Friday, January 17, 2014.
San Antonio, Texas

 Minimal Surface Blog Entry (corrected January 24, 2014).

Origin of the Term Minimal Surface

Before Frei Otto’s comprehensive investigation on minimal surface structures, the main precedent we had were:
1. The temporary or commercial buildings made for the circus;
2. The tents used in the dessert either in Africa or Middle East, or
3. The clearance sale tents built at parking lots of numerous department stores or car dealerships to showcase their excess inventory.

Example of a circus tent

Example of a circus tent

Bedouin tent in Egypt

Bedouin tent in Egypt

Car Dealership tent

Car Dealership tent

Soap film is considered to be a minimal surface. When the film attaches to a frame – it takes a particular shape when all of the forces that exert on it are in equilibrium. When the soap film is in equilibrium – it displays stability and strength.


It is light, making it easy to transport or to fabricate.

It is safe for once the mesh is stretched and anchored; a person can walk on top of it.

It is economical. It may cost less to build a membrane structure, than to build a stadium with reinforced concrete walls. You don’t have to build it on site – it could be built off site at an economical workshop.

It can be assembled or dismantled quickly, or be left permanently. The Federal Gardens from Frei Otto at Kassel (Cologne, Germany) date back from 1952 and it is still standing.

Federal Gardens, Cologne Germany

Federal Gardens, Cologne Germany

When not needed, this type of structure could be dismantled and used at another location, or recycled.


Minimum Surface construction has many shapes:

1. Hup tents
2. Peak tents
3. 4 point tent
4. Double curve
5. Parabolic
6. Hyperbolic
7. Single curve


These structures can be made of:

1. Wood
2. Cables
3. Steel mesh
4. Steel skin
5. Steel masts
6. Plastic skin
7. Canvas
8. Concrete anchors to tie the cables at the end at about 120 degrees from the horizon.

The Evolution of Minimum Surface construction through the years

Tents or membrane structures have evolved over time.

1. Nomadic tents in the Middle East
2. The Native American Conical Tepee
3. The Central Asian Yurt





These structures were made of diverse compositions such as animal skins, or diverse textiles.

The fabric used by the Bedouin tribes in Syria, is woven from goats’ hair. When it rains the weave contracts and doesn’t let the water in. In the heat of the summer the outside of the tent feels very hot to the touch while the inside remains blissfully cool. In the winter when it is cold outside with a small fire inside the reverse is true, and the tent stays warm and cozy. (El Dohous Village, Bedouin camp web site, contact page).

The very first developed membrane roof was erected in Russia in 1896. It was called the Shukov Rotunda, and it opened the All of Russia Exhibit of 1896.

Zhukov Rotonda 1896

Zhukov Rotonda 1896

Nowadays, a minimum surface structure is still thin and flexible and carries loads primarily through tensile stresses. In other words, these membranes are pre-stressed by external applied forces and they hold their strength during pre-calculated load conditions. (Beeson, Summer 2013).

In 1995, The Denver International Airport was built, introducing an airport terminal roofed by a white membrane stretched from steel masts. Incidentally, they have done this type of airport construction in numerous airports around the world. The mesh resists winds and snow since they are at a high pitch angle. (Beeson, Summer 2013).

Denver Airport minimal surface roof

Denver Airport minimal surface roof

Other modern examples are the newly restored OAKA Olympic Stadium (aka Spiridon Louis) in Athens, Greece. (Beeson, Summer 2013).

Oaka Stadium - Athens, Greece

Oaka Stadium – Athens, Greece


Iconoclastic is the term assigned to minimal structures because they get forces exerted laterally and vertically giving the structure its strength and stability. (Nerdinger, pages 18-22)


The shape of the minimal structures is usually hyperbolic, parabolic, square, circular, semicircular, maybe cloverleaf shaped due to its characteristic 120-degree angle where the soap film becomes stable.


Our objective is to successfully design a minimal structure, a transitional structure, that will connect the old McNay Museum to its new wing, providing a path, shelter, maybe a pause from building to building, and a a connection with nature.

We plan to use the shapes Frei Otto used during this physics soap film experiments: hyperbolic, round, parabolic, circular, triangular, square, prism shaped geometry, as well as tension and compression to give the structure resistance to the wind, anticipated load support, resistance to rain and snow, and also to make it aesthetic.


A Minimum structure can be built using tension and compression, tensile material or fabric, and several anchor support. We plan simulate in our model the tensile structures of today, but at a lower scale making it affordable.

Model Materials

6 oz. jar of Glycerin
24 oz. of Walgreen’s Orange Liquid Dish Soap
66 oz. Walgreen’s Distilled Water

(As inspired by Frei Otto’s soap recipe.) (Nerdinger, page 19)

Rubbermaid gallon container
Green plastic mixing bowl
Copper wire
1/16th of an inch wire roll (picture hanging wire)
18-gauge copper wire
1mm elastic cord (Bead Landing Brand)
1mm transparent elastic cord (Stretch Magic Brand)
18 w to 30 w soldering device
Soldering Wire
A ruler
Masking tape

Our Experiment:

On the first day after our initial class, January 13, 2014, we studied carefully pages 18 through 22 of Frei Otto’s complete works, and we did about 5 to 6 models.

We mixed our soap recipe in an empty Rubbermaid gallon container. Then poured the mixture in green plastic mixing bowl that had more space for dipping our models.

We began soldering copper wire together along with silver soldering wire making a square, a triangle and a circle model. After the models cooled down, we dipped them in the soap, and we were able to capture the soap film in color using a portable Canon digital camera and a drafting light.

Afterwards, we twisted and extruded from the square, triangle and circle, more abstract shapes.

Soap film experiment 1

Soap film experiment 1

Triangular soap film

Triangular soap film 2

Extruded TriangleSoap Film 3

Extruded TriangleSoap Film 3

Circular Soap Film 4

Circular Soap Film 4

After our experiments, we learned the need to mount our models in either paper or a waterproof base to support them and to give them a cleaner form.

This approach would give us the minimal, simple and natural distinguished look achieved in Frei Otto’s work; for Frei Otto’s work uses the minimum amount of material in order to provide the maximum amount of flexibility. (Glueck, page 19).

When the material is minimal, it resembles nature itself and it is also less disruptive to nature. The soap bubbles do attach together at an angle of 120 degrees illustrating the equilibrium or balance of tension and compression forces. (Nerdinger, page 19 – 22).

Later, We made more models (circular, square, and triangular) with the 18-gauge copper wire, and by soldering together pieces while being taped to a rigid piece of cardboard producing a smoother shape.

By Friday evening, July 17, 2014, we had explored more materials such as Plexiglas, which was later cut, with 1/16-inch holes cut in the middle in order to provide an anchor for our material.

Through the 1/16th of an inch holes, we secured the 1/16th inch wire roll, to its wall and base. This worked very well, for the Plexiglas provided the support we wanted and we could adjust the geometry of the wire in different ways replicating some of the shapes Frei Otto created. (Nerdinger, page 19 – 22).

We may explore different kinds of transparent, flexible and stretchable strings made which also resemble tension construction and would provide a transparent boundary for the soap film.

Andres Mulet    Aleksandr Mikhailov    Troy O’Connor

(The Minimal Surfaces Group).


Bill Addis, 2005. Frei otto: Complete works. Construction History 21, 115, (accessed January 17, 2014).

Edward Allen, Fundamental of Building Construction: Materials and Methods 4th Ed. John Wiley and Sons Hoboken New Jersey 2004 (page 424).

Bedouin Camp – El Dohous Village – Desert Life (accessed Jan 24, 2014).

Sadet Beeson, Ph. D, Lecture on Membrane Structures, Building Technology 3 Summer Semester 2013- University of Texas at San Antonio June 5, 2012.

Frei Otto in Conversation with the Emergence and Design Group: Architectural design, ISSN 0003-8504, Nº. 3, 2004, pages. 18-25.

GRACE GLUECK. 1971. Art: Frei Otto’s ‘minimal structures’ subject of display here. New York Times (1923-Current file) 1971. (accessed January 17, 2014).

Guillermo José Jacobo, Ejemplo Diseño estructural experimental en arquitectura como metodología de diseño arquitectónico. -: Universidad del Nordeste, Facultad de Arquitectura y Urbanismo, Resistencia, Provincia de Corrientes y del Chaco – Argentina. (accessed Jan 24, 2014).

Karl L. King and the Sells-Floto & Buffalo Bill Wild West Combined Shows Band 1914 to 1916 (accessed Jan 14, 2014).
Achim Menges. 2006. Michael Hensel; Frei Otto. Architectural Design 76, (2): 78-87, (accessed January 17, 2014).

Winfried Nerdinger, Frei Otto, and Technische Universität München. Architekturmuseum. 2005
Frei Otto: Complete works: Lightweight construction, natural design Birkhäuser, (accessed January 17, 2014).

Darryl Ohlenbusch , M. Arch, Lecture on Modern Mexican Architecture – Spanish Architect Felix Candela History of Modern, ARC 6973 Section 903 – University of Texas at San Antonio April 2, 2013.

Darryl Ohlenbusch , M. Arch, Lecture on Modern Japanese Architecture – Kenzo Tenge History of Modern, ARC 6973 Section 903 – University of Texas at San Antonio April 11, 2013.

Frei Otto1969. Design quarterly (74/75): 25-27; (accessed January 17, 2014).

Positioning of Olympic Stadium Roof (accessed Jan 24, 2014).

Train Model Circus Tent from a Hobby Shop (accessed Jan 24, 2014).

Tokyo National Olympic Gymnasium by Kenzo Tange (Kenzo Tange – Olympic Stadium of Tokyo) (It uses minimal surfaces, tension and compression) accessed Jan 24, 2014).

Torsione primaria e torsione secondaria: differenze ed esempi: Article about The Oaka Stadium in Athens – Membrane Construction by Structural Engineer Onorio Francisco Salvatore (accessed June 5, 2012, and Jan 24, 2014).

William J. Curtis, Modern Architecture since 1900, 3rd edition (Upper Saddle River, NJ: Prentice Hall, 1996).

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