tests extracted from RC buildings located in the Basilicata region (Southern Italy). The analysis highlighted that concrete strength variability was dependent on the structures' dimensions as well as on the number of storeys. Moreover, the concrete strength of cores extracted from columns was found to be, on average, lower than that from beams, thus justifying the usual practice to extract cores mainly from columns, which results in a conservative approach as well as a more feasible one. Finally, some case studies were analyzed, specifically focusing on the effects of the within-storey variability. Conservative strength values, to be used especially in the case of vertical members subjected to high axial loads, are suggested. [ABSTRACT FROM AUTHOR]