Studio sperimentale del comportamento dinamico di murature multistrato in pietra rinforzate mediante iniezioni e tiranti. (Experimental study on the dynamic behaviour of multi-leaf stone masonry walls reinforced through injections and transversal steel ties)

Questa tesi presenta i risultati sperimentali di una campagna di prove dinamiche volte ad indagare il comportamento di murature storiche di pietra a tre parametri, a seguito di due differenti tecniche d'intervento di rinforzo (iniezione di miscela a base di calce idraulica naturale e applicazione di tirantini antiespulsivi nella sezione). Le prove fuori-piano effettuate su singoli elementi strutturali verticali (dimensioni m. 2.60x1.30x0.50) sono state condotte presso il laboratorio Enea "La Casaccia". La tesi fornisce inoltre l'identificazione dinamica degli stessi modelli svolta con Macec, ottenendo così informazioni in termini di frequenze proprie, forme modali e rapporti di smorzamento

“Data BAES - Correlazione vulnerabilità e danno tra Beni Artistici ed Elementi Strutturali" / "Data BAES - Correlation of vulnerability and damage between Artistic Assets and Structural Components”

DataBAES è il primo archivio che raccoglie dati delle componenti strutturali e beni artistici in modo integrato, in relazione alla vulnerabilità e danno rilevabili negli edifici in muratura di interesse storico-artistico in situazione di pre e post-sisma. I dati sono raccolti in sito mediante schede di rilievo che fanno riferimento agli attuali strumenti schedografici (Scheda A-DC, B-DP, C-BM) e alle raccomandazioni o classificazioni disponibili in letteratura (EMS 98, UNI EN 1182:2006), estendendone l’impiego e realizzando uno strumento tecnico per identificare la pianificazione della conservazione del patrimonio sul territorio. L’archivio dati è composto da casi studio intesi come apparati decorativi fissi (dipinti murali, stucchi, mosaici) e propri elementi strutturali di supporto (pareti, volte, pilastri). Il database dei casi studio è accessibile online. E' necessario creare un'account per inserire nuovi casi studio utilizzando le schede di rilievo disponibili in pdf insieme alla guida di compilazione. DataBAES is the first archive which collects information on structural components and artistic heritage in terms of the weak points in the masonry, as well as on obvious damage done to them before and after earthquakes strike. The information is collected onsite via survey forms, which employ current maps as well as recommendations and classifications (EMS 98, UNI EN 1182:2006). These forms can be accessed in written form, providing a technical means by which the best methods for conserving the heritage in an area can be planned. The archive of information consists of intensive case studies of subjects such as decorative devices (e.g. paintings, plaster and mosaics), and genuine structural elements which support the building (e.g. walls, vaults and pillars). The access to case studies is free. An account is needed to insert and manage new case studies (survey forms and instructions will be available to users in PDF format)

Shaking table testing of as-built and retrofitted clay brick URM cavity-walls

Masonry cavity-wall construction incorporates a continuous air gap that separates the inner and outer brick leaves of the wall cross-section. This wall configuration was originally developed because of improved thermal performance and in particular reduced moisture transmission across the wall, as the presence of the air-cavity serves to capture and drain moisture back to the building exterior. However, it was subsequently established that clay-brick unreinforced masonry (URM) cavity-wall buildings typ- ically exhibit poor seismic performance due to inadequate connections between the separate masonry leaves in the wall cross-section. Experimental shaking table testing of five cavity-walls was undertaken with an emphasis on developing and experimentally validating simple and efficient retrofit solutions to improve cavity-wall seismic capacity. Wall specimens closely simulated in-situ conditions for the URM cavity-wall arrangements that are most commonly encountered in New Zealand. Two different retrofit solutions were tested, namely, the addition of mechanical screw-ties with different spacings or a combi- nation of mechanical screw-ties and timber strong-backs. Specimen construction details, retrofit proce- dures, test set-up and results are presented herein. Reported results include observed crack-patterns, peak ground acceleration (PGA) corresponding to both induced initial cracking and failure, acceleration and displacement profiles at failure, and quantification of the improvement in seismic capacity from using the proposed retrofit techniques

Edilizia storica monumentale - Salvaguardia degli edifici di interesse storico-artistico nell\u2019emergenza post-sisma

Gli eventi sismici che hanno colpito un\u2019ampia fascia immediatamente a nord di Bologna, tra Ferrara, Mantova, Reggio Emilia, lambendo anche Mantova e Rovigo, hanno avuto effetti, in termini di scuotimento del suolo, molto inferiori a quelli provocati dal terremoto dell\u2019Abruzzo, con conseguenze molto pi\uf9 selettive. I danni strutturali si sono infatti manifestati, anche con gravi ed estesi crolli, pressoch\ue9 esclusivamente su due sistemi edilizi, evidentemente i pi\uf9 vulnerabili: l\u2019edilizia storico/monumentale e gli edifici industriali. Le attivit\ue0 di salvaguardia del patrimonio architettonico di interesse culturale si sono svolte facendo ampio ricorso alle precedenti esperienze, ma secondo un nuovo e diverso modello di gestione dell\u2019emergenza, facente capo direttamente al MIBAC. Sono state istituite: l\u2019Unit\ue0 di Crisi-Coordinamento Nazionale (UCCN-MiBAC) per il coordinamento generale, e le Unit\ue0 di Crisi-Coordinamento Regionale (UCCR-MiBAC) facenti capo ai Direttori Regionali territorialmente competenti, per il coordinamento e lo svolgimento delle attivit\ue0 sul campo. Il rilievo del danno \ue8 stato effettuato con le stesse modalit\ue0 operative utilizzate in seguito al terremoto de L\u2019Aquila (6 Aprile 2009), mediante la sistematica compilazione di specifiche schede per chiese e palazzi predisposte dalla Protezione Civile (Gruppo di Lavoro Beni Culturali \u2013 GLABEC). Le squadre compilatrici sono composte da tecnici della Sovrintendenza, funzionari dei Vigili del Fuoco e, quando necessario, da una tecnico con competenza specifica sulla tipologia di beni culturali presenti nell\u2019edificio. Nelle stesse schede, vengono fornite le indicazioni necessarie per gli interventi di messa in sicurezza, successivamente progettati ed eseguiti, nella maggior parte dei casi, dai Vigili del Fuoco impegnati contemporaneamente sul fronte, nuovo rispetto all\u2019Abruzzo e di evidente straordinaria importanza socio-economica, della limitazione delle perdite e dei danni all\u2019apparato produttivo delle zone colpite dal terremoto. Un effetto di particolare criticit\ue0, in relazione alle attivit\ue0 di salvaguardia del costruito storico, connesso con la selettivit\ue0 del danno di cui si \ue8 sopra accennato, \ue8 stato il fatto che: nonostante la maggioranza degli edifici adibiti a residenza e/o alle normali attivit\ue0 commerciali di un centro abitato siano risultati immediatamente agibili, il centro o il quartiere venivano dichiarati inagibili per il pericolo indiretto causato dalla presenza di un campanile e/o di una chiesa fortemente danneggiati. A fronte quindi di un quadro globale di danno strutturale inferiore a quello riscontrato in Abruzzo, la gestione dell\u2019emergenza post-sisma \ue8 risultata in generale non meno complessa e impegnativa, e la selettivit\ue0 del danno \ue8 stato un fattore di complicazione, e non di semplificazione, soprattutto per quanto riguarda le attivit\ue0 di salvaguardia dei beni architettonici

Out-of-plane shake-table tests of strengthened multi-leaf stone masonry walls

Existing unreinforced multi-leaf stone masonry (URM) buildings are one of the most earthquake prone types of construction. Failure typically occurs even at low levels of earthquake-induced loads, with the out-of-plane delamination of masonry leaves and consequent collapse of the whole fac\ub8ade. Although this issue has been tackled by several researchers, dynamic tests reproducing the earthquake behaviour of as-built and strengthened multi-leaf stone URM walls are very limited in the literature. In response to this lack, shake-table testing of eight full-scale multi-leaf stone masonry walls followed by dynamic modal identification was performed. The application of steel tie-rods in the wall cross-section, the injection of the inner-core using hydraulic lime-based grout, and a combination of the two techniques are presented herein as suitable interventions to enhance the monolithic behaviour of multi-leaf stone URM walls. Tying the outer masonry leaves together increased the seismic capacity by a factor of 1.8 compared to unreinforced condition, while injecting grout into the inner-core of the wall provided resistance to peak ground acceleration (PGA) that were 2.3\u20133.6 times the PGA resisted by as-built walls, depending on the quality in the execution of the intervention. The results obtained in the walls strengthened with both techniques were significantly related to the grout injection only

Dynamic modal identification of strengthened three-leaf stone masonry walls subjected to out-of-plane shaking table tests

Dynamic monitoring and the subsequent dynamic identification of structures represent one of the most important non-destructive techniques to deepen the knowledge about their seismic behaviour. The results of a dynamic identification of the data collected during an experimental campaign on eight full scale three-leaf masonry walls tested on shaking table are presented. The walls were tested under out-of-plane dynamic actions using a shaking table. The influence of retrofitting interventions is compared considering grout injection, transverse tying and a combined solution of the two techniques. This allowed the frequencies, mode shapes and damping factors of each wall to be identified. A comparative evaluation of results obtained on different conditions allowed the different effects on the overall behaviour to be identified

Constituent material properties of New Zealand unreinforced stone masonry buildings

Most of New Zealand’s stone unreinforced masonry (URM) building stock was constructed between 1860 and 1910 by early European settlers, with approximately 670 stone URM buildings remaining throughout the country. These buildings are typically classified as earthquake-prone, indicating that they require seismic strengthening in order to avoid demolition as a seismic hazard. Practitioners and industry professionals currently lack knowledge about the traditional construction techniques used for these buildings, and about suitable methods for improving their seismic performance. To address this knowledge gap, research was conducted to classify the constituent materials used in the original construction and to document the mechanical and physical characteristics of these construction materials. Extraction of structural mortar and natural stone samples was undertaken in buildings that were deemed to be representative of the New Zealand stone URM building stock, and X-Ray Powder Diffraction (XRPD) and petrographical analyses were performed on these samples respectively in order to identify mineral composition and their original source location. In addition, the compressive strength of extracted material samples was determined. A database of New Zealand natural stones that were typically used by the early European settlers in construction, including the source and compressive strength of each stone sub-type, is summarised herein. The presented data is intended to facilitate the selection of compatible materials and suitable techniques for repair and seismic retrofit of vintage stone URM buildings

Construction Details and Observed Earthquake Performance of Unreinforced Clay Brick Masonry Cavity-walls

none4siUnreinforced masonry (URM) cavity-wall construction is a form of masonry where two leaves of clay brick masonry are separated by a continuous air cavity and are interconnected using some form of tie system. A brief historical introduction is followed by details of a survey undertaken to determine the prevalence of URM cavity-wall buildings in New Zealand. Following the 2010/2011 Canterbury earthquakes it was observed that URM cavity walls generally suffered irreparable damage due to a lack of effective wall restraint and deficient cavity-tie connections, combined withweak mortar strength. It was found that the original cavity-ties were typically corroded due to moisture ingress, resulting in decreased lateral loadbearing capacity of the cavity-walls. Using photographic data pertaining to Christchurch URM buildings that were obtained during post-earthquake reconnaissance, 252 cavity-walls were identified and utilised to study typical construction details and seismic performance. The majority (72%, 182) of the observed damage to URM cavity-wall construction was a result of out-of-plane type wall failures. Three types of out-of-plane wall failure were recognised: (1) overturning response, (2) one-way bending, and (3) two-way bending. In-plane damage was less widely observed (28%) and commonly included diagonal shear cracking through mortar bed joints or bricks. The collected data was used to develop an overview of the most commonly-encountered construction details and to identify typical deficiencies in earthquake response that can be addressed via the selection and implementation of appropriate mitigation interventions.mixedGiaretton, Marta; Dizhur, Dmytro; da Porto, Francesca; Ingham, Jason M.Giaretton, Marta; Dizhur, Dmytro; DA PORTO, Francesca; Ingham, Jason M

Seismic assessment and improvement of unreinforced stone masonry buildings: Literature review and application to New Zealand

Following the 2010/2011 Canterbury earthquakes considerable effort was applied to the task of developing industry guidance for the seismic assessment, repair and strengthening of unreinforced masonry buildings. The recently updated \u201cSection 10\u201d of NZSEE 2006 is one of the primary outputs from these efforts, in which a minor amount of information is introduced regarding vintage stone unreinforced masonry (URM) buildings. Further information is presented herein to extend the resources readily available to New Zealand practitioners regarding load-bearing stone URM buildings via a literature review of the traditional European approach to this topic and its applicability to the New Zealand stone URM building stock. An informative background to typical stone URM construction is presented, including population, geometric, structural and material characteristics. The European seismic vulnerability assessment procedure is then reported, explaining each step in sequence of assessment by means of preliminary inspection (photographic, geometric, structural and crack pattern surveys) and investigation techniques, concluding with details of seismic improvement interventions. The challenge in selecting the appropriate intervention for each existing URM structure is associated with reconciling the differences between heritage conservation and engineering perspectives to reinstating the original structural strength. Traditional and modern techniques are discussed herein with the goal of preserving heritage values and ensuring occupant safety. A collection of Annexes are provided that summarise the presented information in terms of on-site testing, failure mechanisms and seismic improvement

An inventory of unreinforced load-bearing stone masonry buildings in New Zealand

Almost all unreinforced stone masonry (URSM) buildings in New Zealand were constructed between 1860 and 1910, typically in regions where natural stone was sourced from local quarries, fields and rivers. These buildings form an important part of the country\u2019s architectural heritage, but the performance of URSM buildings during earthquake induced shaking can differ widely due to many aspects related to the constituent construction materials and type of masonry wall cross-section morphology. Consequently, as a step towards gaining greater knowledge of the New Zealand URSM building stock and its features, an exercise was undertaken to identify and document the country-wide URSM building inventory. The compiled building inventory database includes: (i) general building information, such as address, building owner/tenant and building use; (ii) architectural configuration, such as approximate floor area, number of storeys, connection with other buildings, plan and elevation regularity; and (iii) masonry type, such as stone and mortar types, wall texture and wall cross-section morphology. From this exercise it is estimated that there is in excess of 668 URSM buildings currently in existence throughout New Zealand. A large number of these vintage URSM buildings require detailed seismic assessment and the implementation of seismic strengthening interventions in order to conserve and enhance this component of New Zealand\u2019s cultural and national identity. The entire stock of identified buildings is reported in the appended annex (688 total), including 20 URSM buildings that were demolished following the Canterbury earthquake sequence