FRANCISCO ALCAZAR FLUID STRUCTURES
You will all be familiar with the Thornton Heath Library we recently completed with FAT.....
which caused some controversy in the architectural press....
....asking what the structural engineer was thinking with the addition of this strut !
....In fact there is no structure, but rather architectural playfulness, with the architecture pretending to be structure.
which made me think about the expression of structure within architecture and the of my favourite creator of buildings ! materials....one we use
Frei Otto
Fluid has built its’ reputation on its innovative use of materials
...Shigero Ban is one of my favourite creators of buildings blurring the distinction between architect and engineer, and characterised as well by his choice of materials
picture of one of his buildings
Shigero Ban, born 1957 in Tokyo, Japan
“ I do not overtly express the structural elements, but rather they choose to express themselves” Shigeru Ban
Architect
Engineer
Experimenter
Inventor
Paper bridge France, half a mile from the Pont du Gard
... Perhaps most famous for his innovative use of paper
Which is perhaps not surpising considering his Japanese birth
Why paper?
A waste material Inexpensive Easy to recycle Low carbon footprint. Lightweight. Flexible (Earthquakes!)
Sensitive to changes in humidity Fire ‘New’ material, no regulations
Where?
He first used paper as a structural material in Alvar Alto Exhibition, Tokyo (1986)
Followed by the Paper Arbour at the Nagoya Design Expo89
The temporary structures continued with the Odawara Pavilion-East Gate. Here Ban used steel columns to support the roof, with paper tubes used both on the exterior and interior to withstand wind loading.
But Ban was looking to extend these theories beyond the temporary exhibition pavillion.
Developing world In 1992 Ban was commissioned by the UN to design temporary housing for more than two million Rwandans refugees escaping the ongoing genocide
Why use paper tubes? They addressed deforestation problems. Inexpensive. Unlike metals there is a low resale value, therefore less risk of theft or being sold off. Quick and simple to assemble. Easy to transport. It was possible to produce on site.
How?
Emergency Shelters, Byumba refugee Camp, Rwanda, 1995-1999
Japan 1995 Kobe earthquake
4 square meter cabin Ridge-beam construction Walls made out of paper tubes 108mm in diameter and 4mm thick. Self-adhesive, waterproof sponge tape between the paper tubes insured watertight fit. The plinth was constructed of borrowed beer crates filled with sandbags. The ceiling and roof, each made out of pvc
involving community in design
communal and religious buildings to sustain morale during reconstruction
involving community in construction
classrooms
Bhuj, India
each time the form of the temporary accommodation was designed to respond to local climate and social requirements
Ban first permanent tube structure ! First authorized use of paper tubes as e structural material in a permanent building. Designed with the explicit purpose of introducing tubes into Japanese building regulations, Ban created a dramatic show case for this new structural material.
10m x 10m base S-shaped arrangement of 108 tubes to form curving partitions. Only nine tubes are required to provide structural support. The remainder support lateral forces Each tube is screwed to cruciform wooden joists in the column bases... These are then anchored to the foundation. Creating a series of flexible interior and exterior spaces Narrow slots between the tubes allow light to enter this space and allow for a partial view between inside and outside
Tube paper testing.............
Experiment Date August 1990 Waseda University, Tokyo, Propose: Determine the long-term effect of creep of the paper tube under a constant axial load. The lengths were measured regularly over a period of one year. Five paper tubes Diameter 100 mm. Wall thickness 12.5mm Length 400mm Axial force 1000 kgf with the condition of one third of the loading
Results: Compressive strength of the paper was 103.2 Kgf/cm2(10.3N/mm2)
Paper tube compression test: Conclusion: A large percentage of dimensional change is caused by the relative humidity, and the dimensional changes due to creep are minimal.
Short-term strength Investigated through a compression test, and a bending test, and a single shear strength test.(wood to paper connection).
Paper tube compression test:
Results The specimen ends were markedly warped,as though twisted. Wrinkles were also apparent along the spiral winding edges of the nachine-rolled paper. The cause of this phenomenon is linked to the manufacturing process when machinerolled paper is wound up on a steel core.
Connections and flexibility
But... despite all the tests, some authorities are resistant to the use of paper. At the Hannover Expo 2000, Ban was allowed to use a paper structure but introducing an additional timber truss under the grid shell.
Japan Pavilion, Hannover Expo 2000 Ban consulted with Archited and Structural Engineer Frei Otto Ban propossed to otto a tunnel arch that measured 74 x25 x16 metres Three dimensional grid shell using long paper tubes without joints. This would avoid the cost of fabricating expensive wood joints. A grid shell of three-dimensional curved lines with indentations in the hight and width provided strong support against lateral forces. The tubes were fabricated in 20 metres lengths for transport and then connected using a wooden splice rather than a joint. Membrane material for the roof: Fireproof paper with glass-fiber reinforcement and a laminated fire proof film of polyethylene. (to meet Germany’s B2-grade fireproof requirements)
Structural and construction problems ! Preliminary strength tests of paper tubes were carried out by Buro Happold at Bath University When tests were proceeding, the basic structural design firmed up, and calculation undeway Test showed major structural defect. Large amount of creep in the paper tubes The paper tube were being tested, so their size could not be changed.
Further problems Hanover City Authority ordered new independent local Engineer Originally desin based of regulation for tempoary structure, (wind loading and ground friction coefficients) Now the design has to meet the same conditions as those applied for permanent buildings.
Solution: Originally Paper tube shell , ladders, and rafters were originally designed to be loosely connected and mobile Now the entire structure was to be rigid. To meet safety factors the section of rafters were enlarged and add unnecessary steel reinforcement. Push-up construction method was limited to two centimeters per day (20cm originally). This made impossible to meet the opning day. Roof paper membranes was required to be replaced with conventional PVC on the pretext that the pavilion moght become a terget for terrorists
Construction method
With the flexible joint system, the grid could be lifted up from below to form the grid shell. Ban also wanted the joint to be low tech material - Fabric or metal tapeThe tape will allow the angle between the tubes to open up in order to create a three-dimensional curve.
Otto also proposed a fixed timber frame of ladder arches and intersecting rafters. which would give further stiffness to the grid shell and allow the roof membrane to be attached/
Japan Pavilion Testing
Short term Axial Compression Test Long term Axial Compression Test Short term Bending Test Long term Bending Test Axial Compression test after assembly Applicably test of the baml proof Membrane
Short term Axial Compression Test
Short term Axial Compression Test
Long term Axial Compression Test
Axial Compression test after assembly
Applicably test of the damp Proof Membrane
Fire
Paper bridge France, half a mile from the Pont du Gard Shigeru’s cardboard-tube structure is strong enough to carry 20 people at the time and was open to the public for three more weeks, before being dismantled for the rainy season. Weighing 7.5 tonnes, the bridge is made from 281 cardboard tubes, each 11.5 centimeters across and 11.9 millimeters thick. The steps are recycled paper and plastic and the foundations wooden boxes packed with sand
