Rebecca Ammann
Rebecca Ammann
Student / Programme Doctorate at D-BAUG
ETH Zürich
Additional information
Position:
- Research Assistant, Chair of Concrete Structures and Bridge Design, Institute of Structural Engineering, Swiss Federal Institute of Technology (ETH) Zurich
- Doctoral student at the Swiss National Centre of Competence in Research (NCCR) Digital Fabrication
Education:
- MSc ETH in Civil Engineering at ETH Zurich, Major in Structural Engineering and Geotechnical Engineering
Professional Experience:
- since 2022: Research Assistant at ETH Zurich
- 2019 – 2022: Project engineer in Structural Engineering at dsp Ingenieure + Planer AG, Uster
- 2016 - 2017: Internship in Structural Engineering at Dr. Lüchinger + Meyer Bauingenieure AG, Zurich.
Honours
Year | Distinction |
---|---|
2019 | Willi-Studer-Preis |
Publications
- Enhancing structural efficiency with digital concrete – Principles, opportunities and case studiesLukas Gebhard, Jaime Mata Falcón, Rebecca Ammann, Nadine Preßmair, Benjamin Kromoser, Costantino Menna, Abtin Baghdadi, Harald Kloft, Michael Gabriel, Martin Walch and Walter KaufmannCement and Concrete Research, vol. 185, pp. 107645, Elsevier, 2024.
This paper explores the opportunities of digital fabrication with concrete (DFC) to improve structural efficiency and achieve sustainable construction. Efficient structural solutions that drastically reduce material consumption can be achieved by ensuring direct load flow and placing material where needed. More than 50 % of material savings can be achieved by using flanges or hollow sections, providing continuity in beams or slabs, reducing the span of structures or using structural systems such as arches, trusses or deep beams. These concepts are not fully exploited as they often require expensive and complex formwork. DFC tackles the latter point, as it promises to produce complex geometries, minimising extra effort, cost, or waste. The paper discusses the optimisation potential of DFC for several structural elements and presents existing applications that demonstrate this potential. Five case studies of different technological approaches are discussed in detail, highlighting advantages and disadvantages to be addressed for widespread adoption.
- Environmental benefits of concrete floor slabs produced with digitally fabricated formworks – a case studyRebecca Ammann, Lukas Gebhard, Karel Thoma, Jaime Mata Falcón and Walter KaufmannDigital Concrete 2024. 4th RILEM International Conference on Concrete and Digital Fabrication, Munich, Germany Braunschweig: Technische Universität Braunschweig, September 4-6, 2024.
- Digitally fabricated weak interfaces to reduce minimum reinforcement in concrete structuresPatrick Bischof, Jaime Mata Falcón, Rebecca Ammann, Andreas Näsbom and Walter KaufmannStructural Concrete, vol. 24: no. 2, pp. 1835-1855, Lausanne: International Federation for Structural Concrete, 2022.
Crack initiators in reinforced concrete structures can facilitate fulfilling the serviceability requirements. They can be used as a design parameter to diminish the minimum reinforcement for members subject to imposed deformation and exposed to the environment as they reduce the crack spacing and width when arranged close enough. While crack initiators in conventional concrete construction are cumbersome to provide (e.g., by construction joints or taperings), they are inherent to layered extrusion processes with digital fabrication technologies: the tensile strength is typically reduced locally in interfaces between layers. Rather than trying to avoid these weak interfaces, this paper discusses the potential of taking advantage of them to act as crack initiators reducing the minimum reinforcement content. A tension chord-based model is developed to (i) account for the local strength reduction and (ii) predict the effect of weak interfaces on the expected crack spacing and width. As a key finding, the model predicts a reduction of the required minimum reinforcement ratio proportional to the locally decreased concrete tensile strength for a specified maximum crack width requirement under imposed deformations. An experimental campaign on five layered and three reference tension ties confirmed the clearly positive impact of weak interfaces on crack spacings and widths.
- Layer-by-layer deposition on a heterogeneous surface: Effect of sorption kinetics on the growth of polyelectrolyte multilayersHervé Bellanger, Kirstin Casdorff, Livius F. Muff, Rebecca Ammann, Ingo Burgert and Benjamin MichenJournal of Colloid and Interface Science, vol. 500, pp. 133-141, Orlando, FL: Elsevier, 2017.
Surface functionalization by means of controlled deposition of charged polymers or nanoparticles using the layer-by-layer (LbL) approach has been used to modify mostly engineered materials with well-defined surface chemistry and morphology. In this regard, natural and inhomogeneous interfaces have gained very little attention. Furthermore, natural substrates are susceptible to alterations by factors commonly used to control the growth of multilayers, such as pH, temperature and ionic strength. Here, we study the impact of sorption kinetics of a bilayer system (Poly(diallyldimethylammonium chloride) (PDDA) and Poly(sodium 4-styrenesulfonate) (PSS)) on a natural heterogeneous wood surface at neutral pH, without salt addition, on the multilayer buildup. To overcome analytical limitations we introduce a complementary approach based on UV reflectance spectroscopy, atomic force microscopy (AFM) and zeta potential measurements. Compared to immersion times used for ideal substrates, we found that a high surface coverage requires relatively long immersion, approximately 30 min, into polyelectrolyte solutions, while a sufficient removal of polyelectrolyte excess during the washing step, requires even longer, about 100 min. Based on these findings, we show that film growth can be controlled kinetically. Long immersion times provide well-defined and regular multilayers. The obtained data points to specific requirements to be considered when LbL treatments are applied to rough, porous and heterogeneous surfaces, and thereby sets a basis for a successful transfer of various surface functionalization approaches already shown on ideal surfaces.