Use of Small Diameter Timber Resources for Light Timber
Frame Constructions, Emergency Shelters, Small Industrial
Buildings, Furniture and Assorted Wood Products
by
Carl A. Eckelnam
Eva Haviarova
Huseyin Akcey
Department of Forestry
and Natural Resource
Purdue University
United States
Research Outcomes
• We have shown that low cost,
durable furniture and light timber
frame buildings can be constructed
from essentially waste wood
materials using only the simplest
manufacturing techniques with
round mortise and tenon joint
construction
• Shortages of school furniture and
building frames can be eliminated
with little environmental impact
• While promoting rural community
development
Presentation Outline
• Available material resources
• School furniture products development and
production
• Light timber frame building construction and use
• Alternative connectors and joinery research
Small-Diameter Trees
• Many forest stands
worldwide are over-stocked
with small-diameter trees
• They should be selectively
thinned
• More extensive use of
existing timber resources
would extend supplies,
reduce waste and improve
the forest health
Plantation
Thinnings
• Plantations need to be
thinned to optimize
tree growth
• Presently, plantation
thinnings have
insufficient market
value to justify their
removal
Residue Material from Tree Plantations
• Large quantities of
potentially useful but
largely unused wood
materials presently
exist and are available
for conversion into
value-added wood
products
Potential Products
• Structural applications offer a
high-potential value-added
market for small-diameter
stems
• Furniture (especially school
furniture) is another valuable
product, particularly in
under-developed countries
School Furniture
Costa Rica
Costa Rica
Traditional Joinery - Square Mortise and Tenon Joint
Costa Rica
New Joinery - Round Mortise and Tenon Joint
Round Mortise and Tenon Manufacturing
Solid Wood Construction
• Combination
of strong and
weak solid
wood species
• Round
mortise and
tenon joints
• Shrink and
swell jointing
method
Performance Testing
• Direct evaluation of the
prototype strength and
durability
• Identification of the
areas of possible
improvement
Manufacturing Process
Structure
Diagram
for Chair
Manufacturing Process
Structure
Diagram
for Table
Process
Analysis
– Material
Flow
Pilot Study – Summary
„
Product Design
„
Manufacturing System
„
Finished Product
„
Delivery
Pilot Study Results – Costa Rica
Production at Institute of Technology Costa Rica
Costa Rican workers were trained to
understand the principles of new
construction
Ergonomic Studies and Technology Transfer in C.R.
school
furniture
placed
around
of the
country
Success Stories – Jamaica
Success Stories – Uganda
The
Humble
Way
(Orphanage)
Success Stories – Uganda
School Furniture Need for Afghanistan
School Furniture Graveyards:
- A very common sight at Afghan schools
- Only year or two old poorly made furniture
given to schools by various aid agencies
School Furniture Need for Afghanistan
2002 – 6,400 desks and chairs were provided
2005 – 153,600 desks and chairs are needed
Light Timber Frame Construction
Need for Housing in Developing Countries (Africa)
Round Mortise and Tenon Construction
• Provide simple and straightforward method of
constructing building frames
• Differs essentially only in the geometry compared to
rectangular mortise and tenon construction
• Tenons are efficient load carriers and are highly
resistant to cyclic loading in bending
• Basic strength characteristics and suitability for use in
building frame construction was thoroughly studied
Horizontal Drill Press
• A simple low cost
horizontal drill press
was built to machine
tenons
Horizontal Drill Press
• Alternative horizontal
drill press was
developed in Costa
Rica
Machining of Members
• Tenons for the frame are cut
with 2, 3, 4-inch diameter by
12-inch deep hole saws
produced by a commercial
supplier
• The excess material was
removed from around the
tenon with a miter saw
• Mortises were drilled in the
members with 2, 3, 4-inch
diameter Forstner bits
Parts Fabrication
• Material was first cut to
size
• Tenons were cut on the
ends of the members
• Mortises were drilled
into the sides of the
members
• Standardized parts that
can be incorporated into
modular construction
Frame Construction
• Corner posts, wall
studs, and doorpost
tenons were inserted
into the corresponding
sill mortises
• Joints were pinned to
the sills
Frame Construction
• The ridge rafter beam
along with the side rafter
plates were extended in
order to provide the fly
rafters needed for an
overhang
• The walls and roof were
sheathed with standard
grades of plywood
Construction Benefits
• Easy and rapid
assembly from a stock
of standardized parts
• Disassembly took 15
min, and re-assembly
40 min
• Costly connectors are
eliminated
• Basic or no tools are
necessary
• Unskilled labor can be
used to erect a frame
• High resistance to
vertical and lateral
loading (hurricanes and
earthquakes)
Test Models
• Standardized parts can be easily incorporated into
modular constructions to serve a wide variety of needs:
backyard storage sheds, shelters, farm building, light
industrial buildings, multipurpose buildings-- in both
developed and under-developed countries
Modular Constructions – Rangers Huts
• Costa Rica
Modular Constructions – Exhibit building
Cottage Industry
Alternative Connectors and Joinery
Joint Strength Tests
- Withdrawal
Resistance
- Bending
Resistance
- Shear Test
Potential Timber Frame Connectors
•
Through-bolt with dowel nut
Through-Bolt with Cross Pipe
and Nut Construction
Through-Bolt with Cross Pipe and Nut Construction
Tension Specimens – Nut Located Inside of Cross Pipe
Avg. strength is 13,570 lbs in for 3-3/4 in-sq Yellow poplar.
Through-Bolt with Cross Pipe and Nut Construction
Tension Specimens – Nut Located on the Outside of the Cross Pipe
Avg. strength is 11,250 lbs in for 3-3/4 in-sq Yellow poplar.
Through-Bolt with Cross Pipe and Nut Construction
Tension Specimens Reinforced with Cross Bolts
Avg. strength is 19,270 lbs in for 1-1/4 pipe 3-3/4 in-sq Yellow poplar.
Avg. strength is 23,160 lbs in for 1-1/2 pipe 3-3/4 in-sq Yellow poplar.
Through-Bolt with Cross Pipe and Nut Construction
Tension Specimens Reinforced with Washers
Avg. strength is 19,950 lbs in for 3-3/4 in-sq Yellow poplar.
Potential Timber Frame Connectors
Tension Specimens Reinforced with Pipe Inserts
Avg. strength is 22,890 lbs in for 5-1/4 in-sq Yellow poplar.
Through-Bolt with Cross Pipe and Nut Construction
Round Tension Specimens Reinforced with Hoop (1/4 in Rod)
Avg. strength without reinforcement - 7,238 lbs
Avg. strength with reinforcement - 17,740 lbs
Truss Applications
Round mortise and tenon and
trough-bolt with cross pipe
and nut connections in truss
applications
Foot Bridges
Summary
•
•
•
•
•
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Areas of interest: developing areas of the world, rural community
with small businesses opportunities, indigenous habitats
Designs attributes: simple, very durable, attractive, low cost,
standardized and modular, structurally proven, specifically adapted to
the local area, materials and production processes available
Building construction products: light timber frames for low cost
houses, small schools, farms, and light industrial building
Furniture construction products: institutional furniture, household
furniture, furniture for special needs, and playgrounds
Manufacturing: cottage type industries or advanced factories, using
the simplest manufacturing techniques, few tools and limited worker
skills, with quality control build in the process
Joinery: round mortise and tenon timber frame and furniture joints,
low cost through bolt with cross pipe and nut timber frame connectors
Technology transfer: developed and ready to be adopted by
appropriate agencies, user groups, or individuals
Acknowledgments
Rado Gazo
Henry Quesada
Aldo Ramirez Coretti
Rafael Serrano
Robert Leavitt
Yusuf Erdil
Scott Bailey
Gary Moorehead