RIVISTA della STAZIONE SPERIMENTALE DEL VETRO gennaio/marzo 2014 - n. 1 vol. 44 sommario In questo numero ........................................... 2 Manifestazioni ............................................... 23 Riassunti ............................................................... 3 12th ESG Conference ............................... 29 Studi Dal mondo del vetro Lavori di restauro nella chiesa di Sant’Aniello a Caponapoli ........................................ 5 Restoration and arrangement of Sant’Aniello at Caponapoli Church Ugo Carughi a cura di Erica Ladogana .................................. 30 Agenda ................................................................. 42 Una nuova soluzione ibrida per travi strutturali in vetro rinforzato ......................... 9 A new hybrid solution for structural glass reinforced beams Michel Palumbo, Dominque Palumbo, Teresa Mazzucchelli Processi di ottimizzazione nei cicli di recupero del rottame di vetro - il macinato di KPS GLASS Optimization processes in glass cullet re-cycling: ground KPS GLASS ................................................... 14 Alessio Bonetto, Piero Daminato Direttore responsabile Stefano Manoli Redazione Erica Ladogana email: [email protected] Impaginazione e grafica Betti Bertoncello Direzione e Redazione - Proprietà Stazione Sperimentale del Vetro S.c.p.A. Via Briati 10 - 30141 Murano (VE) Tel.: +39 041 2737011 Fax: +39 041 2737048 email: [email protected] http:/ / www.spevetro.it Autorizzazione del Tribunale di Venezia n. 271 in data 23.01.1971 R.O.C. 3913 Rivista trimestrale associata alla Unione Stampa Periodica Italiana Istruzioni per gli Autori La Rivista pubblica studi, ricerche ed esperienze sulla tecnologia e sulla scienza del vetro e i materiali ad esso collegati. Chiunque può mandare elaborati, memorie ecc. La Redazione si riserva o meno la loro pubblicazione. I testi, corredati da un breve riassunto di circa dieci righe, in italiano e inglese, dovranno pervenire in forma elettronica (preferibilmente in Microsoft Word). Immagini e tabelle dovranno essere in file separati: le immagini preferibilmente in formato tif o jpg (minimo 300 dpi); le tabelle in Microsoft Excel o Microsoft Word. La Rivista diventa proprietaria dei lavori pubblicati e questi non possono essere riprodotti altrove senza autorizzazione. I testi accettati per la pubblicazione saranno considerati definitivi. Eventuali sostanziali variazioni dovranno essere concordati con la Redazione. La Direzione è estranea alle tesi sostenute nei loro articoli dai singoli collaboratori. Questi assumono la piena responsabilità dei loro scritti. È vietata la riproduzione, anche parziale, dei testi e delle illustrazioni senza la preventiva autorizzazione della Redazione. 1 1-2014 in questo numero Rivista della Stazione Sperimentale del Vetro In questo numero della Rivista della Stazione Sperimentale del Vetro concludiamo la pubblicazione dei lavori presentati al seminario ATIV tenutosi nel mese di novembre 2012 nella sessione vetro piano. Gli articoli pubblicati sono: “Restoration and arrangement of Sant’Aniello at Caponapoli Church” di Ugo Carughi, a pag. 5, e “A new hybrid solution for structural glass reinforced beams” a firma Palumbo, Palumbo, Mazzucchelli, a pag. 9. Il terzo articolo che presentiamo ai nostri lettori è “Processi di ottimizzazione nei cicli di recupero del rottame di vetro - il macinato di KPS GLASS”, di Alessio Bonetto e Piero Daminato (Eco-Ricicli Veritas srl): il lavoro presenta l’esperienza maturata dagli autori nell’ambito dell’ottimizzazione del recupero del rottame di vetro cavo. In particolare, si descrive il processo di trattamento del materiale scartato nel ciclo di produzione del vetro pronto forno (VPF) e il processo tecnologico per il recupero di materiale da re-immettere nel ciclo di produzione del VPF o da destinare ad altre applicazioni, quali ad esempio quella per l’edilizia (pag. 14). Ricordo ai nostri lettori l’appuntamento con la Conferenza ESG - a Parma dal 21 al 24 settembre 2014 - che la Stazione sta organizzando insieme ad ATIV. Le numerose adesioni di tecnici e studiosi del vetro e i positivi riscontri sin qui raccolti dalle aziende vetrarie e della filiera sono per noi motivo di soddisfazione e testimoniano l’interesse intorno ai sei temi che saranno proposti nelle giornate della manifestazione: tecnologia vetraria, vetro e ambiente, proprietà e misure, vetri speciali, sicurezza ed igiene, vetro in architettura. Sono stati raccolti circa 200 lavori tra presentazioni orali e poster. Per iscriversi alla conferenza e per qualsiasi altra informazione è on-line il sito www.esg2014.it Con la pubblicazione di questo primo numero del 2014, desidero ringraziare il Dottor Antonio Tucci, per molti anni Direttore Responsabile della Rivista, che con il 2013 ha concluso la collaborazione con la Stazione Sperimentale del Vetro: il suo impegno, la sua determinazione e lo stile della sua conduzione hanno valorizzato questa pubblicazione che, nata oltre 40 anni fa, resta un riferimento importante tra le riviste nazionali a contenuto tecnico-scientifico sul vetro. Spero di poter dare continuità al suo lavoro con la medesima qualità. Stefano Manoli 2 summaries riassunti Lavori di restauro nella chiesa di Sant’Aniello a Caponapoli Restoration and arrangement of Sant’Aniello at Caponapoli Church Ugo Carughi Riv. Staz. Sper. Vetro 44 (2014), 1, p. 5-8 Una nuova soluzione ibrida per travi strutturali in vetro rinforzato A new hybrid solution for structural glass reinforced beams Michel Palumbo, Dominque Palumbo, Teresa Mazzucchelli Riv. Staz. Sper. Vetro 44 (2014), 1, p. 9-13 Rivista della Stazione Sperimentale del Vetro La chiesa di Sant’Aniello a Caponapoli, situata sull’Acropoli dell’antica Neapolis, risale ai primi decenni del XVI secolo. Dopo essere stata danneggiata dai bombardamenti nel 1944, fu abbandonata per due decenni, soffrendo di saccheggi e danneggiamenti. Negli anni ’60 il tetto e il nartece (atrio) esterno furono ricostruiti. Alcuni monitoraggi, seguiti da scavi più estesi, rivelarono importanti scoperte, che furono studiate e documentate nell’attuale contesto. The Church of Sant’Aniello at Caponapoli, located on the acropolis of the ancient Neapolis, dates back to the early decades of the Sixteenth Century. After being damaged by bombing in 1944, it was abandoned for two decades, suffering relevant damage and despoliation. In the 1960s the roof and the exornarthex were rebuilt. Some tests, followed by extensive excavations, reveled important finds, that were studied and documented in the constest of the current arrangement. In genere, la progettazione di travi in vetro segue due approcci principali: • il primo è basato su travi stratificate costruite a partire da elementi in vetro temprato, per massimizzare la capacità di ogni singolo elemento di sostenere il carico. In questo caso, maggiore la resistenza teorica, inferiore la sicurezza in caso di rottura; • il secondo, invece, è basato sull’idea dell’autore (brevettata all’inizio degli anni 2000) di rinforzare una trave costituita da lastre di vetro ricotto, in modo da garantire, nell’eventualità di un danneggiamento del vetro, la sopravvivenza dopo il picco di carico degli elementi in vetro, che manterranno le loro caratteristiche di resistenza al carico anche se gli strati di vetro vengono danneggiati. Nel presente articolo si descrive un terzo approccio ibrido alla stratificazione della trave in vetro, in grado di raggiungere importanti obiettivi. Usually there are two main ways to design glass beams: • The first is based on layered beams made of fully tempered glass elements to maximise the potential of the load bearing element. In this case, the higher the theoretical resistance, the lower the safety in case of glass breakage; • The second, instead, is based on the authors’ idea (patented in the early 2000s) to reinforce an all-glass beam made of annealed glass sheets to guarantee, in the event of glass damage, the postpeak life of the glass elements, which will maintain their load bearing properties even if the glass layers are damaged. We herewith describe a third hybrid glass beam layup that meets important goals. 3 1-2014 summaries riassunti 1-2014 Processi di ottimizzazione nei cicli di recupero del rottame di vetro - il macinato di KPS GLASS Optimization processes in glass cullet re-cycling: ground KPS GLASS Alessio Bonetto, Piero Daminato Riv. Staz. Sper. Vetro 44 (2014), 1, p. 14-22 Rivista della Stazione Sperimentale del Vetro Il presente lavoro intende presentare l’esperienza maturata nell’ambito di Eco-Ricicli Veritas srl (ERV) nell’ottimizzazione del recupero di rottame di vetro cavo. In particolare, si vuole esporre il processo elaborato nell’ambito del trattamento del rottame di scarto del ciclo di produzione del vetro pronto forno (VPF). Nell’ambito di tale ciclo, infatti, soprattutto nella fase di selezione ottica del materiale, viene scartata una frazione, granulometricamente eterogenea, composta da refrattari, lapidei, ma anche rottame di vetro scuro o sporco, con presenza di materiale plastico. L’eterogeneità di tale materiale rende ostico sia il recupero che lo smaltimento. In un’ottica di aumento delle prestazioni di recupero, ERV ha elaborato un processo tecnologico che da tale flusso recupera rottame di vetro impropriamente presente per errore strumentale e lo reimmette nel ciclo di produzione del VPF, mentre il materiale restante viene trasformato in un prodotto utilizzabile o direttamente in settori quali l’edilizia, o gestibile in ulteriori cicli di recupero di tipo industriale, risparmiando il ricorso a materie vergini da cava. Il processo tecnologico consta nella riduzione granulometrica del materiale, la rimozione di corpi estranei leggeri (plastiche, organico), il materiale risultante è configurabile come una graniglia silicea che ai test ha rivelato buone doti sia come materiale per sottofondi come parziale sostituto di sabbie vergini, che come materiale per rilevati in miscelazione ad argille. Al vaglio sono attualmente ulteriori test per l’impiego in altri settori tecnologici. This work aims to show the experience built up in Eco-Ricicli Veritas srl (ERV) about the optimization of hollow glass recovery. More precisely, it will be elucidated the treatment applied to the reject of the furnace-ready cullet process. In this process, during the optical screening of the input material a reject is obtained, composed of stones, bricks, ceramic, dark glass and plastic material of variable grain size. The miscellaneous composition of this reject makes the recovery as well as the disposal very difficult. In the light of an increase of glass recovery, ERV has applied a technological improvement to the sorting process which recovers glass cullet incorrectly present in the rejected material and puts it back in the Furnace-ready cullet treatment process. The remaining material is then transformed for direct use in building industry, or in other type of industrial recovery process, saving some amount of virgin raw material. The technological process consist in the grain size reduction of the material and the removal of light materials (plastic, organic). The material obtained is a silica-like coarse sand, which has been tested for the use as partial replacement as background material for road pavements, and mixed with clay for street’s building. Further tests are under way to check the use of this material in other technological and industrial fields. 4 studies studi Rivista della Stazione Sperimentale del Vetro Restoration and arrangement of Sant’Aniello at Caponapoli Church Ugo Carughi Historical aspects and status of the building The urban area of Caponapoli is at the highest point of the Greek town and occupies the inner corner defined by the northern and eastern limits of the original nucleus of Neapolis; these limits are still identifiable today - although with approximation with via Foria to the north and via Costantinopoli to the west. The original setting resulted from the necessity of defense, as testified by the successive lines of defensive walls of Greek time discovered beneath the church, located in the highest point of the hill and following a North-West / South-East axis, roughly parallel to the present via Foria. In this area also stood other important religious buildings dedicated to the cult of Diana, Apollo and Ceres, where solemn rites took place with processions and sacrifices. During roman times the area was chosen by patrician families for their dwellings and consequently lost its exclusively religious character. Defensive structures were a still a dominant feature in Angevin times and during the Spanish viceroyalty. The new defensive walls built by don Pedro de Toledo at the foot of the hill, in front of the ravine where the gushing water of Vergini flew, defined a new configuration of the area and as a consequence of the filling between the hill and the new walls the area was extended north of the fortified plateau. Following the large transformations of the last century, the once sacred hill is now dominated by the large buildings of the University hospitals, whilst many religious buildings have been subject to refurbishment and demolition. The area was a real monastic citadel when, during the Sixteenth Century, a large nave was built extending the Church of Sant’Aniello, originally dedicated to the Virgin Mary in the Sixth Century and subsequently consecrated to Santa Maria Intercede, to commemorate the birth of the Abbot Agnello. The Church of Sant’Aniello at Caponapoli, located on the acropolis of the ancient Neapolis, dates back to the early decades of the Sixteenth Century. After being damaged by bombing in 1944, it was abandoned for two decades, suffering relevant damage and despoliation. In the 1960s the roof and the exonarthex were rebuilt. Some tests, followed by extensive excavations, revealed important finds, that were studied and documented in the context of the current arrangement: three successive parallel walls of the III Century BC Greek city, which acted as retaining walls for the ridge sloping to the present Piazza Cavour, were found in the nave and one in the transept, behind the high altar. Roman walls made of opus reticulatum dating from the First Century AD, intersected with tombs of the Early Middle Ages, were also found. Close to the high altar, there are traces of the apse belonging to an early Christian chapel. Under some chapels - that can now be visited - typical tombs with “draining” seats were discovered. A multitude of marble pieces found in the church have been rearranged, as in a giant puzzle, following their detailed reconnaissance, survey and filing. The religious complex of Sant’Aniello, which forms part of the nearby monastery, was completed during the Sixteenth Century and includes many residential buildings; for more than two centuries it represented one of the major testaments of devotion to 5 1-2014 studies studi 1-2014 Sant’Aniello, whose cult in Naples is second only to San Gennaro. The construction of the complex was carried out for an unknown number of years until the Eighteenth Century, with consecutive orna- 6 Rivista della Stazione Sperimentale del Vetro mentation and restoration, whilst the private chapels were enriched, particularly during the Sixteenth and Seventeenth Century, with marble sculptures and paintings. studies studi Restoration works In 1962 the Soprintendenza ai Monumenti di Napoli started the first works of strengthening and restoration that required the reinstatement of the roof and of the exonarthex and the strengthening of the external walls. Following the archaeological excavation beneath the nave in the 1970s the floor was dismantled and subsequently replaced with large steel beams supporting a metal deck with reinforced concrete topping. As part of the same works all the walls were strengthened with reinforced pressure grouting (this technique is no longer used for monumental buildings). During the 1980s and 1990s, due to the sporadic and meager ministerial funding assigned to the church, countless and discontinuous works of strengthening and restoration were carried out, both internally and externally. At the beginning of the 3rd Millennium the interior has been rearranged; insofar as possible every surviving marble and pictorial fragments have been recomposed; the archaeological finds have been restored and arranged below ground level; the baluster of the chancel and altar platforms and gradinos have been restored and located in the transept where other marble elements of uncertain location have been exhibited. The project provided the opening of a rectangular void (9.65m x 5.15m) in the reconstituted floor of the nave, with passages of adequate width between the edges of the void and the side chapels. This arrangement allowed to have inside the church a synchronic view of the whole history of the city, from its founding to contemporary times, through the exhibit of finds that are distant in time but close in space. On the other hand, unlike the archaeological sites of the Cathedral and of San Lorenzo Church, here the extremely variable archaeological layers would have not allowed an independent visit. From the nave, through an intermediate step, it is possible to get to a continuous structural glass walk- Rivista della Stazione Sperimentale del Vetro way located along the inner perimeter of the great void, at level -0.40m. The walkway is supported by structural glass beams, about 2.00m long, attached to steel beams set back from the edge of the void, that support the nave floor. Steel corners fixed to the cantilevered perimeter of the nave floor halve the free span of the glass beams. There are no other examples, at least in Italy, of similar glass cantilevered beams. The clear glass balustrade is point fixed to the free ends of the glass beams and both the balustrade and the walkway have been cut from 6.00m long bars into demountable modules of 1.5m. Wooden benches are placed on a wooden platform built on the “cocciopesto” floor. Among the benches, those placed parallel to the longer sides of the void are formed of two seats that can rotate around a steel pin with a stop and can be manually positioned in two different orientations. When these seats are in a transverse position, a mechanism allows the backs to rotate and become a worktop for those sitting on the bench behind. Size, number and position are determined by the optimum width for the worktop and the platform width (1.40m), which, in turn, depends on the width of the side passage (1.20m). The benches located near the entrance and near the high altar are fixed. Service cables, including heating pipes, run in the “cocciopesto” floor. In order to open the large void in the floor, the transversal UB beams (IPE) had to be cut and three oblique steel posts had to be introduced (two posts under one of the long sides of the void and another post under the opposite side to avoid the archaeological finds); these posts, together with the reinforced concrete sidewalls, can be considered simple supports of the floor structure and are necessary to compensate for the structural discontinuity caused by the cutting of the pre-existing beams. Dead and live loads of the new glass walkaway act as forces and couples concentrated in the ends of the cantilevers and as couples distributed on the steel beams of the pre-existing floor. 7 1-2014 studies studi 1-2014 This structural hypothesis implies the maximum normal stress in the three posts and the maximum bending stress in the longitudinal steel beams of the pre-existing structure, parallel to and set back from the edges of the rectangular void. 8 Rivista della Stazione Sperimentale del Vetro Author Ugo Carughi Soprintendenza per i Beni Architettonici e per il Paesaggio e per i Beni Artistici, Storici ed Etnoantropologici di Napoli e provincia, Naples studies studi Rivista della Stazione Sperimentale del Vetro A new hybrid solution for structural glass reinforced beams Michel Palumbo, Dominque Palumbo, Teresa Mazzucchelli Introduction Although the standard glass design strategy is redundancy, we pursue a safer way to ensure the robustness of transparent glass beam structures. To attain this goal: the glass beams are calculated according to the different loading conditions, humidity level and structural characteristics of the context to suit the safety and aesthetic needs of the final user. In Figure 1, we show an example of the high-strength and toughened glass beam described above. • the first design principle is to give up using the traditional all-tempered laminated-glass beams, because the high resistance due to the tempering process entails no post-peak resistance; • the second design criterion (largely adopted in the past) is to reinforce annealed glass sheets with high-strength reinforcing materials (according to a patented glass-toughening protocol). In this case, we lose the strength of tempered glass but we gain substantial post-peak resistance of the whole glass beam (should all the glass layers fracture, the reinforcing belt would interconnect all the macro glass shards and sustain the tensile load, whilst the fractured glass would continue to transmit compressive loads). [1] • the third guideline is to wisely combine thermally strengthened glass sheets with reinforced annealed glass layers. Since glass is being increasingly used as a structural load bearing element, the patented innovation we describe herewith meets the two most important demands concerning structural glass: to increase the load bearing capacity of glass beams in conjunction with a high post-peak mechanical behaviour. The main idea is to combine a reinforced glass beam core (to guarantee safety), based on annealed glass sheets, with the higher-strength resistance of fully tempered glass. The stacking sequence, the reinforcement and all the materials used to assemble Figure 1. Underneath view of a hybrid glass beam. Both the steel reinforcing belt (glued to annealed glass layers) and glass load-bearing sheets can be seen 9 1-2014 studies studi 1-2014 Rivista della Stazione Sperimentale del Vetro Results and discussion The beams underwent preliminary four-point bending testing to simulate consistent load conditions. The tested beam dimensions are reported in Figure 2. Figure 2. Hybrid glass beam dimensions Figure 3. Hybrid glass beam test setup 10 studies studi The force-displacement plot of the four-point bending test is reported in Figure 4. All the glass layers bear the external loads in standard conditions. As the load increases, the inner glass panes start to crack in the middle and act as a warning signal. As the load increases, the reinforcing plate comes into play by redistributing the external pressure over the sides of the cracks, as described below in detail [1] (Figure 5). New cracks appear far from the beam midspan. The beam system is still able to withstand the loads because of the reinforcing belt and the presence of tempered glass sheets. Rivista della Stazione Sperimentale del Vetro Once the outer glass pane breaks, the hybrid glass beam system (steel-reinforced glass beam and anchoring brackets) is still able to sustain external loads because of the presence of the toughened and reinforced core [1-3]. All the cracks shown in Figure 5 appear in the toughened annealed-glass core. The beam is still able to withstand loads until the outer tempered glass layers break. After that, the glass beam behaves as an annealed-glass reinforced beam and offers the post-peak resistance as described elsewhere, i.e. [1], [2], [3]. Figure 4. Force - displacement plot of the hybrid toughened, reinforced glass beam 11 1-2014 studies studi 1-2014 Rivista della Stazione Sperimentale del Vetro Figure 5. Cracks progression based on the strain of the core toughened by means of high-strength strips Conclusions Glass is and will remain one of the most important materials in architecture. The results reported in this paper show the possibilities of adding extra value to glass if used in special structures. The brittleness of the material not only requires sophisticated global structural analyses (managed by the latest software tools) but also creates new challenges with regard to the detailing and assembly process. 12 Even if glass sizing is the first step to take when glass is used as a load bearing material, we must remember that many parameters affect the strength and the safety of a glass beam, i.e. stress corrosion, moisture, local defects or scratches, stress concentration, finishing of the loaded edges [4] and … load transfer between glass and context. studies studi Rivista della Stazione Sperimentale del Vetro Anchoring brackets design is a fundamental step of the glass design process, since they transfer the external loads from the glass beam to the outer structure. It is of the utmost importance to avoid stress concentration on the glass inside the brackets, since low global stress may locally increase to unacceptable values for glass. Thus the design of a reinforced, toughened glass beam can not ignore the design of the glass layup, the reinforcing strip, the redistribution of the external loads and the supports of the whole glass system. References 1. M. Palumbo and al., Structural glass beams supporting a new transparent roof, XXV A.T.I.V. Conference Parma (Italy) November 18-19, 2010; 2. Glass Processing Days - 16-21/06/2005 Tampere - Finland; 3. Tesi di Laurea Università di Brescia (Italy) “Vetro per gli impieghi strutturali” - 2006 U. Balestrieri e L. Bartoli; 4. Haldimann, M and Luible, A and Overend, M (2008), Structural use of glass. Iabse. Authors Michel Palumbo, Dominque Palumbo, Teresa Mazzucchelli Vetrostrutturale srl - Viale Venezia 220 25123 Brescia [email protected] 13 1-2014
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