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The seismic vulnerability assessment of the historic center of Cusco (Peru), an important UNESCO world heritage site, is dealt with in this paper. First, historical development of the city is presented through an in-depth historical analysis of its transformation over time, from the Inca empire to modern days. Then, an extensive in-situ survey activity, that allowed to collect several information about the main structural features concerning ordinary residential buildings, is shown. Based on the collected data, an empirical method calibrated on Italian historic centersfrom the authors is applied. It allowed to obtain Damage Probability Matrices and Fragility Curves for different earthquake intensities, as well as to assess the probability of exceeding certain levels of damage when seismic events of different intensities occur. Based on these predicted damage frequencies, it is possible to prevent irremediable losses and to propose retrofitting interventions which can lead to the seismic vulnerability mitigation for the whole historic center

This paper deals with the seismic response of dual steel frames with and without dissipative metal shear panels. The main goal is to define possible design criteria, for the seismic protection of new and existing buildings, accounting for the main behavioral peculiarities of metal shear panels.To this purpose, based on a large number of historical records that are selected in order to match the main interesting frequencies, Incremental Dynamic Analyses (IDAs) are carried out on two steel frames. These frames have been first designed in order to satisfy specific performances. Then, they have been improved by imposing stricter design goals that have been complied with the application of dissipative metal shear panels.The obtained outcomes highlight that metal shear panels allow to control properly the collapse mechanisms of the frames. Moreover, they can lead to significant increases of collapse accelerations and to a general reduction of both the permanent and the transient story drifts. The paper concludes with the evaluation of the equivalent q-behaviour factor of both the protected and the un-protected frames. As it could be expected, the most effective shear panels are able to produce stronger increase of behavior factors (up to 150%), due to the larger dissipative capacity of the whole structure.

This paper deals with seismic response of dual steel frames with dissipative metal shear panels. The main goal is to provide design indications accounting for the main behavioural aspects of metal shear panels. To this purpose, numerical Incremental Dynamic Analyses (IDAs) using historical records have been carried out on two different steel frames, which have been properly designed in order to comply with specific design criteria. The outcomes highlight that metal shear panels allow a significant increment of collapse peak ground accelerations as well as a general reduction of both permanent and transient story drifts. The paper concludes with the evaluation of the equivalent q-behaviour factors to be used for simplified analysis. As it could be expected, a significant increment (up to 150%) have been determined in case of structures endowed with metal shear panels.

This paper proposes an analytical formulation for designing dissipative metal shear panels for the seismic protection of buildings. In particular, two types of dissipative shear panels are analyzed. The first is based on the adoption of a material characterized by a low yield strength with the application of transversal stiffeners. The latter is a steel shear plate that is properly weakened by perforations. Both the studied typologies are conceived in order to obtain a low shear elastic strength, so that their dissipative function is activated when the other members of the structure are still in the elastic field, even for high intensity earthquakes. Moreover, they are usually designed in order to postpone the trigger of potential buckling phenomena to the field of high shear inelastic demands. The proposed design formulations put in relation demanded shear stresses and strains. In particular, a unique expression, characterized by different coefficients for the two panel typologies, is given. The validity of the proposed expression is corroborated on the basis of the results of several numerical and experimental analysis.

n this paper, the results of a damage reconnaissance activity carried out on eight minor historic centers of Abruzzi after the 6.3 Mw L’Aquila earthquake, occurred on the 6th of April 2009 in the central area of Italy, is presented. In the first part, minor historic centers belonging to the region interested by the earthquake are described. The main morphological features of these centers, to be ascribed to an historical urban development often carried out according to extemporaneous logics, are discussed. Moreover, the main construction typologies are presented: these are made of poor masonry buildings with many fragility sources and are the result of several transformations and stratifications carried out since the medieval age in order to comply with inhabitants needs, but, mostly, not with structural/seismic matters. The second part of the paper is focused on the occurred damage scenarios. The most frequent failure mechanisms of macroelements are shown and the observed damage is classified according to the grades introduced by Grünthal for the definition of the EMS-98 European Macro-seismic scale. Finally, the revealed frequencies of the observed damage grades are organized in damage probability matrices. These are provided as a useful tool able to quantify effectively the occurred damage and to predict the potential losses that have to be expected for similar historical centers in case of future seismic events.

In the current paper, an innovative dissipative shear panel for seismic protection of steel and reinforced concrete buildings is dealt with. It represents an extension of the Buckling Restrained Brace concept in the bi-dimensional space, as it is based on the use of a metal plate, made of aluminum or steel, representing the core of a damper whose hysteretic response could be properly controlled by an external jacket able to inhibit either the most important or, even, all the buckling phenomena under shear forces. The main results of an experimental campaign carried out under cyclic loads on both partially and totally Buckling Inhibited Shear Panels, made of different metallic materials and thicknesses, are analyzed and presented. Two different solutions are analyzed. The former is conceived in order that the buckling inhibition system restrains the out-of-plane displacements of the plate portions centered around the two diagonals, which are more sensible to the firsts and most important critical modes. The latter is based on devices able to restrain the out-of-plane displacements of the whole system. The obtained results allow to observe the significant improvement of dissipative capacity that the buckling inhibition devices are able to provide. Nevertheless, it is pointed out that for reduced thicknesses of the base plate, the system performance could be jeopardized due to the gap between the inhibiting and the inhibited parts within which buckling phenomena could develop.

The extension of damage on churches observed after strong earthquakes evidences the necessity to plan, at regional scale, effective restoration, consolidation and preventive protection strategies. In this framing, the availability of suitable speedy methodologies for the assessment of the main structural fragilities and therefore of the seismic vulnerability of each church is the first fundamental step to be undertaken. This paper presents a methodology for the seismic vulnerability assessment of churches based on a damage reconnaissance activity carried out after the 2009 L’Aquila earthquake on a population of 64 churches. Firstly, the post-earthquake evaluation of damage is described with the aim of identifying both the recurrent damage mechanisms and the main local structural fragilities. As an important outcome, it has been observed that the occurred damage scenario, shown in terms of frequency of pre-established damage levels, can be represented by a binomial distribution, which depends on one parameter only, namely mean damage level. Then, a literature predictive model able to give back the above parameter for several earthquake intensities is applied for outlining fragility curves related to the seismic risk of churches. These curves represent a powerful tool for the prediction of likely future damage scenarios. Finally, some ongoing applications of the proposed analysis methodology to churches of different territorial areas are described.

This article provides the main outcomes obtained downstream from a survey concerning the damage to 64 three-nave masonry churches in Abruzzi resulting from the 2009 LAquila earthquake. First, they are classified according to the typological, structural, and architectural features. Next, the main failure mechanisms observed in the immediate aftermath of the 2009 earthquake are identified and analyzed, taking into account both the global structural response and the local mechanisms involving specific parts of the churches. Damage related to the local mechanisms is classified by means of scores based on both the severity and extension of the revealed cracks. The single scores are combined to define an index measuring the global damage of each church. Such indices are therefore associated with six damage levels, the frequencies of which are organized into damage probability matrices. These matrices can be used in order to quantitatively evaluate the damage scenarios that the studied population of buildings revealed after the seismic event, as well as to predict the damage level that could be expected on similar churches for future earthquakes.

Metal perforated shear plates have been proposed in the last recent years as a suitable solution for passive protection of buildings in seismic-prone zones. The use of soft aluminum alloys seems to be particularly convenient for these special devices. In fact, on the one hand, the low yield strength of the base material allows to control more easily the structural performance without the necessity of large weakening of the base plate. On the other hand, the high ductility that some annealed alloys are able to provide allows significant inelastic deformations, this leading to an appreciable dissipative behavior of the device. In this paper a parametric numerical analysis on pure aluminum perforated shear panels is presented with the aim of examining the panel responses for several arrangements of perforations for different shear deformation demands. In particular, the influence of geometrical parameters related to the hole configuration is investigated.

This paper aims at providing an overview on the current state of the art and on possible future developments concerning the component method implementation for the classification of beam-to-column joints belonging to aluminum moment resisting frames. After a brief discussion on the component method theoretical bases, developed in the past to give a feasible calculation procedure for steel joints, recent experimental and numerical studies, carried out for investigating some aluminum components, are presented and discussed. In particular strengths and weaknesses of the current knowledge are put into evidence, also in light of the peculiarities that make aluminum alloys different from steel. The launch of new research fields, aimed at pursuing an update of the current codes dealing with aluminum structures, is therefore proposed.

La presente memoria riporta i risultati principali di una attività sperimentale e numerica effettuata al fine di indagare la capacità isteretica fornita da sistemi dissipativi basati sull’uso di lastre forate a taglio. Dopo una breve introduzione, in cui i concetti di base che hanno portato a considerare le piastre forate come soluzione conveniente per la protezione sismica delle strutture, sono descritte le prove sperimentali effettuate su due prototipi. Esse hanno messo in evidenza la possibile presenza di criticità del sistema a causa del prematuro sviluppo di fenomeni di instabilità locale che potrebbero influenzare negativamente la risposta dissipativa del sistema. Infine, sono riportati i risultati principali di un'analisi parametrica, basata su modelli numerici agli elementi finiti. Tali risultati sono utilizzati per introdurre formule di progetto utili per la selezione ottimale della geometria di perforazione della lastra da scegliere in funzione della domanda strutturale prevista.

La presente memoria tratta la valutazione della vulnerabilità sismica del centro storico di Scanno (AQ). Lo studio è basato su un modello empirico calibrato sulla base dei danni rilevati su due centri storici abruzzesi colpiti dall'evento sismico del 2009. Tale modello permette di stabilire gli scenari di danno probabili a partire da valutazioni di natura ingegneristica riguardanti le proprietà strutturali degli edifici. Inoltre, la metodologia proposta è concepita per fornire informazioni utili riguardanti le strategie antisismiche più efficaci da mettere in campo al fine di perseguire una attenuazione globale del rischio su scala urbana. I risultati proposti appaiono di particolare interesse, in quanto Scanno presenta tutte quelle peculiarità che caratterizzano i centri storici abruzzesi di origine medievale. Per tale ragione, le curve di fragilità fornite per rappresentare i potenziali scenari di danno potrebbero essere estese ad altre realtà simili, al fine di avere un quadro completo dal quale partire per mettere in campo misure di mitigazione del rischio sismico a scala regionale.

Il presente lavoro mira a sviluppare un’analisi parametrica finalizzata alla definizione di abachi di progetto da utilizzare per la scelta dei giunti trave-colonna di edifici intelaiati di acciaio. La prima parte è dedicata alla validazione della procedura, definita in un’altra memoria, per l’implementazione automatica del metodo delle componenti. Successivamente, tale procedura automatica viene utilizzata per analizzare 11552 casi diversi di giunti bullonati con flangia di e-stremità, ottenuti variando la sezione delle membrature collegate, lo spessore del piatto di estremità, il diametro e la classe dei bulloni. I risultati ottenuti permettono di fornire indicazioni sintetiche sulle scelte progettuali da compiere affinché il giunto selezionato garantisca i requisiti prestazionali minimi in termini di resistenza e rigidezza flessionale.

La memoria fornisce i principali risultati ottenuti attraverso un’accurata ispezione dei danni provocati dal terremoto de L'Aquila (2009) sulle chiese a tre navate appartenenti alle due diocesi abruzzesi di Sulmona-Valva e L’Aquila. È stata esaminata una popolazione di 64 chiese; per ciascuna di esse sono stati messi in evidenza i meccanismi di danno più ricorrenti per i diversi macroelementi, procedendo ad una loro classificazione mediante punteggi crescenti all'aumentare della gravità e dell'estensione delle lesioni rilevate. I punteggi ottenuti per ogni singolo macroelemento sono stati combinati definendo specifico livello di danno Dk rappresentativo dello stato globale post-sismico. L’elaborazione dei valori ottenuti ha permesso di individuare le matrici di probabilità di danno riguardanti sia i singoli macroelementi che le intere chiese. È stato quindi osservato che in entrambi i casi le elaborazioni statistiche sono ben interpretabili mediante distribuzioni probabilistiche binomiali.

This study concerns the behaviour of steel frames protected by different anti-seismic devices (dampers). Typical hysteretic and viscous dampers are arranged in three steel moment-resisting frames (MRFs) having different dynamical features but are designed to accomplish determined performance objectives. The proposed devices are selected following an iterative procedure based on the use of a suitable damage functional, which has been applied to control the behaviour of the protected structures under a specific seismic record. The outcomes obtained by implementing incremental dynamic analyses, carried out on the basis of seven historical records characterized by different features, allow to analyse the improvement of the structural performance due to the considered dampers and, therefore, to provide design information about their employment. The comparison of results is carried out taking into account the dampers capacity to protect the structures from damage, the inter-storey drifts, the residual deformations and the possible amplification effects. In conclusion, the equivalent behaviour factors for each damper type are given, with the aim of providing useful design parameters for the implementation of simplified conventional linear analyses.

The current paper deals with the seismic vulnerability of churches belonging to the south-east pat of the L’Aquila district, an area known as Sulmona-Valva Diocese. The attention is focused on twenty-six three naves churches characterized by similar stylistic, geometric and structural features. In a first stage, a wide survey campaign, conducted in the immediate aftermath of the 2009 seismic event with the aim of classifying the observed damages and to individuate the main recurrent failure mechanisms is presented. Then, a vulnerability assessment is carried out, based on the evaluation of 28 possible local damage mechanisms which are accounted for in order to calculate a global damage index. The empirical observations are interpreted through the statistical distribution of the revealed damages, so to define Damage Probability Matrixes, which represent an effective tool for assessing future seismic likely damage scenarios on the analyzed population of buildings and, therefore, for evaluating seismic risk mitigation strategies to be implemented.

The current paper deals with the seismic vulnerability of churches belonging to the south-east pat of the L’Aquila district, an area known as Sulmona-Valva Diocese. The attention is focused on twenty-six three naves churches characterized by similar stylistic, geometric and structural features. In a first stage, a wide survey campaign, conducted in the immediate aftermath of the 2009 seismic event with the aim of classifying the observed damages and to individuate the main recurrent failure mechanisms is presented. Then, a vulnerability assessment is carried out, based on the evaluation of 28 possible local damage mechanisms which are accounted for in order to calculate a global damage index. The empirical observations are interpreted through the statistical distribution of the revealed damages, so to define Damage Probability Matrixes, which represent an effective tool for assessing future seismic likely damage scenarios on the analyzed population of buildings and, therefore, for evaluating seismic risk mitigation strategies to be implemented.

The behavior of churches during an earthquake is very complex, mainly due to the peculiarities of the buildings, which usually were conceived more for pursuing stylistic aims rather than structural goals. On the other hand, churches are often the result of continuous stratifications generated during their life, which led to constructions characterized by heterogeneous parts working with different modalities. As a consequence, the observation of damages produced by earthquakes could represent a rare occasion for improving the knowledge about the structural behavior of these buildings. In this framing, the current paper deals with the interpretation of the vulnerabilities observed, after the 2009 seismic event, on a church belonging to the district of L'Aquila, the St. Gemma Church in Goriano Sicoli. In a first step a careful analysis of the damage revealed after the 2009 earthquake on similar churches belonging to the same regional area is provided. Then, a suitable FEM numerical model, able to reproduce the revealed damages and properly calibrated by means of Ambient Vibration Tests, is set up for the church under consideration, with the aim of providing a sophisticated tool for weighing up the most important phenomena of failures and to provide some information about the most appropriate retrofitting techniques to be adopted.

Nello studio proposto si analizza il miglioramento delle prestazioni strutturali di telai in acciaio in condizioni sismiche attraverso l’adozione di dispositivi isteretici e viscosi. All’uopo sono esaminati telai di quattro piani e tre campate. Su questi è applicata, in una prima fase, una procedura di ottimizzazione dei dispositivi, al fine di minimizzarne il numero e le dimensioni. Successivamente, i telai esaminati sono analizzati mediante analisi dinamiche incrementali (IDA) basate sull’uso di sette diverse registrazioni accelerometriche opportunamente selezionate e scalate. Sulla scorta dei risultati ottenuti sono quindi fornite indicazioni utili riguardanti, da un lato, il miglioramento della capacità sismica indotto dai diversi sistemi di protezione e, dall’altro, i valori del fattore di struttura da adottate per l’implementazione di analisi lineari convenzionali.

The current paper presents the first part of a study in progress devoted to analyse the St. Gemma church in Goriano Sicoli, which has been seriously damaged by the 2009 L'Aquila earthquake. Firstly, the main effects provoked by L'Aquila Earthquake on ancient historical centres, with particular regard to buildings belonging to the cultural heritage, are described. Then, the St. Gemma church is investigated in detail. The main geometry and structural details of the church are shown and damage occurred during to the seismic event of 6.04.09 is critically analysed and discussed. Finally, the main outcomes of dynamic tests carried out on the damaged church, in order to detect its main natural frequencies and mode shapes, are provided.

The current paper presents the results of a parametric analysis carried out on welded aluminium T-stub by means of FEM numerical models, which have been preliminarily calibrated on the basis of experimental tests. The study is carried out on 36 specimens conceived with different features and different types of bolts, in order to favour all possible collapse mechanism and to highlight the structural sensitivity of the T-stub system with respect to various mechanical and geometrical parameters. On the basis of the obtained outcomes, the reliability of the method presently available in EC9 is checked. The current paper represents a significant extension with respect to the experimental tests and numerical analyses carried out by the authors in the past.