Page 20 - Designing Ways 247

3D PRINTING
blocks experience low stresses
throughout their use, resulting
in no loss of structural integrity.
Striatus separates components
in compression and tension,
ensuring external ties can be
easily accessed and maintained,
resulting in a longer lifespan for
the entire structure.
Recycle:
• By ensuring different materials glues or binders, ensuring a simple,
are separated and separable, each low-energy recycling process at the
component of Striatus can easily
be recycled with minimal energy after multiple cycles of reuse. design allows the resulting components
and cost. 3D printing also avoids
the waste and costs associated with
single-use moulds. Additionally, the
component materials within Striatus
remain separate and separable with
the use of mechanical connections
such as simple dry contacts between
the voussoirs rather than chemical
20 Issue 247 • dw
a 6-axis, multi-DOF robotic arm. This
new generation of 3D concrete printing
end of the elements’ life, potentially in combination with the arched masonry
to be used structurally without any
Robotic 3D concrete printing reinforcement or post-tensioning.
Unlike typical extrusion 3D printing To prevent misalignment between the
in simple horizontal layers, Striatus uses direction of structural forces and the
a two-component (2K) concrete ink orientation of material layers that arises
with corresponding printing head and from typical shape-agnostic slicing of
pumping arrangement to precisely print explicitly modelled geometry, a custom-
non-uniform and non-parallel layers via developed design pipeline was formulated
for Striatus to ensure that its printed layers
are wholly aligned with the direction of
compression forces throughout the entire
bridge, and also locally through each
3D-printed block. To address issues and
challenges that could prevent in-between
stability during printing, the coherence
and feasibility of the gradually evolving
print paths have been modelled using
a Functional Representation (FRep)
process.
This process encodes and continuously
checks rules of minimum overlap,
maximum cantilever between print layers
and print length, print speed and the
volume of wet concrete extruded. These
measures, typically used in horizontally
layered 3DCP, have been advanced and
refined to work on an inclined-plane
setting:
• The angular differences between
start and end planes of all 53 printed
blocks have been simultaneously
adjusted to meet multiple criteria
such as an appropriate structural
contact and angle between adjacent
blocks, and maximum print
inclination.
• The careful design and iterative
refinement of the hollow cross
sections and infill triangulation
have ensured that material is
placed corresponding to the
precisely analysed, local structural
performance of each block. This
design and optimisation has been