SURFACE CONSTRUCTIBILITY
THE REPRESENTATION OF SURFACE CONSTRUCTIBILITY
Muhammad Farihan Irfan Mohd Nor, Azimin Samsul Mohd Tazilan, Abdul Halim Ismail,
Ismar Minang Satotoy Usman
¹Architecture Department,
Faculty of Engineering, Universiti Kebangsaan Malaysia,
43600 UKM Bangi, Selangor, Malaysia.
E-mail: [email protected]
Tel: 00603 8921 6844/6299 Fax: 00603 8921 6841 INTRODUCTION
It is important for us to identify the types of surface forms that form most of today’s
contemporary architecture, from the simplest form of building to the more complex
form of buildings like the Guggenheim Museum in Bilbao, Spain. In studying these
surface forms, the writer focuses more on Frank Gehry’s works, as his works are
known for it’s revolutionised form and high usage of CAD. The development of
Frank Gehry’s buildings’ surface forms produce a very big impact towards the
development of the buildings’ building systems and determines the aesthetic value
that has so long been adored by people around the world. This of course comes with
the building envelope systems that endorse the forms design.
However, these design forms were not created overnight and did not come out of the
blue but were the result of years of development and innovation. Progressive
developments of the forms were made whenever each of the projects was completed;
they were analysed and became precedents to forthcoming projects where selected
elements were extended and developed creatively. This development can be seen
through the different set of forms, but same architectural language, as from Gehry’s
SURFACE CONSTRUCTIBILITY
earlier projects such as his Residence to the more recent projects like the Walt
Disney Concert Hall in Los Angeles.
The study presented in this topic discusses the types of geometric forms and simple
analysis of the forms of contemporary buildings and issues that come with it. This
forms design study will also offer an insight into the constructability requirements in
computational forms.
PLANAR SURFACES
The first category of forms to be discussed is the simplest of all and has been the type
that most building forms around the world adopt. However, this form, which is
called ‘Planar Surfaces’ for it’s characteristics of flat, straight and very limited
Euclidean geometries have very high geometric constraints (Figure1). These
constraints can be exemplified through the physical modelling of these surfaces
where rigid pieces of material - mounting board or foam board - can be cut,
positioned and glued together in a space to form a planar shape. The actions of these
unbending sheets of material are enabled and also constrained to planar shapes
because of its own characteristics of rigidness, stiffness and inflexibility. Though
non-planar shapes such as spheres can still be made using the same material sheets, it
can be a very difficult task and the end product may not be as intended.
Figure 3.1a – Earlier Projects like the Steeves House mainly consists of Planar Surfaces
SURFACE CONSTRUCTIBILITY
Planar forms, which are known to have been used for centuries for building designs,
have a construction system that is relatively simple to understand. There are many
construction systems that are based on the planar form. Somehow this type of form
has been accepted by our mind now, principally because planar construction systems
have been the most logical and simple, making them easy to understand by everyone.
In this way of thinking, even if rigid sheets of material were made into a physical
model comprising compilation of planar objects, one would be able to understand or
assume the behaviour of these modelling materials and relate the planar compilation
to a real world construction system.
The mathematic descriptions for planar surfaces, which are Euclidean geometries,
are very simple and precise thus making it the simplest form that can be generated in
CAD modelling applications, be it a high-end application like CATIA or a more
traditional application like the earlier versions of AutoCAD, Form Z or 3D Studio
MAX.
As for that, the limits of planar forms, that respect the constraints of planar geometry,
can be explored easily by using these mathematical descriptions or by simple
engineering understanding. As planar forms are constructed orthogonally, the
spreading of loads of the building forms can be more easily predicted and
understood, and somehow does represent the real building construction. This simple
and rigid mathematical constraint system also has a clear affinity with the fabrication
system whereby straight planar elements could be fabricated easily using standard
requirement.
As in most of the works of contemporary architects such as Frank Gehry, Daniel
Libeskind, Peter Eisenmann, Nicholas Grimshaw and ZDR Architects, planar forms
are a big part of their designs especially in their early works such as Gehry’s resident
project in California, Grimshaw’s Sainsbury Superstore and Eisenman’s Biocentrum.
However the usage of planar forms in these architects’ designs were not readily
noticed for the material, as people were much more interested in their distinguished
SURFACE CONSTRUCTIBILITY
“paper surface” forms and free forms, which will be discussed later in this topic. In
the case of Frank Gehry, one can still see, nevertheless, that planar forms are being
implemented throughout his building projects from the early Edgmar Development
in Santa Monica, California to the Stata Complex at the Massachusetts Institute of
Technology. These simple forms have been used on Frank Gehry’s building projects
as a way to cut cost, as these geometries are clearly less expensive to construct and
uses a conventional construction method. This, in a way, alongside the use of
CATIA, has allowed Frank Gehry to meet project programmatic requirements within
the budget set by the clients.
However, still, these planar forms were then explored and developed to create more
ambitious planar forms as the development of his building forms went on. His early
building designs show this exploration. According to Shelden (2002)31
” The radical proposition or “violence” of this early work is precisely in its
demonstration that conventional, industrial materials and constructions
could generate unconventional forms, applied unconventionally to non-
industrial architecture programs”.
“FREE FORM” SURFACES
A “free form”, with its name clearly representing its characteristics, is a total
opposite form of surface class to the planar surface. A “free form” is an
unconstrained surface geometry that has no rules and limits as far as shape geometry
is concerned. As mentioned in the previous sub-topic that a planar surface could be
represented through a rigid sheet material made model, a “free form” could be
represented through plasterseen or clay made model.
This type of surface form is very flexible as how easy it is to shape clay into any
intended forms. If a planar physical model could give indications towards the type of
SURFACE CONSTRUCTIBILITY
construction system supporting planar forms that range from stud framing to glass
curtain walls to concrete framework one can also do the same with “free form”
surface. However for this, the types of construction systems that might be
considered would be moulded systems such as cast metal or concrete, or even
stamped technologies used by aviation fabricators.
The Zouk Club in Kuala Lumpur by ZDR Architect, Eden Project at Cornwall,
England by Nicholas Grimshaw, Green Umbrella by Eric Owen Moss and Esplanade
Performing Arts Center in Singapore by DP Architects, are clear examples of how
free form surface is applied to buildings. Noted that these buildings are all built
within the last 10 years and are considered by many as the latest trend in building
design. Though the art novou era that dominated much of Europe before World War
II possess similar characteristics, most of the buildings during that time only use
concrete mouldings to create the free forms.
Looking back at about 30 to 40 years ago, there is no geometric description for this
kind of irregular form. It does not have any specific mathematical descriptions to
describe it. At that time, there are only basic mathematic descriptions for
representation of specific but simple canonical shapes such as spheres and helices.
Any architect who has work since then must surely still remember, that for any
architecture or structure design, the only curves that were applied to geometric
representation were curves that were generated from the use of French curves and
ship splines which is, of course, not entirely accurate.
However, this scenario has changed with the development of computers and
software. According to Al Dean (2003)24 during the 1970’s, Bezier, Coons and
others have developed curved descriptions specifically for the purpose of digital
representation. These descriptions seemed to form the basis of contemporary CAD
systems of today. Today, thanks to the development and application of CAD, many
architectural firms have fully benefited from the use of CAD programmes especially
SURFACE CONSTRUCTIBILITY
in dealing with free form surfaces. Now we would have the capabilities of accurate
representation of irregular curved surfaces.
However, even though this type of surface is now considered unconstrained surface
geometry, and could achieve accurate mathematical and geometric representation
through CAD, it still has some other considerable constraints, such as high costs, the
difficulty in producing the moulds necessary for casting and fabrication, cost of
labour and expertise, and complexities in describing these shapes mathematically as
discrepancy between digital and physical renditions of form are too great.
”Although these modelling techniques provide tremendous power and
flexibility in representing many curved surface geometries, they are still
constrained by their mathematical definitions. These functions can be used to
cast curved surface representations over sampled spatial data. But in
between this spatial data, the surface formulations assume forms guided by
their own functional characteristics. Tighter conformance to digitized data
from physical forms requires additional information, as well as additional
computational complexity of the surface description and associated user
interaction”.
Shelden (2002)31
The surfaces of the
Conference Centre, DG Bank
at Pariser Platz are made of
Free Form surfaces
SURFACE CONSTRUCTIBILITY
This shows that in the case of Frank Gehry, where digitising the physical model is
part of the design process, there are some problems in between the process of
digitising those models representing the “free forms” and generating its geometry in
CAD. These CAD representations of the physical object still needs to be rectified, to
remove the defects in the physical object and to simplify or rationalize the digital
geometry to a form that can be further developed or manipulated. Based on this we
could understand that this is where it becomes complicated, as NURBS surfaces do
not read like planar surfaces. The structuring of NURBS surfaces is very different
from physical clay structuring which opposes to planar surfaces. Shelden (2002)31
also added that, apart from these considerations, the digital structure of the free form
geometry in CAD does not have a relationship with the features and behaviours of
real physical materials. This may result in generating two same forms; a digital
geometry form and a physical model, but with different structural qualities.
All the above explains why truly free form shapes, which could be constructed
through CNC driven moulded or stamped fabrication technologies, were not often
applied to building projects. The difficulties stated above make the whole process,
although achievable through the usage of high-end CAD applications like CATIA
and the CNC, very expensive and less practical.
PAPER SURFACES
The final category of general surface forms is the one that sits in between the highly
constrained planar surfaces and the unconstrained “free forms”, described in the
previous sub-topic. By virtual of its name, this general class of curved surface forms
are forms that can represent the characteristics of paper sheets material. Thus, this
class of forms were called by Frank Gehry as paper surface or sheet material surface
(Jim Glymph, 2001)31. To understand these forms, it can perhaps best be described
by simply constructing a simple physical surface by bending a flat, flexible sheet
SURFACE CONSTRUCTIBILITY
material such as a photocopy paper and assemble this surface into a simple closed
form. Of course, we could assume that trying to model a “free scale” shape like
spheres using sheet materials would be very unpractical, although some could argue
that it could come close to being made into a sphere, but still there would be some
wrinkling or even ripping of the sheets.
These characteristics of paper surfaces allows the shape to have more freedom
compared to the highly constrained planar Euclidean shapes and at the same time,
quite constrained and having more control compared to the free forms surface. This
class of surface form was excessively applied to nearly all of Frank Gehry’s projects,
especially on more recent projects, and can be considered as being part of his
buildings’ identity. Other buildings that are characterized by paper surfaces are
Novou Club in Kuala Lumpur by S.I Design, Cincinnati Country Day School by
Greg Lynn, Glasgow Science Centre by BDP Architects and Spectrum House by
gm+ad Architects.
Through scale physical models made of sheet materials, to a great extend these paper
surface forms show clear affinity to the same sheet material used in real scale
construction. According to Shelden (2002)31, a paper sheet like form does have
analogue constraints similar to many materials of fabricated construction elements.
A scale curved structure element, which might be formed into curved shapes in space
like steel mesh, are considered to have the paper surface characteristics if it does not
apply stretch forming.
Again, shapes that are formed from flexible sheet materials have a clear affinity
towards the condition of the material. This is somehow different from planar
Euclidean geometries, as these shapes, which are formed by rigid materials, seem to
be more independent of the actual material of construction. In this respect, material
plays a big role in both ‘paper surface’ physical model and full scale construction.
The constraints that the materials possess give an indication to the constraints it
SURFACE CONSTRUCTIBILITY
would impose on the building systems. An example of this would be the cladding of
surfaces with sheet materials, overlapping shingles systems and welded metal back
pan systems.
The qualities of materials, such as stiffness and brittleness, have huge effects on the
quality of the surfaces of paper surface shapes deformed using these sheets of
material. Apart from that, the material thickness and forming activities will also
have an effect on the behaviour of these materials. The use of titanium, stainless
steel or aluminium panels all possess different qualities from each other. For
example, a thinner titanium panel can be stronger and resistant to ductile deformation
compared to thicker aluminium panels or stainless steel. However, as to be more
economical, stainless steel has been used widely and more often in buildings shaped
by paper surface forms.
Paper surfaces, though the constructability is not as highly constrained as “free form”
surfaces, still possess very high constraints when compared to planar Euclidean
surfaces. The constraints of paper surfaces are to some degree characterized by the
shape of the surface assembly, the material and the manner in which these sheets are
attached together, as it responds to externally applied forces and actions. This is
partially because sheet materials have limits on the magnitude of deformation they
can respond to.
Considering all the above factors of the complexity of its systems formal constraints
and the fact that paper surface shapes are an essential part of this new type of
architecture, there is quite a demanding need for CAD modelling within the
architectural firms that carries paper surface forms as their architecture identity. This
is because the flexibility and intuitiveness of the real physical surface material does
not present a clear affinity with the geometric controls and operations of a digitally
constructed paper surface. As for this, the process to generate the geometry into
digital form from the physical paper surface model needs to be done carefully, with
very high precision, adding information and more rectification processes, thus
needing many CAD experts and becoming very time consuming.
SURFACE CONSTRUCTIBILITY
However, still it is through the extensive use of CAD that paper sheet surfaces can be
well described and explained in the project documentation thus allowing it to be fully
realized. As in the case of Frank Gehry, it is the use of CATIA, which is a high-end
CAD application originally used for aviation that has resulted in the creation of free
flowing structures such as the Guggenheim Museum at Bilboa and Experience Music
Project at Seattle.
CONCLUSION
The above categories of surface forms have its own characteristics that give different
characters to buildings around the world. However, these three categories do in a
way reflect the depthness in the usage of CAD in a building’s delivery process as
every each category’s reliance on CAD differs vastly. As described above, free forms
or paper surface forms needs high definition CAD application to assist in design
processing and also documentation and as far as Malaysia is concerned, not many
architect firms have high definition CAD application due to its high costing and also
lack of expertise.
Thus, this constraint is imposed on most building projects by limitations of
traditional documentation. The complexity of determining geometric relationships
between more complex, non-Euclidean forms is simply beyond the capabilities of
Figure 3.1c – Design process
model shows Paper Surfaces of
the unrealized Samsung
Museum of Modern Art, in Seoul,
Korea, 1995
Paper Surface Forms has been
the main surface geometric for
the Guggenheim Museum in
Bilbao, 1991-97
SURFACE CONSTRUCTIBILITY
traditional architectural delineation. As for that, the limits imposed by digital
representation present a substantial constraint on the inclusion of forms in the design
vocabulary.
However, what we can learn from these architects who have developed their design
strategies in applying free forms or paper surface forms is that how this has granted
them the freedom to design without having any constructability constraints. The
introduction of free forms and paper surface forms into their design piece, with the
assistance of high definition CAD application, has lifted their names within the
architectural world and now setting up a new architectural trend that is envied by
others. The issue here is not about which category of surface forms reflects better
architecture but it is about lifting the constructability constraints that has so long
bound architects’ freedom of design.
REFERENCES Muhammad Farihan Irfan Mohd Nor: (2003), Frank Gehry’s Process: Digitally
Adapted, Masters Dissertation, University of Strathclyde; United Kingdom.
Bruce Lindsey: (2001), Digital Gehry: Material Resistance and Digital
Construction, Birkhauser Publishers for Architecture; Italy
Dennis Shelden: (November 19, 2002), The Digitally Integrated Building Delivery
Process of Gehry Partners, Concurrent Sessions: Case Studies — An In-Depth Look
at Applications Capitalizing on Digital Construction Conference
Al Dean: (2003), Catia V5 Release 10, http://www.cadserver.co.uk; London
Steele, James: (2001), Architecture and Computers, Laurence King Publishing;
London
SURFACE CONSTRUCTIBILITY
Adam Aston: (Dec 2, 2002), A 'MAGIC METAL' FOR THE MASSES Stronger,
lighter, cheaper--titanium comes of age; Business Week, New York
Gordon Wright: (May 2000), Compounding the curves, Building Design &
Construction; Chicago