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The paper presents a mechanical-based framework for the evaluation of local-scale seismic fragility curves. The approach is oriented to a seismic vulnerability assessment of unreinforced masonry buildings and makes use of basic exposure data easily obtained from survey or available in existing database. An efficient finite element model and static nonlinear analyses are employed to assess the structural behaviour. The mechanical-based fragility curves are evaluated using Monte Carlo simulations that allow to account for the uncertainties propagation. The proposed approach is tested on a case-study regarding the city centre of Cosenza, in southern Italy, using exposure information available from CARTIS database. [ABSTRACT FROM AUTHOR]

• Light metal exoskeletons are used for integrated seismic-energy retrofit of existing RC buildings. • Three different solutions are applied to increase the seismic performances of an existing RC school buildings. • Seismic behaviour before and after interventions is investigated in the static non-linear field. • The comparisons among intervention techniques are made in terms of the seismic safety index provided by the Italian technical standard. • Local reinforcement interventions on RC school building columns are performed together with the applied exoskeletons to attain the minimum safety index required by the standard code for this building category. Italian built heritage is highly vulnerable due to old public and private buildings designed without recent seismic and energy regulations. In particular, school buildings represent a critical typology that should be retrofitted to guarantee safety and comfort to the users. In this framework, interventions from building outside able to avoid interruption of school activities should be required. A solution to solve this issue can be found in the retrofit solution with exoskeletons. In this scenario, the paper presents the comparison among three similar solutions of metal lightweight exoskeletons for the integrated seismic-energy retrofit of a RC school building assumed as a case study. The RC structure of the school is firstly modelled with a finite element software and then subjected to pushover analysis before and after retrofit interventions to assess the benefit of each exoskeleton solution. The comparisons among intervention techniques are made in terms of the seismic safety index (ζ E) provided by the Italian technical standard. The results show the more or less efficacy of the different inspected systems, even if integrative local interventions are needed to reach the minimum safety index (0.60) required for school buildings. As a conclusion, these novel light metal exoskeletons have proven to be efficient retrofitting systems for residential buildings or even for school buildings with regular façades and plan layouts. [ABSTRACT FROM AUTHOR]

• The seismic risk assessment of typical historical masonry churches located in the Banat region, Romania, through multilevel analysis procedures is presented. • By selecting six churches in this area, territorial scale assessments are carried out by means of LV0 and LV1 methods recommended by Italian code. • In a second step, local (LV2) and global (LV3) numerical analyses are performed on one representative church with the aim of identifying possible collapse mechanisms. • The LV2 method is applied by following a computational kinematic limit analysis approach. • In the LV3 method, modal linear and non-linear static analyses are carried out on a global finite element model. This paper aims to show some results of seismic assessment of Romanian Orthodox existing masonry churches, by extending the multi-level approach proposed by the Italian directive for seismic risk evaluation of cultural heritage. To this scope, a sample of six existing churches is examined, belonging to a church typology characterized by a single vaulted nave and a bell tower incorporated into the main façade. All churches considered in this study are located in the Banat region, which is an area with a medium–high seismic hazard. Firstly, territorial Level of Valuations (LV0 and LV1) are conducted on the churches sample examined. Afterwards, local (LV2) and global (LV3) valuations are performed on a case study, the Învierea Domnului church, assumed representative of all the churches sample under consideration. In particular, local analyses are performed on some church architectural portions with the kinematic limit analysis. Whereas, global analyses are conducted with non-linear push-over approach. Comments and comparisons of the obtained results are reported for each LV examined. [ABSTRACT FROM AUTHOR]

This paper investigates the seismic performance and vulnerability of multi-span Reinforced Concrete (RC) bridges with unequal height piers exposed to varied corrosion damage scenarios. An advanced three-dimensional nonlinear finite element modelling technique is developed and verified with available experimental results of a reference shake table test on a large-scale RC bridge. In addition to the pristine state of the reference bridge, various hypothetical corrosion scenarios, including the symmetrical and asymmetrical corrosion of piers, are considered. Several nonlinear analyses, including the pushover and Incremental Dynamic Analysis (IDA) approach, are performed to evaluate the seismic behaviour and vulnerability of hypothetical RC bridge specimens. The influence of symmetrical and asymmetrical corrosion of piers on nonlinear dynamic behaviour and failure mechanism (both in the global and local scales) of studied bridges are then discussed. Finally, the IDA results are used to develop time-dependent fragility curves. The analyses show that seismic vulnerability of a deteriorated irregular multi-span RC bridge crucially depends on the corrosion scenario of its piers, where the unbalanced distribution of seismic ductility demand might be regulated/intensified by different corrosion scenarios. Moreover, some corrosion scenarios resulted in near-synchronised failure of unequal height piers. • Modelling guidelines for advanced 3D finite element modelling of irregular RC bridges, including corrosion damage models. • Impact of various corrosion scenarios on capacity and seismic failure sequences of irregular ageing multi-span RC bridges. • Time-dependent seismic fragility analysis of corrosion-damaged multi-span RC bridges with substructural irregularity. • Influence of corrosion scenario on unbalanced distribution of ductility demands in irregular multi-span RC bridges. [ABSTRACT FROM AUTHOR]

• The corrosion effects due to the carbonation phenomenon are evaluated considering existing RC bridges. • Multi-modal pushover analysis was conducted in order to evaluate the influence of the corrosion effects on the seismic performance of existing RC bridges considering two different collapse mechanisms: the ductile collapse mechanism and the brittle collapse mechanism. • The results are summarized in terms of appropriate risk indices to highlight the evolution of the collapse mechanisms during the life of the structure. Recent collapse events of existing reinforced concrete bridges have increased the attention on the mandatory and suitable maintenance of these strategic constructions. In fact, most of these failures were due to an inadequate scheduling of maintenance interventions. One of the main issues concerning the load-bearing capacity of existing reinforced concrete structures is related to the steel reinforcement corrosion caused by carbonation phenomenon. Such aspect should not be even more overlooked considering the strategic role of infrastructures like the bridges of the Italian motorway network, mainly built around the 1960′s and widely used even right now. Consequently, reinforced concrete bridges require the execution of maintenance interventions in order to guarantee an adequate safety level under both serviceability conditions and exceptional loads, also considering that they were often designed without taking into account seismic actions. This paper investigates the seismic performance of five existing reinforced concrete bridges under several corrosion scenarios of piers steel reinforcement caused by carbonation phenomenon. In particular, three different corrosion levels (slight, moderate and high) are considered by analysing the evolution of the phenomenon effects for a structure lifetime equal to 75 years. The seismic vulnerability is evaluated by defining appropriate risk indices expressed in terms of peak ground acceleration and corresponding return period. The risk indices are determined by performing modal pushover analyses on finite element models of the bridges, considering the corrosion effects in terms of steel rebars cross section reduction. Some correlations between corrosion levels and risk indices are drawn. [ABSTRACT FROM AUTHOR]

• Novel method for simplified 2D shell modelling of one-way jack arch floors. • 2D elastic orthotropic shell properties are calibrated via an iterative procedure. • Calibration based on comparisons with detailed nonlinear 3D floor modelling. • Application to timber/steel and tile vault floors of Eixample district, Barcelona. • Seismic performance analysis of an Eixample building with two different floors. The type of floor system has a decisive role in the seismic performance of unreinforced masonry buildings. The in-plane stiffness of the floors has to be adequately represented in the numerical modelling of existing buildings, as it can influence their seismic capacity. This paper investigates the seismic behaviour of one-way arch floor systems composed of steel or timber beams, and ceramic tile vaults. The main objective of the research is to provide a numerical procedure for the simplified modelling of jack arch floor systems in the seismic assessment of unreinforced masonry buildings. The presented approach aims to provide values for the orthotropic properties of simplified floor models composed of elastic 2D shell elements. The orthotropic elastic properties are computed and calibrated by means of comparisons with detailed 3D nonlinear models of the floors. The case study is a multi-storey existing masonry building of the historical "Eixample" district in Barcelona, which includes one-way arch floor systems. The Finite Element Method has been used for the numerical simulation of the seismic performance through nonlinear static (pushover) analyses. The results of the study contribute to a better understanding of the effect of the behaviour of one-way floors with steel or timber beams and tile vaults on the seismic response of masonry buildings. This work provides indicative values for the proper modelling of these particular floor slabs. The proposed methodology is also applicable to the numerical simulation of any other one-way floor system. [ABSTRACT FROM AUTHOR]