NODE: a large‐scale seismic risk prioritization tool for Italy based on nominal structural performance

Abstract

Prioritization of seismic risk mitigation at a large scale requires rough-input methodologies able to provide an expedited, yet conventional, assessment of the seismic risk corresponding to the portfolio of interest. In fact, an evaluation of seismic vulnerability at regional level by means of mechanics-based methods is generally only feasible for a fraction of the portfolio, selected according to prioritization criteria, due to the sheer volume of information and computational effort required. Therefore, conventional assessment of seismic risk via simple indices has been proposed in literature and in some guidelines, mainly based on the comparison of code requirements at the time of design and current seismic demand. These indices represent an attempt to define a relative seismic risk measure for a rapid ranking to identify the part of the portfolio that deserves further investigation. Although these risk metrics are based on strong assumptions, they have the advantage of only requiring easy-to-retrieve data, such as design year and location as the bare minimum, making them suitable for applications within the risk analysis industry. Moreover, they can take both hazard and vulnerability into account, albeit conventionally, and can be manipulated in order to account for exposure in terms of individual or societal risks. In the present study, the main assumptions, limitations, and possible evolutions of existing prioritization approaches to nominal risk are reviewed, with specific reference to the Italian case. Furthermore, this article presents the software NODE (available to interested readers), which enables the computation of location-specific code-based seismic performance demands, according to the Italian code and the evolution of seismic classification since 1909. Finally, this study intends to contribute to the ongoing debate on strategies for large-scale seismic assessment for building stock management purposes.

Planning for More Resilient and Safer Cities: A New Methodology for Seismic Risk Assessment at the Urban Scale, Applied to a Case Study in Italy

“…Indeed, through a series of principles and rules established in building codes, the resulting construction ought to implicitly satisfy some structural reliability requirements that should ensure its resistance to seismic forces. As discussed in [52], seismic regulatory codes in Italy have undergone a significant number of changes in the last century. At the national level, the most update norm in terms of standards for construction is the Technical Standards for Construction 2018 [53], with its ministerial circular, which prescribes a minimum safety level against seismic force, both for new buildings and retrofitting interventions on existing constructions.…”

Nonlinear 3D Finite Element Analysis of a Coupled Soil–Structure System by a Deterministic Approach

“…Moreover, W was reduced to 40% for buildings in Category I. W was defined, according to the RDL no. 573 of 04/29/1915, as the sum of dead loads plus the quasi-permanent live loads, increased by 50%, to take into account the vertical seismic action [20].…”

Japanese attitudes toward risk control in seismic design in light of observation, prediction, and actual performance of building structures

“…Around that time two municipalities in California (Los Angeles and San Francisco) also enacted building codes which related the seismic coefficient with building height or period, and in the 1959 Structural Engineers Association of California (SEAOC) model code, 17 design seismic loads were determined by considering the natural period and the effects of the energy dissipation capacity of the building. The Italian seismic code enacted in 1975 also reflected these structural characteristics, as well as seismic zone and soil type, into the design seismic load prescription 18 …”

“…The Italian seismic code enacted in 1975 also reflected these structural characteristics, as well as seismic zone and soil type, into the design seismic load prescription. 18 In 1981, a major overhaul of the BSL took place in Japan as a consequence of the 1968 Tokachi-Oki and the 1978 Miyagi-Oki earthquakes, which had caused severe damage in buildings complying with the regulations then in force. The main feature of the 1981 BSL, which is still in practice now, was the introduction of a two-level seismic design, leading to the mandatory safety verifications not only for moderate events (Level 1) but also for a maximum expected event (Level 2).…”