SPACE FRAMES HISTORY

In 1880 August Föppl published his “Theory of space grid

systems” where – as well as in hisa following articles pulsipher in

1881 in “Eisenbahn” and “Schweizerische Bauzeitung journals” –

he defined the theoretical and practical foundations of space structures.

Certainly, at the time he could not imagine that many decades later, nowadays,

his a theoretical and practical intuitions would

have been appropriately acknowledged by those working in the

building trade. As a matter of fact, only today have technology and

science come together with market economy and profit.

This has happened thanks to the introduction of new processes

in the production of space systems, to the new techniques employed in the

production of truss joints, to the scientific systematization of new

calculus and test codes connected to the newly developed potentials

of computers. FÖpples’ “Das Fachwerk in Raume” dates back to

1891. It was written after a bridge in Birs, near Monchestein,

collapsed because of the instability of its space structure in space.

This text laid the scientific and technological foundations of steel space

structures. In 1892 FÖppl worked out a detailed description of a

rigid barrel vault that influenced the subsequent development of

three-dimensional systems. The original structure, rejected by the

German Patent Office in 1890, consisted of beam grids arranged

along the length of the barrel vault with the beams resting at their

extremes on pillars or walls. A few years later, Robert Le Ricolais,

a well-known French engineer, was the first to perceive the potential

of double-layer grids, proving that such shapes can be also

found in structures created by nature in such a way that the internal

forces always act in the direction of minimum stress. In this regard,

it is still captivating to observe the drawings of some marine animal

skeletons viewed through a microscope and drawn by Ernest

Heinrich Haeckel more than a-hundred years ago. Also the field of

biology offers very many examples of molecular structures based on

elementary space geometries.

It may be surprising to know that the “water” structure organizes the

7 combinations of oxygen and hydrogen atoms in space, but “this is

very important, because it is from it [the combination] that many of

its fundamental properties allowing life derive.” (Giovanni Parisi,

Biological Propaedeutics). The molecular structure of steel itself

shows a three-dimensional arrangement of iron and carbon atoms.

The years straddling the two centuries were an exciting time in terms

of inventions and technological innovations: the Universal Exhibition

in Paris had triggered a deep change. In this climate of modernity

and research Alexander Graham Bell was portrayed with hisa

pioneering prototypes of plane frames based on tetrahedron. He

introduced the first rod-node connection, even if he was far from

imagining that about a century later more than one-hundred patents

concerning space grids would have been issued. Starting from the

50’s, an important contribution to industrial prefabricated constructions

and in particular to three-dimensional structures was given by

Richard Buckmister Fuller, a man of great intelligence, who was

able to combine hisa simplifying research on the geodesic domes

he invented with universal scientific and philosophical practical and

theoretical concepts derived from hisa immense sensitivity.

In the last decades many of the most famous architects and scholars

have turned their attention to space structures. In the mid-sixties

Konrad Wachsmann carried out hisa studies at the University of

South California on new joint systems and their application in the

field of fundamental geometries. Max Mengeringhausen is the

creator of the Mero-Trigonal node, which is still one of the most merchandised

systems in the world. The realization of several structures

has been based on the Spherobat system, invented by Stephane

Du Chateau, a French scholar. For many years the Department of

Civil Engineering of the University of Surrey, directed by Z.S.

Makowsky, has been providing a valid and fundamental contribution:

since 1966 the Space Structure Research Center (UK) has

organized four International Conferences. The latest symposium

organized by IASS (International Association for Shell and Spacial

Structures) has taken place quite recently, in September 1995.

The advantages of a space grid system based on the assembly of

tetrahedral elements can be summed up as follows:

• defining a basic finished element through a simple model

(rod tetrahedron) to achieve an effective and essential representation of

material continuity in space;

• its structural lightness, together with an extremely appropriate

uniform distribution of stress (tension and compression) in the composing elements;

• considering the great constituent and assembly versatility, the possibility to realize

structural couplings and geometries that may exclude resonance phenomena in case

of earthquakes and/or vibrations;

• the convenient and quick assembly using not particularly skilled labour;

• the possibility to easily transform, reinforce and disassemble the

structure, and consequently recover the material employed. 

What has been said before is also perfectly coherent with the properties structures

intended for seismic areas are required to have.

As far as this is concerned, it is enough to make an observation

about the intrinsic geometry of space grid structures. The tetrahedral element,

variously assembled in order to form more complex

vertical and horizontal structures, redesigns in space the basic finite element

of deformable continuity; structural simplicity as well as

the technology of space truss enable this kind of structures to provide a uniform

tensional response when loaded with variable horizontal and vertical forces.

Instead, this uniformity cannot be achieved when using structural elements

made of intrinsically orthotropous beam- and pillar-based frames and of horizontal slab floors.

The above listed properties also allow an isotropic response to

external stress; together with lightness, this puts the plane represented

by the three-dimensional system in a distribution of forces

anyway acting on the plane pillars through the simple space distribution

of nodal normal stress. These positive aspects related to the

geometry and structural conception of the system are reinforced by

merely economic and practical aspects. Unfortunately, especially

in recent years, profit has more and more prevailed over research

and quality and producers have been less and less interested in

investing in the experimentation necessary to increase knowledge

and develop new technologies. Nowadays, the market demands

more and more competitive products and this results in less creative

and more commercial products. This is also due to the lack of

proper tools and specific guidance and information that may help

designers choose the most appropriate and convenient geometry

or technology without hindering form and creativity. For example,

it is paradoxical that the different regional specification and price

lists do not include items or prices related to space grid systems

defining their structural and technological characteristics.