1. Bamboo as a Construction Material
With emphasis on building elements
Presented bySethu Sai KrishnaNithin Shenoy T Karan Shiyal
Bharath ChandraSai Praveen
Anudeep Raviteja -
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2. INTRODUCTION
Bamboo is a versatile, strong, renewable and environment
friendly material.
It is exceedingly strong for its weight and can be used both
structurally and as a finish material.
Bamboo is recognized as one of the most important nontimber forest resources because of the high socio-economic
benefits from bamboo based products.
Bamboo can be recombined into useful products and elements
such as flooring, ceiling, walls, partition walls, trusses, domes,
etc.
3. OBJECTIVES
1. To study important characteristics of bamboo
as it significantly contributes to the structural
soundness and durability of the houses.
2. To explore and study the modern construction
techniques of bamboo used for the construction
of building elements.
4. BAMBOO IN BUILDINGS
Bamboo has good engineering properties and it is a
feasible substitute for other materials for housing and
construction sector.
Bamboo has high tensile strength, very good strength to
weight ratio. It can be easily worked upon by simple tools.
It can resist forces created by high velocity wind and
earthquake.
Bamboo and components made of bamboo are
environment friendly, energy efficient and cost effective.
5. SELECTION OF BAMBOO SPECIES
It should be available in large quantity from near by
plantations.
Transportation should be economic.
It should have good engineering properties.
Considering these factors, Dendrocalamus Strictus is
selected as it is available in abundance in the region and has
good engineering properties to be used as a construction
material.
6. BAMBOO SIZES
Bamboo sizes are generally specified by minimum diameter, wall
thickness, and length.
Column – 80-100mm dia
Wall thickness – 10-12mm dia
Bamboo strips for infill panels – 18-20mm wide, 8-10mm thick
7. BAMBOO: A BUILDING SYSTEM
A building system in which bamboo comprises of various
elements and fulfils the main structural role.
Round bamboo columns and trussed rafters act as the main load
bearing element.
Composite bamboo grid/cement mortar infill panels act as shear
walls to resist wind and seismic forces. The system comprises of –
FOUNDATION: individual column footings.
COLUMNS: bamboo culms set in/on concrete footing.
WALL INFILL: a grid of split bamboo covered in wire mesh and
cement mortar.
FLOOR: raised by 2-3 brick courses, filled with rubble and screeded.
ROOF STRUCTURE: bamboo rafters or trusses supporting bamboo
purlins. Corrugated bamboo mat board for roof covering.
DOORS AND WINDOWS: bamboo mat board shutters.
8. BAMBOO PROTECTION
Bamboo is susceptible to attack by insects and
fungi, and its life could be as low as one year when it is in
ground contact.
PROTECTION BY DESIGN
1. Large roof overhangs prevent
direct wetting of walls in heavy
rains.
2.
Drainage channels/gutters to
discharge water at a safe
distance from the building.
3.
The risk of flooring can be
reduced by building on a
slightly sloping site and using
raised masonry or concrete
footings.
9. PROTECTION BY DESIGN
1. Raising bamboo columns
or wall panels clear of the
ground reduces risk of
termite infestation.
2. Termite shield formed out
of galvanized steel or
aluminum sheet between
footing and walls.
3. Hollow culms should be
plugged.
4. Cavity walls should be
avoided.
10. PROTECTION BY PRESERVATION
DIP DIFFUSION METHOD
Bamboo culms are prepared to size and
submerged in Borax/Boric Acid solution which is
a water soluble preservative for several days. The
preservative enters the culm through ends and
holes drilled in internodes.
This process is suitable for both green and dry
bamboo.
11. HOT AND COLD METHOD
The bamboo to be treated is submerged in a tank
of preservative that is directly heated by fire
after being maintained at a constant temperature
for a period, the tank is allowed to cool.
During the cooling process, the preservative is
drawn into the bamboo.
The hot and cold method can be used for
green or dry bamboo culms with either Boron or
Creosote.
12. AN OVERVIEW
STAGES
1. Treated bamboo columns are in/on steel shoes or individual
concrete footings. The plinth is built up to floor level using
bricks, stones.
2.
Timber wall plate is fixed to the tops of the columns.
Treated bamboo strips are wired to other and to steel dowels
passing through the column.
3.
The grid is covered in chicken mesh. Cement plaster is done
on both sides of the grid to a finished thickness of 50-60mm.
13. FOUNDATION AND FLOOR DETAILS
1. Where the column is set in the footing, it should be
(400x400x400)mm deep. Where the column is set on
the footing using a cast-in steel shoe, the footing
should be (400x400x400)mm deep.
2.
The floor is raised by 200-400mm above the ground
level, using bricks, concrete blocks/stones, to define
plinth perimeter. It is filled with compacted earth,
topped with half bricks and screeded with 20mm of
cement mortar.
COLUMNS
14. 1. Treated bamboo culms, 80-100mm in dia, provide
basic load bearing framework for the building. The
columns are spaced at intervals of 1.2m.
2.
Timber wall plate, 100x38mm in cross section is
fixed to the columns by screwing or skew-nailing
into wooden plugs.
15. WALL INFILL PANEL
1. The wall infill comprises
a grid of split bamboo,
20x10mm, tied together at
150mm spacing using
mild steel binding wire,
and set between the
columns.
2.
Chicken mesh is fixed on
the outer face of the grid.
3.
Cement plaster is applied
on both sides to a finished
thickness of 50mm.
16. ROOF
1. The roof comprises bamboo trusses at 1.2m
spacing, located over the columns.
2. The 3mm BMCS are laid and fixed using J-bolts
and bitumen washers.
17. FABRICATION OF STRUCTURAL MEMBER
S
All structural members like columns, beams, trusses, purlins are pre-fabricated
and made of bamboo.
Bamboo Mat Corrugated Sheet (BMCS), Bamboo Mat Board door and window
frames and panels are the special features of this housing project.
COLUMNS
After completing conventional plinth,
columns are erected. For a single dwelling 6
columns are required.
Bamboo column
cap and gusset
plate made out of
bamboo mats
Pre-fabricated
Bamboo column
with cross bracings
Column ready for erection
18. F A B RI C A T I O N O F S T RU C T U RA L M E M B E RS
COLUMNS
Prefabricated bamboo columns
are aligned and erected over concrete
pedestal, to avoid ground contact.
Water repellent coat is applied
over the part of column, which is
embedded in concrete in order to
minimize water absorption by bamboo
from 1:2:4 concrete at the time of fixing
into concrete.
Column is embedded in PCC
1:2:4 up to +750mm GL
W section with
all
foundation details
19. F A B RI C A T I O N O F S T RU C T U RA L M E M B E R
COLUMNS
Column consists of 4 bamboos
interconnected with cross bracings.
Cross bracings also reduce effective
length of column and helps in
increasing load carrying capacity of
column.
Bamboo Brackets
supporting the roof
Bamboo screwed
to avoid
splitting
Column details
20. F A B RI C A T I O N O F S T RU C T U RA L M E M B E RS
BEAMS
Beam ready for erection
Beam resting on column and
supporting BMCS
For a single dwelling 4 beams are
provided. Single beam consist of 4 long
bamboos with cross bracings. Additional
bamboos are provided to facilitate the
arrangements of shelves and lofts.
4 bamboos are convenient to place
column cap, fix beam and truss over cap.
Column, Truss and Beam junction
21. F A B RI C A T I O N O F S T RU C T U RA L M E M B E RS
TRUSS
Bamboo pre-fabricated
truss supporting
BMCS and purlins.
Also seen, bamboo
mats used in upper
1/ area of wall for
4th
light and ventilation.
Truss ready for erection
3 trusses are required for a single dwelling. Queen post trusses are prefabricated as per drawings and specifications. Fabrication of truss member is
comparatively complicated. Single bamboo is sufficient as a structural member of a
truss though the double member is provided considering aesthetics and
convenience for joinery.
22. F A B RI C A T I O N O F S T RU C T U RA L M E M B E RS
COMPOSITE W
ALL
Composite wall consists of –
Bamboo mat as a filler.
Wire mesh fixed over mat surface.
Plaster in cement mortar 1:6 on both
sides.
Brick masonry in cement mortar 1:6
is provided from plinth level up to 300mm
height and composite wall starts at this
level.
Bamboo mat consists of
half split bamboos placed
vertically at 300mm c/
c.
Lower end of half split
bamboo is inserted in
brick masonry. Upper end
is fixed to the tie beams
and extended up to inner
surface of BMCS.
Plan
Composite wall detail
23. F A B RI C A T I O N O F S T RU C T U RA L M E M B E RS
COMPOSITE W
ALL
Bamboo columns are covered with bamboo strips
in such a way that junction between wall panel and
columns will be free from gaps.
Columns are covered separately to facilitate
alteration and modifications without damaging the
composite wall panel.
Wire mesh is fixed over mat surface, as stretched
as possible and 20mm thick cement plaster in cement
mortar 1:4 is applied over mat surfaces on both sides.
Total thickness of Composite wall is 75mm which
provides good temperature insulation.
Column separate bamboo
mat
Horizontal strips woven
around half split bamboo
24. M E RI T S O F B A M B O O I N B U I L DI N G
1. AFFORDABILITY
Foundations are minimized, wall panels are non-load bearing and can
be reduced in thickness, and the basic components (bamboo, wire, bolts,
chicken mesh) are inexpensive.
2. SUSTAINABILITY AND ENVIRONMENTAL
IMPACT Bamboo is a renewable resource with a short rotation period and can
be grown on degraded land. It is treated using environment-friendly
preservatives. The use of high energy embodied materials (cement, steel) is
minimized.
3. CULTURAL ACCEPTABILITY
The system offers traditional materials in a modern engineering
context.
4. DURABILITY AND SAFETY
All bamboo components are treated with safe preservatives to give
extended life, the structure is engineered to resist wind and seismic forces, and
other imposed loads.
25. M E RI T S O F B A M BO O I N B U I L DI N G
5. IMPROVED JOINTING TECHNIQUES
Nailing is eliminated; wiring, bolting and strapping provide
positive connections.
6. MODULAR CONSTRUCTION
Bamboo is suited to both prefabrication and fabrication in situ: All
components are designed to be prefabricated (ex-infill grids, roof trusses) or
prepared on site.
7. EASE OF ASSEMBLY
Only basic carpentry, masonry tools and skills are required to
undertake construction.
26. DE M E RI T S O F B A M B O O I N B U I L DI N G
1. Bamboo lacks natural durability which contributes to the view of
bamboo as a temporary material.
2. Bamboo is susceptible to attack by insects and fungi and its service life
could be as low as one year when it is in ground contact.
3. Bamboo cannot span very large structures and high rise buildings cannot
be made from it.
4. Bamboo Mat Corrugated Sheets absorbs moisture more as compared
with asbestos and plastic corrugated sheets. This may influence its
durability in external utilization.
27. RE C O M M E N DA T I O N S
Cashew nut oil should be applied over exposed bamboo regularly, to
improve the life and service of bamboo members and aesthetic also.
To make proper joints, bamboo should be
screwed and not nailed to avoid splitting of
bamboo.
Bamboo screwed to
avoid splitting
After fabrication, culms should be closed
from both sides with proper infill material, to
avoid insects and termites enter it.
Culms closed from both
sides with suitable material
28. REFERENCE
NMBA - National Mission on Bamboo Application, Delhi
- The Bamboo book (Training manual)
- Building with Bamboo (Training manual)
http://www.bambootech.org/subsubtop.asp?subsubid=110&subid=42&sname=usage
Internet
www.villagevolunteers.org/wp-content/uploads/2011/06/Bamboo-House-Building
CIBART -Centre for Indian Bamboo Resource and Technology
INBAR –International Network for Bamboo and Rattan