Striatus: Strength through Geometry

Striatus is an arched, unreinforced masonry footbridge composed of 3D-printed concrete blocks assembled without mortar. The 16×12-metre footbridge is the first of its kind, combining traditional techniques of master builders with advanced computational design, engineering and robotic manufacturing technologies.

The name “Striatus” reflects its structural logic and fabrication process. Concrete is printed in layers orthogonal to the main structural forces to create a “striated” compression-only funicular structure that requires no reinforcement.

Exhibited at the Giardini della Marinaressa in Venice, the footbridge offers an alternative path for visitors who can engage with the structure by crossing the bridge or walk underneath its central arch.

Stratius – 3D printed Bridge at Giardini della Marinaressa, Venice, Italy. Photo Credit: @studio_naaro

Striatus is an unreinforced concrete structure that achieves strength through geometry, rather than an inefficient accumulation of materials as in conventional concrete beams and flat floor slabs. Concrete can be considered as an artificial stone that performs best in compression. In arched and vaulted structures, material is placed precisely so that forces can travel to the supports in pure compression, which can significantly reduce the amount of material needed to span space as well as the possibility to build with lower-strength, less-polluting alternatives.

Stratius – 3D printed Bridge at Giardini della Marinaressa, Venice, Italy. Photo Credit: @studio_naaro

A new language for Reusable concrete 

Striatus highlights the congeniality between masonry structures, 3D concrete printing and contemporary design; it strives for a new language for concrete. It seeks an alternative to ‘beton brut’, the raw concrete that dominated 20th-century architecture. Instead, Striatus is a ‘beton nouveau’, a structurally informed, fabrication-aware, ecologically responsible, precisely placed and articulate alternative to the traditional ways of building.

The 9-metre-span prototype blends the construction principles of the master builders of the past with novel computational design, engineering and robotic manufacturing. Its name reflects its structural logic: Striatus uses concrete in a layered fabrication process to create a compression-only structure that eliminates material waste. The absence of binder or glue makes it endlessly reusable: it can be easily disassembled and reassembled elsewhere.

Stratius Drawings- 3D printed Bridge at Giardini della Marinaressa, Venice, Italy. Credit: @blockresearchgroup and @zhcode

Masonry-informed 3D concrete printing

The blocks of the masonry structure are fabricated using robotic 3D concrete printing, an extrusion-based, additive manufacturing process in which concrete material is deposited layer by layer, with each layer typically horizontal but in this case the layers are inclined. A novel design approach, this capability aligns both the printed blocks and the material layers within the blocks to be orthogonal to the expected compressive force flow. This unique fabrication process also enables intricate cross-sectional design, unifying aesthetic, structural, and assembly requirements, resulting in materially-reduced sections and articulate, functional features that would be hard to achieve in conventional, multi-material assemblies.

3D molding and construction. Photo Credits: @incremental3d.eu

During the inauguration of Stratius at Giardini della Marinaressa on the 15th of July 2021, Philippe Block explained about the novelty of this project and its value by saying: “We really want to startle the profession by actually showing quite a few things, quite a few layers to this project. What we are trying to do here is to try to demonstrate that perhaps we have forgotten some essential knowledge in the past.

Philippe continues his inauguration speech by saying: “we translate these historical principles of the vaults of cathedrals and so on to reintroduce them in modern day practice. And so, we wanted to challenge and to design, not just have a simple, silly arch, but we have a spatial arch to show that actually, through computation and things like that, we can extend these exciting geometries indeed.

Stratius Drawings – Credit: @blockresearchgroup and @zhcode

Proposing a new language for concrete that is structurally informed, fabrication aware, ecologically responsible and precisely placed to build more with less, Striatus optimises the interrelated properties of masonry structures, 3D concrete printing (3DCP) and contemporary design; presenting an alternative to traditional concrete construction.

Philippe adds by saying that: “I think the constraint is that we have only one planet, and so that we have to basically build significantly more responsible. We believe as a team that if we want to have impact.” This is also a statement about how to design for full reuse and disassembly at the end of the life.

What’s exciting about this is that these elements have, with almost no energy, can be just shredded, recycled, and they become the material stuck for the next bunch of elements.

As a part of the ‘Time Space Existence’ exhibition by @ecc_italy at the Giardini della Marinaressa until November 2021, Striatus has been developed by the @BlockResearchGroup (BRG) at @ETHZurich and Computation & Design group (@ZHCODE) at @zahahadidarchitects, in collaboration with @incremental3d.eu and made possible by @holcim.ltd.

Prior to the inauguration of Statrius, ECC Team had the privilege of interviewing Alessandro dell’Endice and Tom Van Mele. You can watch this interview on the IGTV of ECC Italy and find more information about Stratius Bridge on their dedicated website.

Construction of Stratius at Giardini della Marinaressa, Venice, Italy Photo Credits: Alessandro dell’Endice & Tom Van Mele

Construction of Stratius at Giardini della Marinaressa, Venice, Italy Photo Credits: Alessandro dell’Endice & Tom Van Mele

Stratius – 3D printed Bridge at Giardini della Marinaressa, Venice, Italy. Photo Credit: @studio_naaro

Striatus: Strength through Geometry

Striatus is an arched, unreinforced masonry footbridge composed of 3D-printed concrete blocks assembled without mortar. The 16×12-metre footbridge is the first of its kind, combining traditional techniques of master builders with advanced computational design, engineering and robotic manufacturing technologies.

  • Published: 20.07.2021
  • Category: In Focus
  • Subject: Participants
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