Questo articolo ha come oggetto il comportamento strutturale di travi in cemento armato (c.a.) con aggregati da riciclo provenienti da scorie di acciaieria.
Alcune travi in c.a. con scorie da acciaieria sono state testate con prove a flessione su quattro punti al fine di caratterizzarne il comportamento strutturale in termini di carico ultimo, deflessione e quadro fessurativo, da confrontare con quelli ottenuti in travi in c.a. con aggregati tradizionali.
Quindi, è stata condotta un’indagine numerica attraverso due procedure agli elementi finiti, la prima riguardante un’analisi incrementale step-by-step mediante il legame costitutivo non-lineare del calce-struzzo e un approccio a frattura diffusa, la seconda basata sull’analisi limite.
Si discute quindi il confronto tra dati numerici ed evidenze sperimentali, al fine di delineare aspetti salienti del comportamento strutturale di queste travi, e altresì evidenziare vantaggi e svantaggi delle due procedure numeriche adottate.
D. De Domenico1, F. Faleschini2, C. Pellegrino2, G. Ricciardi1
1 Department of Engineering, University of Messina, Italy
2 Department of Civil, Environmental and Architectural Engineering, University of Padua
The use of recycled materials as partial or full replacement of coarse natural aggregates in reinforced concrete (RC) members is particularly appealing because of the resulting economic and sustainability implications.
Of particular relevance to this research, encouraging results have been obtained quite recently by using electric arc furnace (EAF) slag as partial or total replacement of natural aggregates in the structural concrete mixes (Manso et al. 2004; Pelle-grino & Gaddo 2009; Pellegrino et al. 2013; Arribas et al. 2015; Rondi et al. 2016).
The EAF slag is a by-product of steel production in electric arc furnace plants. Considering the high amounts of EAF slag developed in countries like Italy and Spain (around the 30% of the overall European production), investigating alternative uses of these products avoiding their mere landfilling is an important research subject that deserves investigation.
To further encourage these investigations, previous studies have demonstrated that the use of EAF as coarse aggregates improves the mechanical properties of concrete, in terms of compressive and tensile strength, elastic properties (Faleschini et al. 2017c), and durability. These enhanced mechanical features are not only ob-served in small scale specimens, but also in applications involving real-scale structural elements like columns (Kim et al. 2013), beams (Pellegrino & Faleschini 2013) as well as beam-column joints (Faleschini et al. 2017a,b).
Along this research line, the present contribution aims to analyze, both from an experimental and nu-merical point of view, the structural behavior of 8 real-scale RC beams with EAF slag as full replacement of natural aggregates.
These beams exhibited either bending or shear failure, and were compared to four reference RC beams with natural aggregates.
The experimental results are then numerically simulated with two different finite element (FE) procedures (De Domenico et al. 2018).
The first method implies a conventional step-by-step incremental analysis based on a bilinear plasticity model for steel in conjunction with a nonlinear stress-strain law for concrete in compression and a post-failure response in tension based on a smeared-crack approach in order to capture fracture onset and development with increasing load.
The second method is an iterative, simplified methodology based on the application of the limit analysis theory, considering a plasticity model for concrete and steel. Despite the different underlying theoretical principles, the same failure surface is adopted for comparative purposes of the two procedures. Comparison between numerical and experimental results is discussed and the main ad-vantages and drawbacks of the two numerical procedures are outlined.
KEYWORDS: reinforced concrete; electric arc furnace (EAF) slag; recycled concrete; finite element modelling; limit analysis / calcestruzzo armato; scorie da acciaieria; calcestruzzo riciclato; modellazione ad elementi finiti; analisi limite
Articolo presentato in occasione degli Italian Concrete Days 2018 di aicap e CTE
Dal 14 aprile al 17 aprile 2021 si terrà la terza edizione degli Italian Concrete Days. Ulteriore informazione sull'evento a questo LINK.
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