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Experimental study on injected anchors for the seismic retrofit of historical masonry buildings
Full text linkThe paper reports the results of a research on the behaviour of injected anchors in historical masonry under cyclic loads. Laboratory tests with masonry specimens (bricks and mortar with low characteristics to replicate real historical masonry) were conducted to analyse the response of steel anchors injected using a special sock and with different types of mortar (cement and lime based).
The test benches replicate the real condition of the use of these anchors: they allow to simulate the connection of masonry panels (T and L connections) or the anchor of steel ties to contrast the arch thrust. Monotonic and cyclic pull out tests were conducted on short and long anchors to define the loss of strength under cyclic loads for different situations.
The results allowed to obtain: load-displacement graphs; steel bar deformation graphs on anchors’ length; a qualitative bond stress curve; comparison among maximum strengths obtained under several conditions
Pre-stressed vertical injected anchors on historical masonry: a case study, the Bell Tower of Botta di Sotto il Monte Papa Giovanni XXIII
No full textThe Bell Tower of the Church "Sacro Cuore Gesù e S. Egidio Abate" in Sotto il Monte (Bergamo, Italy), represents a case study of the research programme "ANIMUS", funded by the European Programme FESR-2007-2013. The necessity of building a steel belfry on top of the bell tower required a detailed study of its connection with the supporting masonry structure. This connection has been realized by means of deep vertical anchors, obtained by grouting steel bars by injecting the grout in special socks, such that any dispersion of the mortar in the masonry is avoided. By this technique, a "bulb" creating an effective interlock with the masonry structure is created. The behaviour of the system has been studied by means of a finite element model, allowing to assess the performance of the connection under wind and seismic loads both at service and ultimate limit states. The results have highlighted the opportunity to design vertical anchors with a double bulb of mortar. This way, by grouting the deeper bulb soon after installation, the anchor could be pre-stressed to avoid any decompression of the connection between the superstructure and the masonry tower under service loads. The upper bulb, grouted at a later time, has the role of transferring the loads exceeding serviceability limit state to the masonry structure. After the installation of vertical anchors, an experimental phase started with the execution of cyclic tests, thus allowing to evaluate the effectiveness of the intervention and to compare experimental and numerical results
Ancoraggi iniettati per il rinforzo sismico di edifici storici in muratura: prove di estrazione monotone e cicliche
No full textLa presente memoria riporta i risultati ottenuti durante una campagna sperimentale in labo- ratorio volta ad indagare il comportamento di ancoraggi iniettati in muratura storica realiz- zati mediante l’utilizzo di speciale calza in tessuto a contenimento della malta iniettata per rendere solidale l’elemento di rinforzo in acciaio alla muratura. I vantaggi che derivano dall’impiego di questa tecnologia innovativa riguardano sia la salvaguardia dei manufatti di interesse storico-architettonico, l’iniezione controllata permette infatti di evitare dispersione all’interno di cavità ed interstizi delle murature, sia l’efficacia strutturale dell’ancoraggio, grazie ai meccanismi di aderenza e ingranamento che si vengono a sviluppare con il substrato.
In particolare saranno presentati i risultati ottenuti da prove di estrazione monotone e cicliche effettuate in laboratorio su ancoraggi profondi iniettati in direzione longitudinale, e quindi nel piano del paramento murario, iniettati con due differenti tipologie di malta a confronto, a base cementizia e a base calce.
I dati ottenuti hanno consentito la costruzione di grafici forza spostamento da cui è stato possibile ricavare, per tutte le prove, il massimo valore di carico, che si è deciso di identificare come il punto di “collasso” del sistema, ed il relativo valore di spostamento, sia riferito al bulbo di malta che alla barra di acciaio
Injected Anchors For The Seismic Retrofit Of Historical Masonry Buildings: Experimental Study On Brick Masonry
No full textThe paper reports the results of a research on the behaviour of injected anchors in historical masonry under cyclic loads. Tests in laboratory with masonry specimens (bricks and mortar with low characteristics to replicate a real historical masonry) were conducted to analyse the response of steel anchors injected with a special sock and with different sorts of mortar (cement and lime based).
The test benches replicate the real condition of the use of these anchors: to connect masonry panels (T and L connections) or to anchor steel ties to contrast the arch thrust. Monotone and cyclic pull out tests were conducted on short and long anchors (injected orthogonally and lengthwise to the masonry main plane) to compare the results and to define the loss of strength under cyclic loads for different situations.
The results allowed to obtain: 1) construction of load-displacement graphs, up to the maxi- mum load value (maximum strength) of each anchor and the related displacement; 2) steel bar deformation graphs on the length of the anchors (thanks to the strain gauges installed on steel bars) at different values of load and under cyclic loads; 3) qualitative bond stress curve derived from the steel bar strains, which allowed to investigate the behavior of the anchors along the bar length under cyclic loads
Injected Anchors For The Seismic Retrofit Of Historical Stone Masonry Buildings: In Situ Experimental Tests
No full textThe paper reports the results of a research on the behaviour of injected anchors in historical masonry under cyclic loads. Monotonic and cyclic pull-out in situ tests were conducted on historical stone masonry to analyse the response of anchors injected orthogonally to the masonry main plane and at different heights to evaluate also the effect of different values of normal confinement on the anchor behaviour. Moreover the tests were conducted on anchors of different length, instrumented with strain-gauges. The aim was to investigate the loss of strength under cyclic loads. The results allowed: 1) construction of load-displacement graphs, up to the maximum load value (maximum strength); 2) steel bar deformation graphs on the length of the anchors at different values of load, under cyclic loads; 3) qualitative bond stress curve, derived from the steel bar strains, to investigate bond behavior along the bar length
Metodologie semplificate per la stima delle vulnerabilità sismica di edifici industriali
No full textBuona parte degli edifici industriali esistenti è stata costruita in assenza di una normativa sismica specifica. I fabbricati generalmente non presentano i dettagli costruttivi necessari ad assicurare un’adeguata resistenza e duttilità degli elementi strutturali e delle connessioni, non essendo di fat- to concepito uno schema statico basato sui moderni principi di gerarchia delle resistenze. In ag- giunta i complessi industriali sono spesso caratterizzati dalla presenza di molteplici unità struttu- rali indipendenti con grande estensione in pianta, a loro volta costituite da un numero molto ele- vato di elementi strutturali, composti da elementi assemblati tra cui elementi reticolari, tralicciati e calastrellati. Ciò rende onerosa la valutazione della vulnerabilità sismica dell’edificio e del complesso industriale utilizzando approcci tradizionali di analisi di vulnerabilità sismica.
Per una prima stima della vulnerabilità sismica si può far ricorso a modelli semplificati. Nel pre- sente articolo viene presentato un modello planare che prevede la definizione di pochi elementi che rappresentano il sistema di controventamento, in grado di ridurre i gradi di libertà e la com- plessità del modello e di velocizzare l’analisi delle strutture. Tale procedura semplificata è stata applicata a un caso studio per valutarne l’efficacia e l’affidabilità.Most of the existing industrial buildings were built with no specific seismic regulations. Generally, such structures do not present the details needed to ensure an adequate strength and ductility for both structural elements and connections, since a static scheme based on modern principles was not actually conceived nor capacity design was applied. In addition, industrial buildings are often characterised by the presence of multiple independent structural units with a large plant extension and by the presence of a very large number of structural elements consisting of assembled elements such as lattice beams and laced or battened columns. This makes the seismic vulnerability assessment difficult and time consuming if traditional analysis approaches are followed.
Simplified models can be used for a first estimate of the seismic vulnerability. In this article, one model is analyzed: a planar model that includes the definition of a few elements that represent the bracing system. Such model is able to reduce the degrees of freedom and the complexity of the analysis, decreasing the computational effort. The simplified procedure has been applied to a case study to evaluate the accuracy of the results and the reliability of the method
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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