Structural Engineering International

ISSN: 1016-8664 (Print) 1683-0350 (Online) Journal homepage: http://www.tandfonline.com/loi/tsei20

From Structural Performance to Performative

Structures: New Narratives in Footbridge Design

Mario Rinke Senior Researcher and Lecturer

To cite this article: Mario Rinke Senior Researcher and Lecturer (2018) From Structural
Performance to Performative Structures: New Narratives in Footbridge Design, Structural
Engineering International, 28:4, 408-417, DOI: 10.1080/10168664.2018.1477481

To link to this article: https://doi.org/10.1080/10168664.2018.1477481

Published online: 22 Oct 2018.

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From Structural Performance to Performative Structures:
New Narratives in Footbridge Design
Mario Rinke , Senior Researcher and Lecturer, Department of Architecture, ETH Zürich, Zurich, Switzerland.
Contact: rinke@arch.ethz.ch
DOI: 10.1080/10168664.2018.1477481

Abstract river conditions below can be crucial.

These technical constructions have
In most cases, bridges are an integral part of a grown, long-term development of been developed using empirical rules,
infrastructure. While for the Renaissance architects and engineers bridges were and during the Renaissance the obser-
part of the general infrastructure, urban bridges have become a natural vation and imitation of nature and
continuation of the city with its various layers of meaning. Technological her recognized rules determined the
advancement and scientific thought during the eighteenth and nineteenth culture of technical construction.
centuries brought the concept of efficiency and the domination of fabrication Referring to Vitruvius’s assertion that
processes into the design of structures; whereas in the past bridges were often “all mechanical devices are made
considered as technical devices with a clearly expressed inner logic of form, today from the constructiveness of nature,
new forms of development for structures in footbridge design—in combination and they are taught by master nature
with modern materials—are resulting in greater effectivity and broader through the rotation of the universe”,2
functionality. In order to shape the spaces on and around bridges, the load- many builders of the modern age relate
bearing structures are often made visible above the deck, manipulating the spatial their studies of nature with their ideas
experience either directly or through a diagrammatic articulation of the structural in construction. This practice can be
behavior in the arrangement of the bridge’s components. Recently there has been found as early as the thirteenth
an intentional shift away from common perceptions of bridge design through the century, in the many sketches of
manipulation and dissection of structural typologies, leading to new Villard de Honnecourt (ca. 1200–
interpretations and multilayered narratives. The aesthetic conception of the user’s 1235) that study a sawing machine, a
perception has been shifted away from the subtle reading of a familiar structural crossbow and a pigeon next to each
grammar toward a more direct influence on the user through the creation of other.3 The principles derived from
clearly expressed structural figures. The structure itself is now not only more nature led to the creation of patterns
visible and actively involved in the spatial experience but it is also designed to for the structural components which
suggest a greater form of immediacy through its increasingly performative formed bridges and roofs, among
character. This paper reflects the changing understanding of the role of structures other constructs.4 Bridges in cities are
in the design of bridges, and examines the ways in which the strategies for a somewhat different case; their
contemporary footbridges can be contextualized both historically and aesthetically. notion has to be extended to their
Keywords: historic structures; aesthetics; structural concepts; architectural space; specific role in the built world around
performance them. In the case of pedestrian
bridges, an important design aspect is
fitting in with the surrounding build-
Introduction (1404–1472), bridges were “mainly a ings in a way that provides both a
part of a road”,1 whereas Andrea Pal- representative quality and places on
Bridges are technical artifacts; serving ladio (1508–1580) applied the same the bridge where users can linger.
the simple purpose of connecting basic Vitruvian principles to bridges Between roads and squares in his
places and continuing roads artificially as he did to buildings: they had to be third book, Palladio describes many
across water, valleys and urban beautiful, as well as functional and different bridges, one of which is a
spaces, they are first and foremost durable. For bridges, the choice of project for a bridge in a city center
practical devices. If designed with location is extraordinarily important, that provides “three streets, the one
only this indispensable aspect of rel- since this affects all aspects of the in the middle wide and beautiful,
evance in mind, a bridge will be artifi- design—not only the endeavor to con- those on both sides a little more
cially placed in an existing struct the bridge must be a consider- narrow”, with spaces to walk, meet
environment and built with artificial ation, but also the object itself and and make business in the arcades and
means. However, as all building how it fits into the surrounding buildings on the bridge (Fig. 1).5 The
materials and components are some- environment. Its beauty must not only bridge is designed to reflect the cultural
what transformed to be used in their be reflected by its inner structure and importance of both the city itself and
intended way for each specific location, outward appearance, but also in terms the central location, thus fulfilling its
these transformations often reflect the of both its integration within its aim “to serve and enrich the city”.
skillful tradition of technical and artis- environment and its usability, which The bridge can only be used by ped-
tic refinement. must also include the understanding estrians and is meant to serve multiple
that it should support as diverse a purposes: transportation, strolling,
In most cases, bridges are an integral
range of users as possible in the safest socializing and commerce. Together
part of a grown, long-term develop-
and most convenient way. Bridge dura- with the buildings on each side it is a
ment of infrastructure. For Renais-
bility is also a factor affected by public square, built from the elements
sance architect Leon Battista Alberti
location, since a particular span or the of the urban fabric—not a technical

408 Scientific Paper Structural Engineering International Nr. 4/2018

 Such structures were designed to
satisfy clearly defined aims; conse-
quently, strong principles of logic and
an absolute focus on functionality
defined their appearance. The absolute
priority of functionality in the service
of transportation or defense governed
the use and arrangement of the parts
in these constructions—therefore,
they can be considered as “technical
devices”.
Because of the above factors and the
further complication of the application
of new building materials, bridges
became the exclusive domain of engin-
eers, who often reduced their design to
an isolated problem that, like any
modern structure, has to be rational—
that is, it must be reproducible and
reflect all the scientific knowledge cur-
rently available.8 Neglecting the inte-
Fig. 1: Bridge proposal by Andrea Palladio grated role that structure itself plays
Andrea Palladio I quattro libri dell’architettura, Venice, 1570, 3rd book, p. 25 (Swiss in buildings and bridges, during the
Electronic library/ETH library Zurich) design process the engineers would
focus almost exclusively on perform-
ance. This change was a paradigm
object signaling a break in the city They were responsible for both the
shift in the culture of structural design
landscape such as a river, but rather a civil and the military infrastructures,
from the topos of the engineer artist
continuation of the city with its which connected the two realms of
to the engineer scientist. The introduc-
various layers of meaning. If this form their work and thus their ways of think-
tion of these radical principles during
of bridge is an urban object at all— ing: On the one hand, when building
the institutionalization of the discipline
that is, a significant point in the fabric bridges these infrastructural experts
reflected the engineer’s new self-
—then it is one of strong linearity saw themselves in a tradition of archi-
conception: to be acknowledged as a
with its boundaries, rather than an tecture, developing their designs in
scientist rather than as an artist.9
abrupt change in material and func- connection with many contextual
tion. Starting at these early modern layers—such as classic typologies, Within this technical realm, foot-
approaches to integrating footbridges relation to and embedment in the bridges were often showcases of what
into the urban context, important environment and durability—when was technologically possible, what
design factors are now discussed in making choices on the materials and modern materials could do and how
the development of footbridges up to overall geometry. As these construc- scientific approaches could create a
the present day. tions are long-term investments, they concrete expression.10 In this sense,
have to be—apart from their long- these technical objects were self-refer-
term usability—representative of the ential, founded on scientific reason,
Structures and Artistic Design cultural self-conception of the state. material economy and industrial fabri-
With the new conception in the intel- cation. The isolation of the engineer
Formation of a Particular
lectual programs at the newly from cultural aspects and the history
Character founded engineering schools, the tech- of architecture in his education—the
Bridges are built in a range of configur- nical design of bridges was no longer isolation of his understanding as a
ations; larger bridges with broader car- connected to the art and traditions of (scientific) designer from thinking in
riageways can allow both vehicles and building, but rather to the sciences of terms of a contextually complex
pedestrians to cross, whereas compara- mathematics and physics. Engineering overall design—also often meant the
tively smaller bridges are restricted to students were not taught by experi- isolation of the structure from its
vehicles or pedestrians only. Foot- enced, well-known master builders environment, the bridge from its
bridges have had their own distinct who can be considered architects and context.
identity from around the end of the engineers at the same time, but increas-
eighteenth century6 as a result of the ingly by natural scientists. The reorgan- Like pavilions, footbridges were illus-
advancements in technology and scien- ization of engineering education trations of industrial modernity rather
tific thought that took place during the brought about a reorientation in the than necessary and purely functional
Enlightenment. This is also the period very understanding of technical elements of an urban infrastructure.
during which the first engineering design itself.7 On the other hand, Urban footbridges have always
schools were founded throughout these engineers working on civil tended to have a decorative character,
Europe, and engineers—mostly service infrastructure were also but what has changed over time is
employed for public road and bridge assigned to military projects, which their intellectual context, namely
construction—enjoyed an education encompassed temporary bridges as where they are embedded and what
that was increasingly based in science. well as structures such as fortresses. they are connected to in a given

Structural Engineering International Nr. 4/2018 Scientific Paper 409

Fig. 2: Le Pont des Arts, Paris, by Louis-Alexandre de Cessart and Jacques Vincent de Lacroix Dillon (engineers) and Louis Gerald Arretche
(architect), 1804 (© Mbzt/Creative Commons)

urban context. Therefore, it can be materials have become increasingly construction typology that was based
simply asked: what is their architec- capable of facilitating larger spans on fabrication and articulated with
tural and constructional language? It with smaller dimensions, and new com- well-defined and often repetitive com-
has often been the expression of binations have been tested and proven. ponents and connections, one of the
novelty, with new architectural forms Equally important but perhaps less main design goals was the variation of
(mostly referencing traditional con- obvious is the fact that while loads for typologies—especially the physical
cepts) and construction materials other bridge types have increased dra- form and more specifically the
leading to dramatically new arrange- matically, for example with denser expression of the structural arch as
ments, spans and scales of the construc- traffic in urban areas and the use of the classic form of bridges. In Europe,
tion components (Fig. 2). The change heavy locomotives, the load require- the academic engineering culture
was particularly radical during the ments for footbridges have remained favored single systems and adopted
introduction of early iron structures in relatively constant. Many different their basic form to the appropriate situ-
the early nineteenth century.11 The dis- ways to translate the increasingly ver- ation by specifying the geometry
connection of these bridges was satile properties of materials into orig- according to the boundary conditions
twofold: the new construction inal structural forms have been and the loads to be carried. In this
materials formally separated them devised. An early strategy was to scientific understanding of the exten-
from the surrounding buildings, and overlap structural systems in order to sively controlled engineering design,
the new scientific approaches com- increase the overall capacity. Many the constellation of forces along with
bined with industrial fabrication proposals and built bridges from the necessity in the choice of materials
brought about an new inner logic of early railway period in the United determined structural forms.
form.12 While the arrangement of the States (US) were based on this strat- In his widely known book, Philosophy
components and materials within the egy. This pragmatic approach followed of Structures, published in 1958,
design concept of these bridges often the idea of adding structural resistance Spanish structural engineer Eduardo
directly reflected their method of cal- by combining and placing components Torroja (1899–1961) brings together
culation and fabrication, they can be and entire structural systems parallel design approaches that encompass
understood as diagrammatic structures to each other. However, this so-called both the properties of materials and
or assembly sets. “overlay” design often combined general structural concepts, reflected
systems of different stiffnesses but did both technically and formally.13 More-
Structural Narratives not fully activate them simultaneously. over, in the chapter entitled “The
The utilization of increasingly playful Nevertheless, this structural consolida- Beauty of Structures” he presents
and novel narratives for footbridges tion indicated more capable bridge one of the first theories of artistic
has been further encouraged over the structures, and this improvement was expression in engineering structures
past two centuries as technology has obviously one of the intentions of the developed by an engineer. While
continued to advance. Construction designers. After introducing a trying to establish a theoretical

410 Scientific Paper Structural Engineering International Nr. 4/2018

framework for structures in terms of notion of efficiency. He proposes the The visual impact, the consideration of
aesthetics, he considers the contri- concept of structural art as the bringing which has resulted in the development
bution of structures’ deeply embedded together of the ideals of efficiency, of such “real works of art”, is often
qualities as a form of art. During the economic feasibility and elegance.14 achieved with increasingly performa-
1920s, reinforced concrete was widely The gesture of a structure, perceived tive designs. What follows is a discus-
established as a fully functional build- by Torroja in terms of the capacities sion of a few selected contemporary
ing material, and later—especially of its composite materials, extends the approaches to footbridge design
after the Second World War—its fundamental engineering concept of whose composition is read closely in
applications began to demonstrate a efficiency—that is, assigning just order to understand their concepts
characteristic nature that led to enough material to a component and considerations.
numerous original projects in archi- according to resistance requirements
tecture and engineering. Coming that are determined via thorough cal- The Site
from its roots as a form of artificial culations. For many structural pro- Bridges are part of the built environ-
stone, reinforced concrete extended blems, the properties of new materials ment and as such must be considered
into a very different field of classifi- mean that using standard dimensions as architecture. Unlike furniture,
cation during the development of would provide more resistance than is which is in most cases formally self-
surface structures such as shells and actually necessary, and thus might referential and produced in a
folding plates.13 cause additional unwanted effects. In location-tolerant manner to be placed
the case of footbridges, modern and replaced anywhere and anytime,
Reflecting the late 1950s, which wit-
materials can potentially contribute to footbridges are important components
nessed the introduction of post-ten-
greater effectivity through the creation of the urban fabric. They intentionally
sioned reinforced concrete and its
of structures that have broader func- connect specific spaces in multiple
technological applications in bridge
tionality. Consequently, these struc- layers of their context. Often the
design, Torroja describes the surprising
tures are not just serving a basic design of a footbridge is articulated as
beauty of structures as often being
purpose but they are also performing a response to the surrounding environ-
based on the potential of new
in a deeper context, and thus their ment, the existing structures and their
materials.13 These astonishing struc-
expression becomes a design consider- materials and the particular history of
tures like slender shells and arches
ation. Contemporary footbridge the location. Unfortunately,
resembled their stone architectural
designs continue to push the concept approaches to formulating designs
predecessors, expressing a deeply
of elegance towards a formal narrative that are driven by the site context are
anchored harmony of well-balanced
that increasingly rejects the idea of rarely expressed by engineers. A few
vaults and massive stone-arch bridges.
pure structural functionality. Elegance exceptions however allow the gaining
However, Torroja felt that structural
is therefore not based on the concept of insight into the formal connection
harmony was largely undeveloped.
of economic efficiency but rather on of a design to its setting—that is, not
For him, the expression of bridges at
multi-functionalism. Load carrying just the space but the place and its
that time mostly aimed to “emphasize
thus becomes an incidental act, and a moment in time. Such examples can
the triumph and power of modern
multidimensional formality is devel- be found in the work of designers like
technique in the use of materials”13 to
oped as the ultimate result—all still Ney & Partners, a structural engineer-
combine strength and lightness:
within the constraints of economy and ing consultancy based in Brussels.
buildability. They describe the Poissy Footbridge,
(…) the impression of flowing strength for example, as an “intervention” that
suggested by the agile athlete who The need for footbridges as artistic “echoes the historic bridges of the
jumps easily without any sensation of contributions to the urban landscape site” and enables a “transformation of
difficult effort or labored technique, is nowadays regularly expressed. The Robinson Island into a public space”
suggesting indeed that the limit of his Landscape Architects Network online (see ii in Further Information). Tinta-
capacity lies much further off. […] It platform defines a set of functions gel Castle Footbridge creates a contex-
combines a childlike simplicity with a that modern footbridges fulfil: tual accessibility while enhancing “the
vibrant dynamic energy.13 visitor experience, enabling more
In a world that is mostly vehicle- people to discover the site and facili-
The structures Torroja describes oriented, these elements are a great tate its understanding” (see iii in
demonstrated the triumph of materials, way to facilitate motion in the chaotic Further Information). In this way, foot-
expressed in excitingly slender com- urban environment, where increasing bridges are not only granting access to
ponents that casually mastered load traffic is a relevant issue. In terms of a space or allowing passage through a
transfer. Unlike the massive Roman function, footbridges must provide safe space, but they are also modifying,
viaducts, these new slender concrete and easy access across streams, roads, expanding and deepening the charac-
arches turned the promise of eternity railroads, and so on. Although they ter of these spaces and their surround-
and robustness into a forward momen- are built more to a human scale (com- ings. They can continue the urban
tum which promised a path of techno- pared to highways and vehicular fabric and make it readable in different
logical advancement—namely, that bridges), pedestrian bridges still make ways. The designers developed the
there would be more to come. a big visual impact on the landscape, Smedenpoort Footbridges “as a ‘pro-
so aesthetics is very important to menade’ to meet that requirement.
Another theory was formulated by the ensure that this impact is positive. With The path has been conceived as an
American engineer David Billington that in mind, designers have turned element that embraces the existing
(1927–2018) in the 1980s, whose work these elements into real works of art. bridge and building” (see iv in
connects structural beauty with the (See i in Further Information). Further Information). In the case of

Structural Engineering International Nr. 4/2018 Scientific Paper 411

the Esch Footbridge, the intervention Suspension bridges, such as the Tier- center of both sides. These openings
has even changed the existing local gartenbrücke over the Mulde in are lined with plates which host the
character substantially at “both [the] Dessau, have their load-bearing struc- hanging system. The footbridge
urbanistic and [the] social level” tures above the walkway, forming a becomes a true urban window” (see
(Metaform Architects, Ney & Part- characteristic corridor through a vii in Further Information). An
ners) (see v in Further Information). series of cables: “The hangers define alternative shown in the concept for
a walkable space offering a special another footbridge in Shenzhen is to
visual experience when crossing the make the designed space visible
Spatial Arrangement river”.15 This emerging space, which through a sort of cladding: “A wide
subtly changes with different viewing cantilevered roof, which leans on the
When approaching a footbridge, the angles from the walkway, can be arch, gives the bridge its unique silhou-
user gets the first sense of what it is in further modified, extended and specifi- ette” (see viii in Further Information).
the context of its environment, but a cally expressed if the deck is not
further connection to it is the percep- A spatially less complex but more
straight but curved. Such a design can
tion of it as a space. Apart from the formal approach is the expression of
run along standalone pylons or
sensual connection of the user to the the structural behavior through the
between one or a few arches, making
site, this must be considered as an visible load-bearing components.
possible stronger formations of spaces
important driver in contemporary foot- Unlike when focusing the design on
through the curved walkway, as
bridge design, as the creation of an the space as an entity, the perception
explained by Stefan Polonyi for a foot-
internal spatial perception for users of the particular structural perform-
bridge proposal over the Fulda in
ance is mostly limited to singular com-
while they are on or crossing the Kassel: “The curved line of the
bridge is often stressed as a key ponents or parts of the structure. A
walkway passes through the arch with
aspect. As demonstrated by the Ver- formal arrangement of a series of com-
a spatially perceivable changeover
ponents penetrates the open space and
boekhoven Square Footbridge, iden- turning the arch figure acting statically
tity is created when a footbridge “is adds a rhythm, a sense of organization
in plane into a spatial, dynamic
and/or an extra level of physical pres-
more a public space than an engineer- element”.16 From this developed
ing structure” (see vi in Further Infor- ence and detail. This can provide a
space, connections can be integrated
mation, Fig. 3). Therefore, the further narrative for the visible layers
through specific views, as seen in the
components of the bridge’s structure of the bridge, as seen in the footbridges
Pedestrian Bridge Time Tunnel Shenz-
at the Expo Hanover developed by the
are mostly arranged above the hen: “Large openings are formed in the
walkway. engineers at schlaich bergermann

Fig. 3: Verboekhoven Square Footbridge, Brussels, by Ney & Partners and Moritz & Simon Architectes / MS-A, 2014 (© Serge Brison)

412 Scientific Paper Structural Engineering International Nr. 4/2018

Fig. 4: Expo Hanover, by schlaich bergermann partner (engineers) and Gerkan, Marg and Partners (architects), 2000 (© Axel Hindemith)

partner and the architects at Gerkan, been turned into a diagram of what is holds true: a strict, almost formulaic
Marg and Partners (Fig. 4). The team happening “inside” the bridge or its process, based on a mathematic algor-
wanted to express, beyond the struc- structure. When aiming to present the ithm, can ultimately yield surprising
tural functionality, a sense of perform- rational character of a bridge, it can results. In fact abstract principles are
ance: “In the case of such a structure only be decorated or formally designed an effective means of discovering new
above the walkway, the flow of forces according to its true behavior; it should forms – convincing, irrefutable forms,
is quite literally visible and can be only speak about itself. such as Pauli or Schwedler trusses in
counted down to the very last detail the nineteenth century or, in more
Many of the early iron railway bridges
in the number of ties”.17 recent times, Musmeci’s log-cos curve.18
in the mid-nineteenth century had their
truss structures above the deck and
perfectly demonstrated the structural A powerful way to modify these basic
Structural and Formal Ambiguity concept behind them. These iron forms and adopt additional conditions
Displaying the structural performance trusses are literally materialized dia- is the introduction of ruptures or com-
of a bridge plays with the concept of grams of theoretical idealized force plications. Normally, the straightfor-
minimalistic structures—designing flows. Therefore, these structural pat- ward process entails:
optimized components with perfectly terns are a quasi-display of the tools
distributed material—but should be which helped to establish them. Jürg “(…) calculating” form according to a
read as a dynamic play of forces. The Conzett describes the process of form neutral process. In practice, however,
structural functioning is expressed in development through abstract math- the ideal forms defined by abstract prin-
front of the user exactly as it is happen- ematical principles as a way to discover ciples can only be realized with a high
ing. The fictitious image of the “force new forms: degree of fidelity if the task is sufficiently
flow” is used to translate the inner narrow in scope. As soon as some com-
logic into the outer arrangement in When you begin a design by sketching plication is introduced, the ideal form is
order to make the structure “read- out ideas you have an intuitive sense “disrupted”. Dealing with such disrup-
able”, as though the constellation of of what the completed structure will tions – an integral part of the engineer’s
static forces is like chance images, an look like. But when you begin with a role – means adjusting the project in line
optical illusion (Vexierbild) that has general abstract principle the opposite with more subjective assessments.18

Structural Engineering International Nr. 4/2018 Scientific Paper 413

Fig. 5: Footbridge over the Mülheimer Strasse in Oberhausen, by Polónyi & Partners, 1997 (© Archive Polónyi)

As for other types of structure, this permanent loads, a disruption is intro- interpretation levels are possible. (See
concept has been adopted for foot- duced; the hangers then have to be ix in Further Information).
bridges, which—due to their particular arranged in a specific order to create
visual importance in the urban context the desired arch form, as demon- The deformation and dissection of
—are specifically designed and care- strated by the engineer Stefan structural typologies leads to new pos-
fully detailed and fabricated. Polónyi (1930-) in his design for the sibilities and interpretations, surprising
bridge over the Mülheimer Strasse and original narratives and unique
Analogous to the manipulation of
in Oberhausen (Fig. 5): “The arch expressions that reach beyond tra-
space through the articulation of
curvature was defined according to ditional structural images to manifest
both the walkway and its structural
the thrust line caused by the hangers contemporary visions.
components, the display of structures
and therefore shows a dynamic
as built diagrammatic patterns and Another rather elaborate project
appearance”.19
the underlying manipulation process takes this approach to a formal or
are profoundly different. Through a In other cases, the structural configur- even artistic level. The Pedro e Inês
purposeful confusion of one’s percep- ation refers to a basic structural type, Bridge by Cecil Balmond in
tion, the reading and understanding but what is visible appears to be incom- Coimbra, Portugal (Fig. 7) plays with
of the footbridge structure can easily plete. For their footbridge in Sion, Ney the concept of a structural arch as
perplex the user. This is classically & Partners designed a cable-stayed the classical bridge type but intro-
achieved through a deformation of bridge which—although of a type that duces a new reading. As Cecil
structural typologies, thus opposing had previously been built in the form Balmond describes in an interview,
expectations of familiar structures. A of the Alamillo Bridge in Seville, instead of providing a clear arch
very common strategy is the defor- designed by Santiago Calatrava and running continuously between the
mation of the classical arch typology. completed in 1992—is surprisingly supports, the bridge surprisingly
For an arch bridge, for example, different (Fig. 6): seems to break in the middle: “In
hangers are normally attached to the elevation it seems perfectly normal.
arch in equal horizontal spacings, con- The pylon is in the continuity of the It’s a simple arch. But as you move
sequently leading to a typical para- main central beam. To equilibrate the closer, half of it disappears into
bolic arch shape, which is the ideal main span, a counterweight has been shadow. It becomes really strange
form of a compression line caused located within the pylon structure. This and ephemeral”.20 The striking atypi-
by a homogeneously distributed avoids the use of a back-stay. By cal spatial impression is achieved
load. To manipulate the arch shape doing so, a spatial, contemporary struc- through immediate confrontation
but still form it through the actual ture is created in which several with the discontinuity of a normally

414 Scientific Paper Structural Engineering International Nr. 4/2018

Fig. 6: Footbridge Sion, Lier, Belgium, by Ney & Partners (© Ney & Partners)

continuous structure—the collision of demonstrated in the proposal for the The possibility of inscribing more, very
two structures, two spaces. This col- Pepsico footbridges in New York, different meanings in pedestrian
lision is a spatial drama, something developed by Ney & Partners: “The cir- bridges gives the basis of structural
that seems to be structurally and for- cular shape of the four bridges is a pro- design—forces and their formal
mally unreal and impossible: “Mr. tagonist for the square building shapes. expression—a very powerful influence
Balmond’s engineering genius has […] The bridge […] presents itself as in contemporary design. The
been crucial to the emergence of a a continuation of the building, the land- expression of structural components
new aesthetic of shifting asymmetrical scape and the sculpture garden”. (See can thus be extended to the process
structures that mock conventional x in Further Information) of informing the entire structure
notions of stability”.20 In other cases, the singular expressive through the play of forces. The
quality of the bridge structure is con- manipulation of this interaction of
sidered as a piece of art with a superor- forces enables a radical way of rethink-
Autonomic Performance ing structural types and expressions—
dinate autonomy, such as Stefan
Specific articulations and formaliza- Polónyi’s design for the bridge over as Cecil Balmond puts it: “I realized
tions of load-bearing structures for the Emscher in Gelsenkirchen: that engineering was more than calcu-
footbridges can lead to very strong sin- lating […]. I became intrigued with
gularizations which seek the opposite The alignment of the hangers and the the way that forces shaped things, the
of being immediately readable within form of the arch are derived from the way you assemble structures in series.
the canon of structures and the urban condition that there should be no note- The idea that we could help shape
context. Such structures can be con- worthy bending moments in the things – all that was in the air”.20
sidered as expressing an autonomic arches. The result of all these consider-
performance, both formally and struc- ations is the series of arch bridges, Conclusions
turally. In their dominance they are which can also be read as steel sculp-
not just placed between urban spaces tures in the landscape with a clearly The methods used for designing struc-
—they are also acting on them. This defined main function of spanning the tures have dramatically changed
gesture or autonomic performance is rivers or streets.21 throughout the last 200 years.

Structural Engineering International Nr. 4/2018 Scientific Paper 415

Fig. 7: Footbridge Pedro e Inês, by Adão da Fonseca & Associados and Arup AGU (engineers) and Balmond Studio (architects), 2007
(© CorreiaPM/Creative Commons)

Fabrication processes in the age of structural necessity with advanced typologies, which can lead to new
industrialization, the introduction of industrial fabrication possibilities. interpretations and multilayered narra-
the scientific approach to engineering Therefore, these straightforward appli- tives. The performing structure con-
education and thus the establishment cations of structural patterns and fabri- tributes not only to the functioning of
of technical thinking and design pro- cation technologies have celebrated the walkway as such but also to the
cesses that are a far reach from tra- their own inner technical narrative. space around it as the user traverses
dition and building culture, new tools the bridge. In the spatial drama of
Designing the space of a footbridge has
and changing public desires and structural components creating for-
become more important since the
demands in urban areas are all factors mally complex situations, the user is
acknowledgement that these structures
that have caused the context of struc- not only confronted with a carefully
can have a positive impact on the sur-
tural design to continuously transform. designed space but also increasingly
rounding built environment. In order
Not only does flexible structural think- with an overall design concept that
to shape and stimulate such spaces—
ing enable the engineer to deliver ade- aims to stimulate a response.
within the requirements and limit-
quate or even extraordinary proposals
ations of robustness and cost—the The aesthetic conception of perception
for a formal concept, but within the
load-bearing structure has often been seems to have shifted from a subtle
given design space of a footbridge—
made visible above the deck and used manifold reading of a familiar struc-
where there are comparably less struc-
in various ways to manipulate the tural grammar to a more direct influ-
tural requirements—the engineer can
spatial experience directly (e.g. a ence on the user through clearly
formulate a structural design even
series of hangers) or through a dia- expressed structural figures, moving
more directly and, since footbridges
grammatic articulation of the structural from the “readymade” to the “per-
are more visible in detail within an
behavior in the arrangement of the formance”. The structure itself is not
urban context and with the users’ per-
bridge’s components (e.g. truss pat- only more visible and actively involved
ception, even more articulated. Very
terns). A relatively recent trend is the in the spatial experience, but is now
often, footbridges have been designed
intentional disturbance of the designed to suggest a greater form of
as technical devices, serving a specific
common perception through the defor- immediacy. Like Frei Otto provoca-
purpose and based on a lower
mation or dissection of structural tively explained during the

416 Scientific Paper Structural Engineering International Nr. 4/2018

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Further Information
and subtly readable classical bridge [6] Baus U, Schlaich M. Footbridges. Basel,
typologies, the dramatic appearance Birkhäuser, 2008; 11. [i] https://landarchs.com/top-10-
of such footbridges seems to be in pedestrianbridges/, 16 April 2017.
[7] Kranakis E. Constructing a bridge. An
great danger of what Adorno called Exploration of Engineering Culture, Design, [ii] http://www.ney.be/project/21095.html
Verkunstung (artification), namely the and Research in Nineteenth-Century France
[iii] http://www.ney.be/project/tintagel-castle-
“immediate and unconcealed primacy and America, Cambridge, MIT Press, 1997; 108.
footbridge.html
of the perfectly calculated effect in [8] Rinke M. Vom Konstrukt zum Typus.
[iv] http://www.ney.be/project/smedenpoort-
typical products of the cultural Der Wandel der strukturellen Form von
footbridges.html
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Deutscher Kunstverlag, 2016; 70. [v] http://www.ney.be/project/footbridge-esch.
Structural engineers can find inno- html
[9] Rinke M. The infinitely shapable structure.
vation and inspiration between the In Before Steel. The introduction of structural [vi] http://www.ney.be/project/verboekhoven-
possibilities of creative structures and iron and its consequences, Rinke M, Schwartz J square-footbridge.html
their solid ground, between the prom- (eds), Sulgen; Niggli, 72.
[vii] http://www.ney.be/project/shenzhen-
ises and trustworthiness of technology,
[10] Chatzis K. Die älteste Bauingenieurschule footbridge-2.html
by using the tools and models for pro- der Welt: Die Ecole des ponts et chaussees
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(1747–1997). Bautechnik. 74(11): 776–789, 1997.
the “form-finding” process, the search footbridge-3.html
[11] Rinke M, Kotnik T. The changing concept
for equilibrium is not only a technical of truss design caused by the influence of
[ix] http://www.ney.be/project/footbridge-sion.
endeavor but also an act of cultural html
science. Proceedings of the First International
balance—a type of technological Conference on Structures and Architecture, [x] http://www.ney.be/project/
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