This paper is addressed to construction professionals, engineers and architects entrusted to assess the seismic vulnerability level of historical and architectural heritage buildings and to ensure their safety. Masonry building collapses caused by seismic events highlight frequent cases of loss of equilibrium, that is, the rigid overturning of structural portions. The study of collapse mechanisms can be effectively performed using the kinematic analysis methods, recently adopted by the Italian Building Code. Referring to a particular structural element (the masonry arch), a typical component of historic buildings, this paper proposes an original approach to perform seismic verification based on an algorithm devoted to this topic. Thanks to this algorithm, the a-priori choice of failure interfaces is avoided, as it is possible to individualize the kinematism and its related collapse load factor. The seismic verification which follows is performed according to the Italian Building Code.
seismic vulnerability
VULNERABILITY ANALYSIS OF RELEVANT AND STRATEGIC BUILDINGS IN SEISMIC ZONE 3 MUNICIPALITIES OF LOMBARDY REGION
The vulnerability analysis is a quick solution for the identification of buildings that, because of the materials characteristics or construction quality or structural scheme, are in critical conditions with respect to their seismic vulnerability, such that either damage or collapse may occur in case of earthquake. The analysis results, carried out on concrete and masonry buildings through the filing of I and II level records /1/ /2/, are based on weighted sums of 11 (12 for concrete) parameters to which the data collectors assign a quality class, taking into account the observed situations during an inspection, the similarities with comparable buildings (with relation to the construction period and the used technology) and the geometrical features, such as the average floor area and the resistant areas. In case of vulnerable buildings, more detailed analysis will be further necessary to define the collapse mechanism and to assess, in case, the necessary rehabilitation works
SEISMIC VULNERABILITY OF THE EMBANKMENTS OF RESERVOIR BASINS FOR FLOOD REDUCTION LOCATED ON THE TRIBUTARY STREAMS OF THE PO RIVER (ITALY)
This paper presents methodology and results of seismic vulnerability analyses performed in flood expansion areas of Parma River, tributary streams of the Po River in Emilia-Romagna (Italy). The proposed methodology included the following steps: collection of the pre-existing information and geologic map; performing of in-situ investigations and geotechnical laboratory tests on the collected soil samples; definition of the geologic-geophysical and geotechnical models; individuation of the expected seismic inputs; analyses of Local Seismic Response; identification of a number of significant sections; analyses of slope stability. The results obtained are discussed in the paper in order to illustrate how the methodology employed enables definition of the seismic vulnerability of the flood expansion area and allows to give indications regarding its future use. The proposed study points out that the flood expansion area has a level of safety adequate for guaranteeing seismic stability taking into account the rules of Italian Ministerial Decrees 14.01.2008 and 24.03.1982. It is therefore possible to consider the area suitable also as a reservoir basin and no intervention is required other than normal monitoring and maintenance.
SEISMIC VULNERABILITY ASSESSMENT: FROM INDIVIDUAL BUILDINGS TO THE URBAN FABRIC AND BEYOND. APPLICATIONS TO THE SALÒ CASE (BRESCIA PROVINCE, ITALY)
In the last years the “disaster” scientific community has increasingly recognized the relevance of vulnerability and related concepts (resilience, coping capacity, adaptation) in managing natural risks. The limitation of structural measures taken with the aim of reducing the hazard severity and/or frequency has come to evidence. Those are still important; yet other measures able to reduce exposure and vulnerability are recognized as increasingly necessary. Seismic engineers have been dealing with physical vulnerability of structures since long time, as clearly nothing can be really done to mitigate earthquakes as phenomena. Not only new constructions were covered by analysis and care, but also the large built stock, including historic heritage.
Seismic engineers have achieved significant advancement in vulnerability assessment. However, several recent events in Italy and elsewhere have dramatically shown that structural resistance is one component of the overall seismic response of complex systems like cities, but not the only one. Urban and spatial planning decisions should embed concerns regarding amplification zones, potential induced effects triggered by an earthquake (like tsunami or land- slides), cascading effects among interconnected systems. This has been done only to a very limited extent until now. Among the reasons is the lack of tools for actually addressing the multiple vulnerability facets that must be looked at for such a comprehensive mitigation effort. In the article, the results of a recently concluded European funded research project (Ensure) are presented; an application of the tool and methodology developed during the project has been carried out on the case of the Salò municipality in the province of Brescia, Northern Italy.
ASSESSMENT OF THE MOST DAMAGED HISTORIC CENTRES OF THE REGION EMILIA ROMAGNA DUE TO THE EARTHQUAKE OF THE 20th AND 29th OF MAY 2012
The Emilia Romagna earthquake of the 20th of May 2012 has damaged some of the historic centres closer to the epicentre of this event. Aftershocks and a second earthquake on the 29th of May 2012 registered in the same region have caused around 30 dead people, 350 of injured people and several damage types to historic assets. In this paper the typical features of the residential constructions in the areas damaged by these earthquakes are introduced and the seismic vulnerability of the Comune of Cento is carried out by using the FaMIVE approach. The same area has also been surveyed by the Italian Civil Protection to assess the safety of the buildings with the aid of AeDES form. The damage scenario observed on site, the safety judgements conducted by AeDES and the forecasted vulnerability obtained by FaMIVE will be illustrated for some building clusters selected in the Comune of Centro.
SEISMIC UPGRADE OF A R.C. BUILDING WITH DISSIPATIVE BRACES
The paper illustrates the design and execution of seismic retrofit of a building with reinforced concrete structure, through the use of metal braces with integrated viscous damper. The work is part of a larger project that also included works by expanding the classroom through the use of stilts, closed with drywall that do not interfere in the structural behavior of the building. The economy and the possibility of working without closing the buibing, are its salient features. The cost of structural works was in fact of 190,000 € plus VAT and charges, amounting to less than 170€/sqm. A sum much less than the cost of traditional interventions (400€/sqm).
This paper is available in Italian only.
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Damage analysis of the town of Onna (L’Aquila) after the April, 6, 2009 earthquake
The paper addresses the analysis of the seismic damage of Onna, a village near L’Aquila almost completely destructed during the 6 April event. A purposely developed data form has been used to collect the ob- servations of several surveyors. The analysis of the construction typologies, of the seismic vulnerability and of the damage lead to the conclusion that the poor characteristics of the masonry played a dramatic role in the seismic damage suffered by the buildings, despite that some typical historical seismic provisions were present (limited height of the buildings, wood ties). The low level of damage of some unreinforced masonry buildings in Onna, built following a good construction practice, indirectly confirms the heavy role played by the seismic vulnerability in the damage observed.
For this paper is available an extended abstract after the text in Italian.
Il ruolo della fascia di piano nel comportamento sismico degli edifici in muratura
This paper deals with the role of the spandlers in the seismic behaviour of the masonry building. Particularly the seismic performance of masonry walls in their own plane have been analyzed by mean of non-linear static analyses performed on schemes of equivalent frames. Different geometrical and structural configurations of the spandlers have been considered and the corresponding capacities in coupling the piers have been deepen too. Both beams and columns have been modeled considering lumped plasticity at the ends of the elements. The results obtained confirmed the very strategic role of the spandlers in the seismic capacity of the masonry building
This paper is available in Italian only