Materials in Tensegrity Structures by clinhvu

TENSEGRITY STRUCTURES & MATERIALS

VẬT LIỆU DÂY CĂNG

Lecturer:

Đặng Ngọc Anh

Students:

Vũ Chúc Linh Nguyễn Thị Phương Thảo

Hanoi Architectural University Institute of International Training & Cooperation 19KTT2 - Vật liệu và Kiến trúc (Materials and Architecture)

table of contents HISTORY AND DEFINITION + history + definition TYPOLOGIES MATERIALS + tensile component + cover + compressive component + feelings + conveniences, obstacles and applications CASE STUDIES + 1988 seoul olympics gymnastics hall + 2009 kurilpa bridge Q&A REFERENCES

HISTORY AND DEFINITION

In the beginning of the 20th century, more specifically 1919, the artistic and architectural philosophy Constructivism flourished in the Soviet Union as a rejection of the idea of vain and autonomous art. The movement promoted art as a practice for social purposes. Constructivism had a significant impact on the 20th century modern art movements, including architecture, graphic, industrial design, and so forth.

Tensegrity ’s discovery was directly influenced by Constructivism, namely Latvian-Soviet avant-garde artist Karl Ioganson’s “self-tensile constructions” shown in The Society of Young Artist 2nd Moscow exhibit in 1921

Art student Kenneth Snelson discovered Tensegrity in 1948 and 1949 after his inspirational introduction to American architect, systems theorist, designer, inventor, and futurist Richard Buckminster Fuller at Black Mountain College near Asheville, North Carolina. Taking inspiration from Fuller’s lectures on geometric models and his own research on Russian Constructivism, Snelson started studying 3-dimensional model and creating different sculptures, including the "X-shape" (Fig 1) his first tensegrity art piece, which he showed to Fuller in 1949. In 1955, R.Buckminster Fuller coined the term “Tensegrity”, which short for “Tensional - Integrity” and is commonly used nowadays to refer to this particular system. While Snelson, who continued with his research separately from Fuller, called the structure “floating compressions”.

Note (structural) Integrity is the ability of said structure to hold together under a load including its own weight, without breaking or deforming excessively

R.B. Fuller & Kenneth Snelson

Fig 1: “X-shape” 1948 by Kenneth Snelson

At the same time, but independently, Hungarian architect and engineer David Georges Emmerich, inspired by constructivist artist Karl Ioganson's structure (Fig 2), started to study similar tensegrity systems that ranged from simple to complex (Fig 3,4) However, he would call his works "structures tendues et autotendants", which could be translated to “Tensile and self-stressing structure” in English.

Fig 2: Ioganson’s structure that can be found in the exhibit

Fig 3,4: Emmerich’s models (1958-1960)

The Society of Young Artists 2nd exhibit,1921 Moscow, Russia

All three men patented the basic system under different names. ➔ Why are these types of structural systems widely referred to as “tensegrity” systems?

➢ ➢

Arch. Richard Buckminster Fuller (1) Arch. Engr. David Georges Emmerich (2)

➢

Sculptor Kenneth Duane Snelson (3)

Patent granted 1962 for “Tensile-Integrity structure” Patent granted 1964 for “Self-stressing construction” Patent granted 1965 for “Continuous tension, discontinuous compression structures”

Not only was Fuller’s “tensional integrity” the first successfully granted patent among the trio, he was an avid promoter of the concept of "tensional integrity". He provided a comprehensive definition of the term in his book Synergetics. Despite his writings being considered difficult to understand line by line, many of his concepts are applicable to real life structural systems.

(1)

(2)

Snelson & Emmerich

Tensegrit y

Fuller

(3)

Kenneth Snelson’s patent was the only one to display the structural generation of the structural system.

Comparison of the details of the three patents

DEFINITION "A tensegrity system is a system in a stable self-equilibrated state comprising a discontinuous set of compressed components inside a continuum of tensioned components."

"A tensegrity system is established when a set of discontinuous compressive components interacts with a set of continuous tensile components to define a stable volume in space".

Note ● ● ●

Self-equilibrated state is achieved with the balance between opposing component or forces in a system Compressed components don’t touch All components on the boundary should be tensioned components

"Inside" is the key word in the definition since it will allow us to separate two kinds of structural design: ➔

One which is a part of our constructive culture and based on compression as in the sustaining load effect, classified as tensegrity

➔

One based on tension as fundamental "support". E.g spokes on bicycle wheels.

Fundamental support

R.B. Fuller wheels analysis

how loads are distributed:

rte ive

rte

=> lighter load

➔

The structure adapts a slightly different shape as the load is applied to it.

quick math ;) 3x compressed components = s (in length) 9x tensioned components = c (in length) r=s/c=1.468^8, else: collapse or impossible to build.

Components: -

=> equilibrated (balanced) system:

TENSION/TRACTION Compression Compressed components: compression being discontinuous and a constant value - In use atypically: Note traction: a state of tension created by pulling forces steel, bamboo, wood. Result: A SELF-STRESS SYSTEM Tensioned components: tension being continuous ● has stiffness and a constant value - In use a typically: cable steel. ● less materials & solid spaces Nodes: connection between compressed components ● unaffected by external force and tensioned components

“Structure-Sculpture” 1921 by Karl Ioganson R.Emmerich named “elementary equilibrium” and regarded as first proto-tensegrity system

➔

“X-shape” 1949 by Kenneth Snelson R.B.Fuller regards as the first tensegrity structure

Both aren’t considered “tensegrity” by recent definitions - Ioganson’s structure is handled by means of an eighth unstressed cable, the whole being deformable, hence, doesn’t satisfy the “self-stressed” criteria. - In the case of X-shape, 2 strings are attached to the platform, rendering the tensioned components of the structure discontinuous

In 1968, Kenneth Snelson built the 26,5 meter tall “Needle Tower” with stainless steel trusses and aluminum cables, which soon became one of the most iconic examples of tensegrity. He would further work with tensegrity as an essential part of his sculptures until the end of his career

(1) Two pieces (2) Six#2 (3) Curve Throne

(4) “Needle Tower” 1968 (5) Kenneth Snelson working in his studio 1961 (6) Kenneth Snelson in front of “Soft Landing” 1982

While Snelson avoided physical and mathematical approaches of tensegrity, Fuller and Emmerich studied the different possible typologies of tensegrity, mainly spherical and one-dimensional systems: masts. They looked for possible applications of tensegrity to architecture and engineering.

Urban tensegrity 1958 / David Georges Emmerich

Three of Fuller’s basic structures (Tensegrity mast, Geodesic dome, octet truss) in Modern Museum, N.Y.

Fuller holding a 120-strut Geodesic Tensegrity Sphere

Shortly after viewing Snelson’s “X-shape” sculpture, Fuller studied several simple compositions, and produced a family of four Tensegrity masts with vertical side-faces of three, four, five and six each, respectively. He also discovered the 6-strut icosahedron (6-strut 20-face shape) Tensegrity system. ➔ The work was carried on by different people to create a hierarchy of tensegrity systems and fundamental laws of universal tensegrity structuring. 6-strut Icosahedron Tensegrity system

Tensegrity mast with 4 vertical side-faces

"Geodesic Tensegrity Dome" 1953 / R. B. Fuller

Despite having made great strides in the development of “Tensegrity”, R.B.Fuller never got to fulfill his dream of covering a whole city with a geodesic tensegrity dome. Despite his several attempts at the design, the final application of Tensegrity was not as successful as he thought it would be.

Moreover, Richard “Bucky” Fuller also believed that works of tensegrity were more natural than works of solely compression, as similar systems are found in the biomechanics of living creatures. “Nature relies on continuous tension to embrace islanded compression elements”

Continuous tension

Broadening the subject, Fuller would further philosophize that "[..] in the mechanical structuring of the universe, that compressive organisation is limited to the [..] spheres themselves, and that vaster structural integrity of the universe is maintained within the infinite limits of tensile stress principles only, which we identify as gravitational attraction.” _Designing a New Industry, 1945

Russian constructivism Movement

R.B.Fuller’s Energetic Synergetic Geometry lectures at Blackwood

“Universe tensionally coheres non-simultaneous events. Therefore, Universe is tensional integrity” _University of Michigan Mid Century Conference on Housing, 1949 Kenneth Snelson making the “X-shape”

Establishing the elementary tensegrity form “Universe is tensional integrity” _ R.B.Fuller

TYPOLOGIES

Spherical the cable set is always homeomorphic to a sphere.