Tobias Huber

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Huber

First Name

Tobias

ORCID

0000-0001-9248-1662

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Publications1 - 5 of 5

Digitally fabricated ribbed concrete floor slabs: a sustainable solution for construction
Mata Falcón, Jaime; Bischof, Patrick; Huber, Tobias; et al. (2022)
RILEM Technical Letters
The concrete used in floor slabs accounts for large greenhouse gas emissions in building construction. Solid slabs, often used today, consume much more concrete than ribbed slabs built by pioneer structural engineers like Hennebique, Arcangeli and Nervi. The first part of this paper analyses the evolution of slab systems over the last century and their carbon footprint, highlighting that ribbed slabs have been abandoned mainly for the sake of construction time and cost efficiency. However, highly material-efficient two-way ribbed slabs are essential to reduce the environmental impact of construction. Hence, the second part of this paper discusses how digital fabrication can help to tackle this challenge and presents four concrete floor systems built with digitally fabricated formwork. The digital fabrication technologies employed to produce these slab systems are digital cutting, binder-jetting, polymer extrusion and 3D concrete printing. The presented applications showcase a reduction in concrete use of approximately 50% compared to solid slabs. However, the digitally fabricated complex formworks produced were wasteful and/or labour-intensive. Further developments are required to make the digital processes sustainable and competitive by streamlining the production, using low carbon concrete mixes as well as reusing and recycling the formwork or structurally activating stay-in-place formwork.
Design, fabrication, and testing of an optimised reinforced concrete floor slab fabricated with robotically 3D printed formwork
Burger, Joris Jan; Huber, Tobias; Mata Falcón, Jaime; et al. (2022)
A prognostic neural epigenetic signature in high-grade glioma
Drexler, Richard; Khatri, Robin; Sauvigny, Thomas; et al. (2024)
Nature Medicine
Neural-tumor interactions drive glioma growth as evidenced in preclinical models, but clinical validation is limited. We present an epigenetically defined neural signature of glioblastoma that independently predicts patients' survival. We use reference signatures of neural cells to deconvolve tumor DNA and classify samples into low- or high-neural tumors. High-neural glioblastomas exhibit hypomethylated CpG sites and upregulation of genes associated with synaptic integration. Single-cell transcriptomic analysis reveals a high abundance of malignant stemcell-like cells in high-neural glioblastoma, primarily of the neural lineage. These cells are further classified as neural-progenitor-cell-like, astrocyte-like and oligodendrocyte-progenitor-like, alongside oligodendrocytes and excitatory neurons. In line with these findings, high-neural glioblastoma cells engender neuron-to-glioma synapse formation in vitro and in vivo and show an unfavorable survival after xenografting. In patients, a high-neural signature is associated with decreased overall and progression-free survival. High-neural tumors also exhibit increased functional connectivity in magnetencephalography and resting-state magnet resonance imaging and can be detected via DNA analytes and brain-derived neurotrophic factor in patients' plasma. The prognostic importance of the neural signature was further validated in patients diagnosed with diffuse midline glioma. Our study presents an epigenetically defined malignant neural signature in high-grade gliomas that is prognostically relevant. High-neural gliomas likely require a maximized surgical resection approach for improved outcomes.
Structural design and testing of material optimized ribbed RC slabs with 3D printed formwork
Huber, Tobias; Burger, Joris Jan; Mata Falcón, Jaime; et al. (2023)
Structural Concrete
Most of the concrete volume in multi-storey buildings is cast in solid slabs, which are frequently flat slabs supported on columns. By using two-way spanning ribbed slabs, concrete consumption could be significantly reduced. However, due to the high costs associated with formwork, such a complex rib configuration is rarely used nowadays. With the advent of technologies for automated formwork fabrication, the material-saving potential inherent in this structural system could again be exploited. This paper investigates the feasibility of material-efficient ribbed concrete slabs on a building scale using conventional concrete and steel reinforcing bars cast inside a 3D-printed plastic-based formwork. To that end, the code-compliant design of ribbed slabs is first discussed, followed by the introduction of a concept for an automated design-to-production workflow. The sustainability of this slab system is compared to a solution using conventional formwork in a case study consisting of a multi-bay office building with slabs spanning 8 m in both directions, revealing that ribbed slabs use 40% less concrete than solid slabs. Several representative structural elements of the case study (ribs, slab-column transition) were produced at full-scale and tested until failure to investigate the feasibility of production and structural performance. Three T-beams with various rib shapes (straight, kinked with diaphragms, curved) were tested in a three-point bending configuration, showing a ductile behaviour with longitudinal reinforcement yielding and indicating the relevance of torsional effects in curved ribs. Punching tests on two slab-column connections (ribbed, solid) revealed that the optimised ribbed slab could prevent brittle punching failures and achieve an ultimate load 105% higher than the solid reference slab. All specimens’ load-bearing behaviour could be predicted using established design formulas, showing the feasibility of producing code-compliant ribbed slabs with the applied technology.
Design and fabrication of optimised ribbed concrete floor slabs using large scale 3D printed formwork
Burger, Joris Jan; Huber, Tobias; Lloret-Fritschi, Ena; et al. (2022)
Automation in Construction
This paper describes the design, fabrication, and testing process of an optimised, reinforced concrete ribbed floor slab fabricated using robotically 3D printed formwork. The design of the floor slab is based on the alignment of ribs along the trajectories of the principal bending moments. A workflow is described that generates a rib layout based on structural analysis, which is used to create a three-dimensional model of the slab. A full-scale prototype is fabricated by using an industrial robotic arm with a pellet extruder mounted as an end effector to 3D print the formwork. Reinforcement is inserted and the formwork is cast using self-compacting concrete. The successful design, fabrication, and structural testing of the full-scale floor slab prototype showed that the described workflow is suitable for realizing material-optimised, ribbed reinforced concrete floor slabs using 3D printed formwork.

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Tobias Huber

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