The bamboo supply imported from Colombia consisted in a container with four hundreds Guadua poles, 9 m long. The poles had been treated still in Colombia in a smoke-chamber, a preservation technique originally used in Japan and rather recently adopted by some Colombian Guadua suppliers.
All through the building process we have become more and more aware of the qualities and limits of bamboo building and of bamboo as a building material, of the importance of the harvesting methods, of the poles drying process, of the protection measures and preservation treatments and of how these features can affect the static performances of the building that was being constructed.
At present we are still unfortunately not sure whether the smoking process carried out on the bamboo that we have imported is effective in the long run and after a thorough investigation and the precious help of experts, we can say that if the smoking has to be the preservation method applied, then it should be done in vertical chambers and for a convenient period of time. A smoking process on horizontal culms, for too short and on not properly or not enough dried culms seems to be really non sufficient.

The cost per sq. m. of the Vergiate Pavilion was € 100 (around 120 US$), including materials and tools (labour costs excluded). If the same building was done in timber, its large cross section would require the use of laminated wood, therefore - in terms of mere money - we can state that a bamboo construction of this size and shape can be remarkably cheaper than an equivalent  one in timber, not to mention the environmental costs involved in the life-cycle of laminated wood which are higher than the environmental costs due to the bamboo transportation from the Tropics. Regarding labour costs, any generalization of the Vergiate case would be obviously inappropriate.

Our Pavilion, as any permanent public building in Italy, had to comply with the current regulations regarding structural stability and safety measures, including protection against biodegradation, fire, wind, earthquakes and snow resistance.
For bamboo constructions, the testing protocols and models are not yet stated. An international building code for bamboo structural design is under discussion by the ISO/TC 165/WG9 Committee based on the precious work of Prof. J. Janssen. 

In order to obtain the certification of static suitability of the Vergiate Pavilion according to the load conditions stated by the Decreto Ministeriale of 16.01.1996, a preliminary static calculation was made using the available data regarding the mechanical features of Guadua Angustifolia obtained from the ZERI experience in Hanover, on a model of the actual structure.
The geometric model was made of a cross portion of the building, 2 m large and containing all the typical and recursive elements. The model was three-dimensional, representing the buttress and a part of the main beam.

The loading tests protocol was provided by the Studio De Miranda Associati (Milano, Italy) while the laboratory tests on bamboo specimen to determine the physical and mechanical properties were carried out by the Istituto Masini (Rho, Italy).

The bamboo mechanical properties used in the calculation model are as reported in Table 1.

All the structural elements of the model were constituted by culms whose outside diameter was 10 cm and whose mean wall-thickness was 1/10 of the diameter. 
On top of its own weights, the forces acting on the building considered in the calculation were:

1.  vertical forces (snow on the whole roof)
2.  vertical forces (snow on half of the roof)
3.  horizontal forces (wind) in the frame plane (crossing the fabric)
4.  horizontal force (wind) perpendicular to the frame plane (along the main axis of the fabric)

The vertical forces, including permanent and accidental weights, were 1,30 kN/m2 and the horizontal forces were 0,25 kN/m2.

The calculation results revealed critical slimness values in some of the beams and exceeding tensions in the roof beams. This is why we decided to carry out some laboratory tests in order to assess the real mechanical properties of the Guadua used. The pressure and traction resistances were quite similar to the ones of the ZERI Pavilion with the exception of the elasticity module whose value was slightly higher than 1/3!

On the basis of the resistance features revealed by the laboratory results, a series of weight tests was carried out. The static test inspection took place on the 8th of July 2003. The loads were hung from the ridge of the one truss, amongst the 15 built, presenting the highest number of irregularities, such as dimensions of bamboo elements, deviations from the straight axis and differences in internodal lenghts, wall thickness, etc. The actual weight test consisted in measuring the deformations of that particular truss and of the two adjacent ones.

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