PSI - Issue 64

Saim Raza et al. / Procedia Structural Integrity 64 (2024) 1200–1207 Raza / Structural Integrity Procedia 00 (2024) 000 – 000

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6. Conclusion and Future Outlook This paper has presented the feasibility assessment of a novel prefabrication concept for ribbed slabs where post tensioned 3DPC is proposed to be used as lightweight stay-in-place formwork. The results of the study showed that from a design point of view, post-tensioned 3DPC formworks with a thickness of 30 mm and a ribbed topology could be feasible for span lengths of 4 to 6m. The study also evaluated the printing feasibility of such thin 3DPC formworks by printing to a height of 2m. In addition, the study offers some discussion and analysis on design implications of the corrugated surface of 3DPC compared to the flat surface of traditional concrete. The results show that the cracking load in prisms, where a corrugation with a sharp tip represents the 3D printed architecture, can drop by half compared to a corrugation-free prism. The reliability of this cracking load, however, lies in a thorough understanding of the singular region surrounding the representative corrugation. The proposed prefabrication concept is expected to offer several advantages over conventional fabrication techniques for ribbed slabs. The advantages include the fabrication of customized ribbed slabs with optimized geometries for long-span lengths and, the elimination of the need for temporary formwork and temporary shoring required in traditional construction, resulting in a significant reduction of construction cost and time. The next steps in this ongoing project include the experimental assessment of the moment capacity and failure modes of the proposed post-tensioned slender 3DPC formwork. In addition, topology optimization of the formwork along its span length will be performed for material efficient design. Acknowledgements The financial support from the Swiss Innovation Agency (grant no. 57896.1 IP - ENG) is gratefully acknowledged. The support of the lab staff and technicians of Structural Engineering Research Laboratory at Empa during the printing process and experimental testing is also acknowledged. The authors are also thankful to the Industrial partner BBR VT International AG for providing the materials and technical support for this project. References Bärnkopf, E., Kövesdi, B., Dunai, L. (2023). Investigation of Stress Concentration Zones in FEM-Based Design of Welded Plated Structures. MDPI Buildings, 13, 1057. Dell'Endice, A., Bouten, S., Van Mele, T., & Block, P. (2023). Structural design and engineering of Striatus, an unreinforced 3D-concrete-printed masonry arch bridge. Engineering Struc-tures, 292, 116534. doi:https://doi.org/10.1016/j.engstruct.2023.116534 Jha, K.N. (2012), Formwork for Concrete Structures, Tata McGraw Hill Education Private Limited, New Delhi, ISBN (13): 978-1-25-900733-0. Mata-Falcón, J., Bischof, P., Huber, T., Anton, A., Burger, J., Ranaudo, F., . . . Kaufmann, W. (2022). Digitally fabricated ribbed concrete floor slabs: a sustainable solution for construction. RILEM Technical Letters, 7, 68-78. doi:10.21809/rilemtechlett.2022.161 Raza, S., Triantafyllidis, Z., Anton, A., Dillenburger, B., Shahverdi, M., 2024. Seismic performance of Fe-SMA prestressed segmental bridge columns with 3D printed permanent concrete formwork. Engineering Structures 302: 117423. Sakha, M. (2023). FRACTURE INITIATION AND PROPAGATION IN ANISOTROPIC ROCKS, ETH Zurich, Switzerland. https://doi.org/10.3929/ethz-b-000651168 Simulia. (2006). ABAQUS Analysis User's Manual: Solid (continuum) elements (Section 22.1.1). Version 6.6 Documentation. Zhang, P., Xu, F., Liu, Y., & Ahmed Sheikh, S. (2022). Shear behaviour of composite beams with permanent UHPC formwork and high-strength steel rebar. Construction and Building Materials, 352, 128951. Zhu, B., Nematollahi, B., Pan, J., Zhang, Y., Zhou, Z., & Zhang, Y. (2021). 3D concrete printing of permanent formwork for concrete column construction. Cement and Concrete Composites, 121, 104039. doi:https://doi.org/10.1016/j.cemconcomp.2021.104039 Prihar, A., E.M. Garlock, M., Najmeddine, A., and Moini, R. (2024). Mechanical performance of sinusoidally architected concrete enabled by robotic additive manufacturing. Materials & Design, 238, 112671.