Fi. 1: Carrier frame fabrication concept.
Gustav FaGerström, Buro H appold, erik verBoon, Buro Happold, roBert aisH
uni ver sity oF BatH
Computational desin tools based on Autodesk’s DesinScript lanuae have been used with eometry and topoloy modellin
techniques in the desin of a climatised free-form buildin envelope. This project involves structural and performance analysis tools
applied to structural enineerin, façade enineerin and fabrication plannin. The project has proressed from concept throuh
tender phases. The particular eometry presented unique conditions that required non-standard solutions to be used; to this end
DesinScript was introduced to allow the desin and enineerin team to build a number of scripted topoloical façade models that
explored alternative façade confiurations. This paper combines a discussion about the specific fabrication project with a more
eneralised discussion of the role of computational tools in desin and fabrication. The main interest is to explore the two-way
relationship between practice and tool buildin by considerin how computation can contribute to a practical fabrication project and
equally important, how computational tools can be tested and refined by bein used in practice on demandin projects.
The architectural concept used in this paper is based on a
sculptural approach in which lass joints alternate between
uniquely anled concave and convex relationships between
adjacent panels (fi. 2).
The self-weiht of the lare insulated lass units (IGU) de-
mands a support stratey where the ede of each panel should
be continuously supported. This requires that a strict eomet-
ric relationship be maintained between the lass and the sup-
port structure. Furthermore, the eometric conditions around
each node are unique, bein the simultaneous meetin point
for both concave and convex lass panels. Consequently, each
node, while based on a common topoloical principle, has a
unique eometric confiuration, and therefore requires the
development of a unique fabrication eometry.
As a base constraint, the architect had instructed that a
point-supported approach was undesirable and expressed a
preference for the use of rectanular or plate primary struc-
tural elements as opposed to the more traditional round hol-
low section and spherical node approach often found in struc-
tures of this type. The subsequent studies looked at both
structural approaches as a system that was offset from the Fi.2: Site Context. (Imae courtesy of Robert A. M. Stern Architects)
lazin line. The method for supportin the lass to the pri-
mary structure utilised continuous anles, or ‘carrier frames’
that followed and were structurally attached to the lass ed-
es via structural silicone sealant. Periodic steel plates struc-
turally linked the lass to the primary structure, while also ad-
dressin the chanin distance and anle between the two
systems. The multiple anled relationships between lass pan-
els required that the IGU’s have steppin or cantilevered inner
or outer lihts in order to maintain a consistent external joint
DesinScript (as the interation of lanuae, eometry, topol-
oy and plu-ins) allowed the enineerin team to assess the
eometric feasibility of the architectural concept by buildin a
number of alteratively scripted topoloical façade models. This
approach enables the team to model the correspondence be-
tween the façade topoloy and the physical components of the
facade: lass panels as topoloical faces, structural members
as topoloical edes and node connectors as topoloical verti-
ces. DesinScript topoloy classes reveal the underlyin func-
tionality of the Autodesk Shape Manaers (ASM) via its API ¹
The sinle topoloical mesh model allows each of the con-
stituent components (face, ede or vertex) to make topoloi-
cal and eometric queries to the adjacent components, for ex-
ample, the computation of averae vertex normals, and ede
bisectors. Additionally, DesinScript is interated with Robot
Structural analysis and Performative Desin and reveals us-
er-oriented API’s directly to the enineers usin DesinScript.
This allows the sinle topoloical mesh model to be direct-
ly analysed both structurally and environmentally, while the
mesh also forms the basis for related fabrication models.
application: ca se study
Typically, facades are modelled as meshes usin the architect-
established desin surfaces (here represented by the front of
lass (FOG). The structural support system is typically defined
as an offset mesh from this definin mesh. The resultin struc-
ture is more easily realised if the definin mesh has ‘torsion-
free’ nodes. This means that the vertex normals at the end of
each ede are coplanar and the ede members are planar.
In some cases, a mesh with non-torsion-free nodes can be
optimised by movin the vertex positions ² (Wallner and Pott-
mann, 2011). This approach is more appropriate where the
mesh represents a smooth surface and the chanes in vertex
position (and hence the shape of the façade panels) is not visu-
ally apparent. However, the desin intention for this façade is
to create a very specific faceted confiuration, which could not
be optimised in this way.
In a non-torsion-free facade, the ede normal (as the bi-
sector of the ede’s adjacent faces) and the vertex normals at
either end of the ede are not coplanar. If the ede members
are planar and based on their respective ede normal, then
the ede members meetin at a common vertex will not in-
tersect alon a common vector (fi. 3). Alternatively, if it is re-
quired that all ede members intersect at a common vector at
each vertex, then the structural system has to resolve the twist
alon the ede members.
A carrier frame and offset structure was considered. If the off-
set structure is based on a uniform offset from the face of the
definin façade, then the edes of the offset may not lay on the
face bisectors, and the relationship between the carrier frame
and the offset structure may have to be desined to accommo-
date such deviations.
While these 2D studies were conceptually useful, a 3D ap-
proach was necessary to address the multiple unique condi-
tions imposed by the eometry. Buildin on this exploratory
work, a scripted approach was developed, harnessin mesh to-
poloy and allowin for the automated creation of panels from
mesh faces, structural members from mesh edes and connec-
tor nodes from mesh vertices (fi. 4).
N0 - Average normal
B - Bisectors
N - Normals
Fi. 3: Characteristics of non-torsion-free eometry,
averae node vertex normal principle and ede face bisectors.
Fi. 4: Desin eometry expressed as topoloy mesh.
Fi. 5: The mesh topoloy used to define the façade.
Orane lines: the edes of the primary façade mesh
(front of lass)
Red lines: the averae vertex normals
Cyan lines: the weihted averae vertex normals
(weihed by the face areas)
Maenta lines: the offset mesh (used to define
the offset structure) (based on offsettin the vertices
of the primary mesh alon the weihted averae
The ede-based structural system has to support one or two
planar sheets of lass and the twist between the vertices at
its ends. The question remains: Should there be a sinle ede
member that combines all these roles or a carrier frame to sup-
port the planar lass linked to a separate structural member to
accommodate the twist?
Four structural hypotheses were considered:
Carrier Frame and Plate oriented alon the ede normal (fi. 6)
– Carrier Frame and Plate twistin to accommodate both end
points’ vertex normals (fi. 7)
– Chamfered tube with chamfer axis usin the averae vertex
normal (fi. 8)
– Offset structure and carrier frame, with offset node con-
nectors based on the averae vertex normal (fis. 9– 10)
Fi. 6: Structural Hypothesis 1 – Carrier frame and plate, with the plate
oriented alon ede normal.
Fi. 7: Structural Hypothesis 2 – Carrier frame and Plate, with the plate
twisted between end points’ non co-planar vertex normals.
Fi. 8: Structural Hypothesis 3 – Chamfered tube with chamfer axis usin
the averae vertex normal
Fi. 9: Structural Hypothesis 4 – Offset structure and carrier frame,
with the offset node connectors based on the averae vertex normal.
The different test models were built on a simple hand-coded
test mesh (fis. 5–8). DesinScript allowed the test mesh to be
swapped out for the full mesh in order to build the complete
facade (f is. 9–10).
Fis. 10–12: Desin development model with offset structure
and carrier frame fabrication concept.
DesinScript provides a familiar ‘data flow’ approach to desin
computation and makes the creation and execution of desin
loic accessible to desiners with little or no prorammin ex-
perience. In this project, data from the input nodes in the top
left part of the raph ‘flows’ via intermediate mesh modelin
nodes to create the facade in the bottom riht part of the raph
(f i. 1 4).
The ‘data flow’ approach works well with simple models.
However, usability issues bein to emere when the problem
bein addressed ets more complex and there are many more
nodes to consider. This issue is addressed throuh the ‘node to
code’ functionality in DesinScript which automatically trans-
lates the user’s data flow diaram into an associative script
(fi. 12). DesinScript also includes support for reular impera-
tive scriptin usin conventional ‘for’ loops (for iteration) and
‘if’ statements (for conditionals) ³ (Aish 2013).
Bracketlength Carrierangle Position
7.204577 112 A11‐1
9.277795 114 A11‐2
8.996179 140 A11‐3
8.973133 52 B7‐1
6.642246 83 B7‐2
8.632262 22 B7‐3
6.056679 85 B2‐1
6.814823 154 B2‐2
7.22186 40 B2‐3
8.648544 131 A9‐1
8.918658 71 A9‐2
6.064782 47 A9‐3
6.664838 152 A8‐1
7.675841 37 A8‐2
6.426951 102 A8‐3
9.645642 48 T2‐1
6.832239 26 T2‐2
7.152264 133 T2‐3
7.25188 126 T9‐1
7.055309 43 T9‐2
6.64823 27 T9‐3
7.916496 46 T2‐1
8.305637 40 T2‐2
9.694806 18 T2‐3
8.837067 52 C5‐1
6.535089 78 C5‐2
6.896258 133 C5‐3
8.967901 42 D5‐1
7.42581 114 D5‐2
8.955504 141 D5‐3
Fi. 14: Diaram outlinin DesinScript data flow raph used as a visual prorammin interface (top)
as well as its ‘node to code’ functionality (bottom) allowin the desiner to selectively replace all
or part of a raph node diaram with the correspondin code, thus makin it possible to reduce visual
clutter and proress to a more succinct form of desin computation.
Fi. 13: umerical output complementin or replacin
traditional shop drawins.
Movin forward into fabrication plannin with hypothesis4
(above), the process was reversed with respect to that out-
lined in fi. 4. The topoloically represented structure is now
the source of an additional level of information describin the
carrier brackets’ lenth, shape, anle and position within the
overall assembly. The resultin information packae (fi. 13)
can be used in conjunction with – or entirely in lieu of – tradi-
tional shop drawins.
This project demonstrates that script-driven topoloy can be
used as the central representation for eometric assessment,
structural analysis, performative analysis, fabrication plan-
nin and component enineerin, ultimately providin an ef-
fective way to realise a challenin façade.
More enerally, it is reconised that computation is drivin
more aspects of contemporary architectural and enineerin
practice. The contribution of DesinScript is to unify compu-
tation, eometry and topoloy with alternative prorammin
interfaces (both visual and textual) and thereby support differ-
ent levels of computational skill.
It is important to reflect on the results of this work. At one
level, it is the physical buildin. At another level, it is the op-
portunity this project provided to test and refine a new en-
eration of computational desin tools. But maybe the most im-
portant result is the acquisition of knowlede and skills made
by the practitioners. All three results have the potential to con-
tribute to even more challenin projects.
DesinScript Development Team, Autodesk Sinapore Research
Andrew Marsh for the Performative Desin plu-in for DesinScript
Al Fisher and Buro Happold Bath for the Autodesk Robot Structural
Analysis plu-in for DesinScript
Buro Happold ew York Structures and Facades roups
Robert A.M. Stern Architects
DesinScript is available at Autodesk Labs, http://labs.autodesk.com/
Additional information and plu-ins for DesinScript are available at
1 Robert Aish and Aparajit Pratap, ‘Spatial Information Modelin of
Buildins usin on-Manifold Topoloy with ASM and DesinScript’,
in Proceedings of Advances in Architectural Geometry (Paris:
Spriner 2012), pp. 25–36.
2 Johannes Wallner and Helmut Pottman, ‘Geometric Computin
for Freeform Architecture’, Journal of Mathematics in Industry 1,
no. 4 (2011).
3 Robert Aish, ‘DesinScript: A Learnin Enviroment for Desin
Computation’, in Proceedings of the Design Modelling Symposium
(Berlin: Spriner, 2013).