Innovation in concrete structures using Digital Fabrication | Discussion & Questions

This is the replay of an e-Seminar organised by the fib Young Members Group Italy and the fib Task Group 2.11 "Structures made by digital fabrication".

Digital fabrication processes for fabricating concrete-like products, objects and/or structures are typically grouped into three main categories: (i) Layered Extrusion (e.g. contour crafting, concrete printing etc.), (ii) Binder Jetting (e.g. D-shape), (iii) Slip-forming (e.g. smart dynamic casting). However, to date, many important developments have been accomplished for layered extrusion technology, consisting of a digitally controlled moving printing head (or nozzle) that precisely lays down the concrete or mortar material layer-by-layer.

It is clear that the full understanding of the structural performances of digitally fabricated elements represents noteworthy progress in supporting the design of such innovative structures. In this way, reliable structural concepts and assessment methodologies could be integrated within existing international building codes/standards and adapted to the particularities of DFC, providing effective recommendations to the construction industry stakeholders.

The primary objective of the task group is to identify limiting aspects of the current design practice for the implementation of novel, digitally-fabricated concrete structures. Based on that, the task group will address fundamental structural issues related to the particularities of DFC with the final aim of providing effective guidelines for code-compliant applications.

0:00 Introduction | Marta Del Zoppo
0:43 fib | David Fernandez-Ordoñez
3:40 David Fernandez-Ordoñez | Marta Del Zoppo
4:32 Roundtable discussion | Marta Del Zoppo | Costantino Menna | Jaime Mata-Falcon | David Wang | Liberato Ferrara | Jacques Kruger | Freek Bos
5:00 Questions | Costantino Menna
5:58 What do you think triggers the deformation in "elastic buckling" case? The viscous deformation or low elastic properties?
9:30 Is poison ratio of 0.3 reasonable for fresh concrete?
11:30 Why did you consider more than 1 hour to reach the best process?
13:10 what kind of failure was in beams with textile reinforcing? normal/shear crack in stress zone/failure of reinforcing/stratification of concrete from reinforced mesh/other?
14:30 Would you have a way to place the reinforcement automatically or are you using a manual way ?
15:35 What values of partial safety factors should be used in design?
23:55 Was the aspect ratio of fibre adapted to the low bond strength at early age? What about fibre hybridisation?
25:35 What is/are the most reliable ways to validate topology optimisation geometry? What would be the ideal software to do structural validation?
27:10 Environmental impact: another challenge raised by Jaime saying that the cement content/use (CO2) is higher than conventional casting methods because the special concrete admixtures necessary for printing methods. This seems another factor not really helping the diffusion of this technology in a future which needs environmentally friend technologies. True is the fact the by printing we reduce waste and we can optimise the geometries/volumes but ......
31:14 As 3DCP, the main influencing parameter is workability, and ecological characteristics. As such is there any work going on developing "limit state of workability" standards in BS, EN, DIN, ACI, or FIB?
36:35 I am intrigued to ask about the printing process of concrete in outdoor situation (as shown in some projects that you showed in the presentation). Does the environmental and weather conditions (including temperature humidity…, etc.) significantly affect the properties of the printed concrete?
39:30 What's the best way that you find more realistic and industrially viable to be successful in a decent period of time?
44:25 Closure | Costantino Menna
46:30 Outro | Ganterbrücke/Ganter Bridge (Switzerland)

A bridge between research and practice.

The fib, Fédération internationale du béton, is a not-for-profit association formed by 42 national member groups and approximately 1000 corporate and individual members. The fib’s mission is to develop at an international level the study of scientific and practical matters capable of advancing the technical, economic, aesthetic and environmental performance of concrete construction.

The knowledge developed and shared by the fib (fib Bulletins, fib events, fib workshops, fib courses, etc.) is entirely the result of the volunteer work provided by the fib members.

The fib was formed in 1998 by the merger of the Euro-International Committee for Concrete (the CEB) and the International Federation for Pre-stressing (the FIP). These predecessor organizations existed independently since 1953 and 1952, respectively.

fib official website: https://www.fib-international.org/
fib YMG Italy: http://fibitaliayoung.it/
fib Task Group 2.11: https://www.fib-international.org/com...

Postproduction: Marie Reymond (fib Secretariat)