1,721,022 research outputs found
Solidarizzazione di Muri Ortogonali tramite Barrette di AFRP: Modelli Analitici di Capacità e Riscontri Sperimentali
No full textLe costruzioni esistenti in muratura presentano talvolta strutture con muri ortogonali fra loro adiacenti ma non ammorsati convenientemente.
In caso di necessità di adeguamento sismico, può risultare utile accoppiare tali muri per aumentarne la rigidezza e la resistenza rispetto alle azioni orizzontali. Infatti, qualora il semplice consolidamento della muratura nel piano non sia sufficiente, l’accoppiamento dei muri può evitare di dover ricorrere all’inserimento di nuovi elementi strutturali. Un ulteriore vantaggio è poi rappresentato dall’incremento di stabilità dei singoli muri alle azioni trasversali.
In passato, interventi di questo tipo sono stati realizzati mediante l’impiego di iniezioni di malte cementizie o resine, armate con barre metalliche, che attraversano un muro trasversalmente e penetrano in profondità ancorandosi longitudinalmente nel secondo. Peraltro, tali interventi disturbano notevolmente la struttura muraria intima, arrivando anche a disgregarla localmente nella fase della perforazione, pur legandola di nuovo con la malta.
Si è quindi studiato e sperimentato un metodo di ammorsatura non distruttivo per il collegamento di due muri a T, operato con barrette sottili ( 5 ÷ 10 mm) di polimero rinforzato con fibra aramidica, che: a) attraversano in fori il muro “di ala”, secondo una inclinazione di ± 45°, b) si ancorano sulla faccia esterna di questo e lungo le superfici laterali del muro “di anima” mediante sfioccamento delle fibre e loro incollaggio sulla superficie muraria.
Il metodo, se dall’analisi strutturale risulta sufficiente il sistema dei muri collegati, permette di sfruttare i muri esistenti, senza aggiungerne di altri con le rispettive fondazioni.
Il programma delle prove comprende 3 muri già testati e altri 3 in fase di validazione sperimentale.
I campioni sono pannelli di muro alti circa 2 m, con due ali alle testate, realizzati in muratura a una testa. Essi sono stati sottoposti a prove quasi-statiche, con un carico verticale fisso e carico laterale alternato con cicli di ampiezza crescente.
Le prove condotte sul primo gruppo di campioni dimostrano l’efficacia della soluzione proposta, mentre i modelli analitici sviluppati in questa fase forniscono una buona stima degli incrementi di capacità flessionale
Stainless steel in chloride-contaminated concrete after carbonation
No full textTo minimize the consumption of natural resources for the concrete production, a possible solution is the use of chloride-contaminated raw materials. However, their use is forbidden for reinforced concrete structures, since they can promote the corrosion of carbon steel reinforcement. Within the SeaCon project “Sustainable concrete using seawater, salt-contaminated aggregates, and non-corrosive reinforcement”, financed by the Infravation program, the utilization of chloride-contaminated raw materials for the production of a sustainable concrete, when combined with stainless steel rebars, is studied. Preliminary results showed that different stainless steel types (austenitic and duplex) are suitable to be used in concretes made with chloride-contaminated raw materials and exposed outodoor (unsheltered) in the absence of further chlorides penetration. However, in time, carbonation can reach the bars and the corrosion behaviour of stainless steel might change. This paper focuses on the evaluation of the corrosion behaviour of stainless steel reinforcementin carbonated concrete
The use of recycled concrete for structural applications: state of the art, goals and perspectives
No full text
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
Numerical simulation of RC beams reinforced with FRCM
No full textFRCM (Fibre Reinforced Cementitious Matrix) system consists in two or more layers of cementitious mortar, in which a dry grid of fibres is disposed. This strengthening technique overcomes some of the limits of traditional systems, like FRP. Indeed, the presence of the mortar assures a better compatibility with the surface of the structural element, which could be either concrete or masonry. Moreover, FRCM can resist at higher temperatures and it can lead to a more ductile failure of the reinforced element. In this work, the attention is focused on the analysis of reinforced concrete (RC) beams retrofitted by FRCM. To this aim, both the behaviour of RC beams and of FRCM composite material is modelled through proper non-linear models implemented into a Finite Element (FE) code. The proposed approach is subsequently validated through significant experimental data relative to strengthened RC beams, available in technical literatur
Proceedings of Italian Concrete Days 2018 (ICD 2018)
No full textIn a dramatic car accident that occurred in January 2017, a touring coach hit at high speed one pillar of the highway overpass at the Verona-Est exit of the A4 motorway (Italy). This was followed by a violent fire that affected the support portal and part of the decking intrados, consisting of post-tensioned box beams. In order to assess the damage suffered by the structure, the effects of impact and exposure to high temperatures were analyzed separately.
Regarding the first issue, the numerical models of the bridge calibrated on the basis of dynamic characterization tests included the contribution of the inertial forces and the effect of the higher intensity of the impulsive force in the first stage of the impact. With reference to the effects of high temperature, a general survey and more detailed analyses have been carried out, using both traditional techniques and more advanced methods. This allowed forming a clear picture of the damage suffered, coordinated with the model-ling of the fire scenario
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
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