PSI - Issue 47

Domenico Ammendolea et al. / Procedia Structural Integrity 47 (2023) 488–502 Author name / Structural Integrity Procedia 00 (2019) 000–000

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5. Conclusions In this work, a novel numerical strategy has been proposed for the failure simulation of nano-filled Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) structures under general loading conditions. Such a strategy adopts a Moving Mesh approach used in synergy with an R -curve approach to capture the ductile behavior of such structures. According to the proposed FE-based modeling approach, both the crack onset condition and the crack advance criterion require the evaluation of Mixed-Mode fracture variables at the current crack tip, which is made possible by using an M -integral approach, newly formulated in the adopted moving mesh frame. As the main aspect of novelty of this work, an effective combined analytical/numerical procedure has been proposed to accurately determine R -curve functions starting from the available experimental data in terms of load displacement curves measured for laboratory-scale specimens (with or without pre-crack) subjected to general Mode-I fracture tests. This procedure has been fully validated via suitable comparisons with experimental outcomes found in the recent literature concerning the flexural response of UHPFRC beams enhanced with embedded nano-materials. The results have demonstrated that very good estimations of the fracture behavior can be achieved if the R -curve is calibrated via a rigorous curve fitting approach integrated within the proposed strategy. Moreover, a Mixed-Mode fracture test has been simulated by means of the proposed procedure, with the aim of investigating the capability of the adopted Moving Mesh technique to capture nonprescribed crack paths. The main advantage of the proposed numerical strategy is the possibility to perform complete failure analyses of nano-filled UHPFRCs under general loading conditions with minimal remeshing and, therefore, in a sensibly more efficient manner with respect to conventional fixed mesh-based approaches. As possible future perspectives of the present work, the proposed numerical methodology could be extended to the 3D setting as well as to multiple crack propagation problems, so that it could be also applied to the failure analysis of Reinforced Concrete (RC) structures and composite structures (Greco et al., 2012; Greco, 2013; Bruno et al., 2014; Pranno et al., 2022a; De Maio et al., 2023b), which usually experience diffuse cracking along complex Domenico Ammendolea gratefully acknowledges financial support from the “Programma Operativo Regionale (POR) Calabria FESR-FSE 2014/2020”. Lorenzo Leonetti, Paolo Lonetti and Rosa Penna gratefully acknowledge financial support from the Italian Ministry of University and Research (MUR) for the Research Grant “PRIN 2020 No. 2020EBLPLS” on “Opportunities and challenges of nanotechnology in advanced and green construction materials”. Arturo Pascuzzo gratefully acknowledges financial support from the Italian Ministry of University and Research (MUR) for the Research Grant “PRIN 2020 No. 2020EBLPLS” on “Opportunities and challenges of nanotechnology in advanced and green construction materials” and the “Programma Operativo Nazionale (PON) 2014-2020”, Azione IV.6 - Rep. N. 1062 of 10/08/2021. References Ammendolea, D., Greco, F., Leonetti, L., Lonetti, P., Pascuzzo, A., 2023. A Numerical Failure Analysis of Nano-Filled Ultra-High Performance Fiber-Reinforced Concrete Structures via a Moving Mesh Approach. Theoretical and Applied Fracture Mechanics 103877. https://doi.org/10.1016/j.tafmec.2023.103877 Ammendolea, D., Greco, F., Lonetti, P., Blasi, P.N., Pascuzzo, A., 2020. Crack growth propagation modeling based on moving mesh method and interaction integral approach. Procedia Structural Integrity, 1st Virtual European Conference on Fracture - VECF1 28, 1981–1991. https://doi.org/10.1016/j.prostr.2020.11.022 Ammendolea, D., Greco, F., Lonetti, P., Luciano, R., Pascuzzo, A., 2021. Crack propagation modeling in functionally graded materials using Moving Mesh technique and interaction integral approach. Composite Structures 269, 114005. https://doi.org/10.1016/j.compstruct.2021.114005 Bruno, D., Greco, F., Luciano, R., Nevone Blasi, P., 2014. Nonlinear homogenized properties of defected composite materials. Computers & Structures 134, 102–111. https://doi.org/10.1016/j.compstruc.2013.11.018 Chuah, S., Pan, Z., Sanjayan, J.G., Wang, C.M., Duan, W.H., 2014. Nano reinforced cement and concrete composites and new perspective from graphene oxide. Construction and Building Materials 73, 113–124. https://doi.org/10.1016/j.conbuildmat.2014.09.040 geometrical patterns. Acknowledgements