Bamboo building and culture 2000 - ...

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Bamboo Building
and Culture
By Darrel DeBoer and Karl Bareis
DDarrelD@aol.com
ã
Copyright 2000
The Architecture of Simon Velez
1
Simon Velez
, architect, CRA 2#9-54, Bogota Colombia captions written by Darrel DeBoer
Overview
This paper is intentionally sketchy about specifics
because of the many variables involved for someone
to try to replicate the work here: bamboo species,
age, curing method, wall thickness, bolt size &
material, mortar type, and especially design variables.
This work is very buildable and that by knowing
some of the details of the way Velez works, we might
begin applying some of his methods in the U.S.,
especially with smaller structures for which
permissions can more easily be received, and the
reputation of the material is not harmed by
improperly stressed structures. Larger structures
should involve Mr. Velez – there is no substitute for
experience.
importing the standard building materials of brick
and mortar.
The two critical breakthroughs Velez is able to teach
us relate to the bolt joinery with filled internodes and
the approach which uses no sheet goods (such as
plywood) to achieve extraordinary shear strength in
high wind and earthquake areas.
Velez is a graduate architect, from the University of
Colombia in Bogota. He has completed over 60
projects using a controlled palette of concrete,
bamboo, mangrove wood, woven palm mat lathing
(or expanded metal lath) and clay roof tile.
In Velez’ designs, roofs framed only with bamboo
are capable of cantilevers as long as 28’. Especially
intriguing when considering how much weight is in
his standard roofing of clay tile set in a full
mortarbed – he feels the heavy roof is needed to
combat the high winds, exactly the opposite of
conventional wisdom in the U.S. Clearly, we have
much to learn.
This view is up at a ceiling through the palm mat
lath.
Simon Velez works from Bogota, Colombia, South
America. As much of his work has been in very rural
areas for ranchers, he has been allowed to experiment
with the locally available materials due to a lack of a
regulating authority and the relative difficulty of
In the image above from the book,
Tropical
Bamboo
, one can see a rare simulation of what
The Architecture of Simon Velez
2
Europeans saw when they first came to this part of
the Andes: a continuous, feathery guadua forest.
While the botanists have classified several sub-species
of
Guadua
, Velez feels that many of the plants are the
same species, and it is the different climate and soil
type, which have great effect on plant characteristics
and pole quality. For example, Bogota is too cold: a
little too high in elevation (2600 meters) for
Guadua
to grow. His source of poles is in the lower
elevations outside the city, but there is a significant
structural difference between the 8-inch (20 cm.)
diameter coastal Guadua and the preferred 4-inch (10
cm.) which grows in poorer soil and slightly cooler
temperatures. When Velez works in neighboring
regions and countries, he brings a supply of the
favored bamboo with him. Learning the appropriate
microclimate for each strain of each specie is one of
our most arduous tasks in the U.S.
In the trusses at the base, the wooden poles are
joined in the same manner as the roof bamboos.
Velez has developed a very interesting model for
building experimental structures. He builds only
with his own well-trained crew of workers, so he is
able to constantly draw upon past successes and
failures in detailing. He intentionally keeps
drawings simple, usually freehand on single sheets
of 8x11 graph paper. Full-sized details are mocked
up on-site or are referenced from the memories of
past jobs.
The species of timber bamboo preferred by Velez,
Guadua Angustifolia
, achieves full height (100 feet +)
in 2 months, adding only strength for the next 3 years
at which time it is harvested. It is reputed to be the
only species of bamboo capable of having nails
driven into the culms without splitting. However, it
doesn’t tolerate frost well and will only grow in the
far southern U.S. states. He was impressed with the
strength of our
Phyllostachys
varieties, though
nobody has tried these kinds of spans here.
In traveling with Velez, I saw numerous original
drawings sprinkled over the jobsites. Because he is
free of the contentious architect/contractor
The Architecture of Simon Velez
3
relationship, his drawings are done completely to
serve the building.
To Velez, the building is all that matters. If
absolutely required, the client must obtain Building
Permits, but he won’t help. Velez views every
moment’s delay as an impediment to the most
important task of building. Detailed drawings are
seen as another delay. The client is shown very few
drawings. What is important is that the client
maintains absolute faith in his ability to execute the
work.
All joinery is done with bolts, he never uses tying
because the bamboo shrinks and the joints become
slack. Sometimes the bolts are reinforced with
straps where the forces are the greatest.
He keeps that by making drawings that embody the
intent of the structure.
His experiments have made his buildings exercises
in statics - keeping most of the members in tension,
but where compression and shear exist at the bolted
joints, he fills the internode with mortar to keep the
bolts from crushing the walls of the bamboo.
Most useful are the section views which are usually
repeated through the whole building.
With many of his center-bearing trusses (posts close
to the middle of the truss), the point of great strain
is the very ridge. Across the ridge Velez puts a steel
strap which is bolted through the bamboo on either
side. In stress tests, it is this strap or the bolts
which fail. He has yet to see the bamboo fail.
The clearest concept to be seen in his drawings is the
necessity for balance. These cantilevers are very
large, but maintain an obvious center of gravity over
the support.
The Architecture of Simon Velez
4
The only substantial publication of his work is a
book published by Rizzoli call
Tropical Bamboo,
now out of print. If you can find a copy at a library,
it is the best source for giving a context to Velez’
work. In it, Velez wrote, “At the beginning of this
century, two successive fires in Manizales razed only
the upper-class houses. The rebuilding of the city
center and cathedral saw the first use of concrete and
marked the demise of the use of bamboo or any kind
of wood. Ever since, in Colombia, bamboo and
wood have been synonymous for slums and misery.”
When he does a structure that he considers
experimental, he charges little and tests at full scale.
Clients don’t let him test those structures to failure
like he wants, they live in them.
Pound for pound, the
Guadua
has a better tensile
strength than steel. The structural strategy is to
design trusses which take advantage of the tensile
strength of bamboo, then, where the inevitable shear
and compression loads exist, the internodes, through
which bolts are placed, are filled with concrete.
These images show that bamboo used as bamboo,
taking advantage of its unique qualities is capable of
so much more than solid wood. We can begin to
transition to the use of structural bamboo in this
country by building structures half as big as these and
still feel confident in the integrity of the material.
A passive solar, bamboo-framed house where the
mortar and plaster is put to good use as thermal
storage.
Velez believes traditional joints are unreliable. If
strutures are to be plastered, organic ropes can’t be
cinched up in 3 months when the bamboo shrinks or
in 2 years when the humidity rots the rope.
Guadua
is so strong and will definitely continue to shrink
and swell that it will overwhelm any other binding
material.
It is important to note that in Colombia, the wealthy
are now accepting a material that is inexpensive and
associated with poor people.
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