Guadua-bamboo - World Bamboo Organization

Guadua-bamboo - World Bamboo Organization

17th -22nd Sep. 2015 -Damyang, KOREA
Measurement of the in-plane shear moduli of
Guadua-bamboo
using the Iosipescu shear test method
Dr Hector F. Archila
Researcher - Amphibia Group’s CEO
Iosipescu shear test on Engineered
Guadua-bamboo
structural components
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Motivation behind this work - Material
Why shear?
The actual work
Outcomes
Conclusions
Motivation
Poor man’s timber
Vernacular construction
 Poor design solutions
 Low added value
 Short life span
Poor man’s timber
Scaffolding + Artisan work
 Temporary
 Handcraft
Bamboo scaffolders in Hong Kong by by Jeremy Torr, Jan 6, 2012
Source: Red Bulletin magazine
 Labour intensive
 Not standardized
 High maintenance
A way forward...
Round cane
Structural
Engineered products
•
Traditional construction
Photo: Stora Enso Building Solutions Kroika
tower) Bridport House, London, UK
Industrial System
Straight forward processing by THM
From round Guadua to flat sheets
Heat pressed
Cut into strips
(peeled skins)
Round cane
Flat densified strips
Vertical pressure + Temp.
Engineered bamboo products
for structural applications
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Engineered
Predictable
Durable
Standardisable
Buildable
Viable
Scalable
Testing & Certification
Shear
[Image courtesy of mnartists.org]
Source: https://editions.lib.umn.edu/electionacademy/2012/03/22/paper-cuts-are-the-worst-illin/g
Shear failure
Bamboo & concrete
Shear failure of a bamboo culm along the direction of the fibres
Source: http://www.conbam.info/pagesEN/properties.html
Failure of a reinforced concrete column during the earthquake in Haiti.
Source: http://degenkolb.com/images/uploads/2010/03/Haiti1_2Sinclair/15ColumnShearFailure.jpg
Shear testing
Current methods
Shear failure of a bamboo culm along the direction of the fibres
Source: http://www.conbam.info/pagesEN/properties.html
Shear block method for engineered bamboo.
Source: Correal, J. F., Echeverry, J. S., Ramírez, F., & Yamín, L. E. (2014).
Experimental evaluation of physical and mechanical properties of Glued
Laminated Guadua angustifolia Kunth. Construction and Building Materials,
73, 105–112.
The research
Iosipescu Shear
test
Iosipescu shear test
Novel method
Test diagram
Shear diagram
Ɩ
𝐹
𝑭
𝑭
𝑏/2
𝐹. 𝑏
Ɩ−𝑏
𝐹. Ɩ
Ɩ−𝑏
0
−
𝐹. 𝑏
Ɩ−𝑏
𝑏
𝐹. Ɩ
Ɩ−𝑏
𝑭
𝐹. 𝑏
Ɩ−𝑏
𝑭
+
𝐹. 𝑏
2
−
𝐹. 𝑏
2
Moment diagram
Sample & Iosipescu shear fixture
Wires from strain gauges to
Data Logger (1,2,3,4)
Fixed grip
X2 (T)
X3 (Radial)
Compressive load on X2
X3 (R)
X1 (L)
Ɩ =71.78 ± 0.25
mm
θ = 90º
X1(Longitudinal)
F
Pivot
Adjustable
jaw
Thumb-screw
h = 17.06
± 0.29 mm
X2(Tangential)
Strain gauge
(front face 1-2)
t = 12.07
± 0.12 mm
F’
Face to face strain gauges - Temp= 27º±2ºC, RH = 70±5% - Elastic cycles
Test conditions
From round Guadua to flat sheets
 ASTM D5379 (ASTM 1998);
Pierron & Vautrin (1994)
 Samples conditioned at 27 ±2C
and RH of 70±5% for a period of
20 days (MC=12%)
 Four specimens per sample.
SAMPLES
A
Control ρ = 543.3 kg/m3
B
Dried
814.6 kg/m3
C
Soaked
890.9 kg/m3
Testing & data gathering
F
200kN
cell
Strain gauges +45 & -45 on
front & back faces
Type: Tee Rosette (90º)
Resistance: 350±0.2%OHMS
Gauge factor: 2.12 NOM
load
α = +45
X2 (T)
X1 (L)
2.0
Iosipescu
fixture
Ave. -45
α’ = -45
Ave. +45
1.8
1.6
Specimen
Wires to Datalogger
X2 (T)
Load (N)
1.4
1.2
1.0
-45 front
0.8
+45 front
0.6
-45 back
+45 back
0.4
Ave. +45
0.2
0.0
-15'000
F’
X1 (L)
Ave. -45
-10'000
-5'000
0
5'000
Normal strain (µƐ)
10'000
15'000
Sample C4d
INSTRON 5585H floor model testing machine with a 200kN load cell
Shear modulus (𝑮𝟏𝟐 )
Data analysis
𝑮𝟏𝟐
Shear Cord G (Sample C4d)
18.0
𝒂𝒑𝒑
𝑮𝟐𝟏
𝝉𝒂𝒗
= 𝒂𝒗
ϒ
𝑮𝒄𝒉𝒐𝒓𝒅
𝟏𝟐
∆𝝉
=
∆ϒ
16.0
𝛕
14.0
Shear stress (MPa)
𝛕
=
ϒ
12.0
4,000±200µƐ
10.0
8.0
(ϒ2, τ2)
y = 0.0014x + 0.0982
R² = 0.9999
6.0
(𝑮𝒂 −𝑮𝒃 )
4.0
2.0
(𝑮𝒂 +𝑮𝒃 )
(ϒ1, τ1)
0.0
-2'500
0
2'500
5'000
7'500
10'000 12'500 15'000 17'500 20'000
Shear strain (µƐ) ϒ = |µƐ45| + |µƐ-45|
∙ 𝟏𝟎𝟎
where
∆𝛕 is the difference of shear stress between 𝛕 2
and 𝛕 1 and ∆ϒ is the difference of shear strain
between ϒ 2 and ϒ 1.
𝐺a is the shear modulus of the sample’s side (a)
and 𝐺b is the shear modulus of the sample’s side
(b)
Results
Apparent Shear modulus
Low CoV and St. dev.
𝒂𝒑𝒑
(𝑮𝟏𝟐 )
μ=1.41 ± 0.06
Apparent Shear moduli (GPa)
1.8
1.6
8%
11%
11%
2%
1.4
μ=0.87 ± 0.07
1.2
μ=0.54± 0.05
0.8
0.57
12%
13%
0.49
7%
0.54
0.89
12%
7%
1%
7%
13%
0.79
13%
18%
15%
1.41 1.42
1.40
17%
0.96
28%
15%
0.4
9%
15%
1
0.6
1.41
12%
0.58
0.84
10%
15%
18%
0.2
0
A1
A2
A3
A4
B1
B2
B3
B4
C1
C2
C3
Shear chord modulus (𝑮𝒄𝒉𝒐𝒓𝒅
)
𝟏𝟐
Typical shear stress vs. shear strain graph of specimens A, B & C.
9
Samples C
8
Samples B
Shear stress,
(MPa)
𝛕
7
Samples A
6
5
4
3
2
Chord modulus
(slope)
1
0
-5'000
A1
-1
A2
0
5'000
10'000
15'000
20'000
25'000
Shear strain, ϒ (μƐ)
A4
B1
B2
B3
B4
C1
C2
C3
C4
A3
Shear chord modulus (𝑮𝒄𝒉𝒐𝒓𝒅
)
𝟏𝟐
Box and whisker plots for shear chord results of samples A, B & C.
1.6
GC12
Shear Chord Modulus
(GPa)
1.4
μ=1.32
1.2
1
GB12
0.8
μ=0.69
0.6
GA12
μ=0.41
0.4
0.2
0
543.3
814.6
Density (kg/m3)
890.9
Shear Chord
Modulus
(GPa)
Average, Ga (outer) and Gb (inner) shear chord
moduli values.
0.50
A1, 0.45
A4, 0.40
A3, 0.36
0.30
A1
0.45
0.44
0.46
A (G average)
A (Ga outer)
A (Gb inner)
Shear Chord
Modulus
(GPa)
A2, 0.42
0.40
0.85
0.80
0.75
0.70
0.65
0.60
B1; 0.71
A2
0.42
0.36
0.49
B2; 0.68
B1
0.71
0.83
0.63
B (G average)
B (Ga outer)
B (Gb inner)
A3
0.36
0.34
0.39
B4; 0.69
B3; 0.67
B2
0.68
0.70
0.66
A4
0.40
0.34
0.49
B3
0.67
0.71
0.63
B4
0.69
0.76
0.64
Shear Chord
Modulus
(GPa)
2.20
1.70
1.20
0.70
C (G average)
C (Ga outer)
C (Ga inner)
C3, 1.33
C2, 1.28
C1, 1.26
C1
1.26
1.89
0.94
C2
1.28
1.68
1.04
C4, 1.40
C3
1.33
2.06
0.99
C4
1.40
2.10
1.05
Remarks
A
B
C
𝑮𝟏𝟐
543.3 kg/m3
0.54 GPa
814.6 kg/m3
0.87 GPa
890.9 kg/m3
1.41 GPa
𝑮𝒄𝒉𝒐𝒓𝒅
𝟏𝟐
0.41 GPa
0.69 GPa
1.32 GPa
𝑮𝒓𝒐𝒖𝒏𝒅
𝟏𝟐
0.58 GPa
0.644 GPa
ρ
𝒂𝒑𝒑
Takeuchi-Tam (2004)
Ghavami & Marinho (2005)
Increase in shear modulus » THM modification » Higher density
Twist was high within the 0.1% strain range and stabilized as the
load increased; tangential local crushing was observed.
Conclusions & recommendations
 Adequate method for assessing the shear modulus 𝑮𝟏𝟐 of
small samples of bamboo.
 Setting guidelines for aiding the development of standards
 Errors due to misalignment, twisting and poor specimen
preparation.
 Key for the development of engineered bamboo products
Future of bamboo
Challenge!
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Professionalize the “art”
Exhaustive – rigor
Learn from mistakes
Partnership
International standards
Bamboo based forest sector
Bamboo architecture,
construction and engineering
Acknowledgments
Sponsors
&
Thanks
&
Questions...?
480 to 500
2x MOE & Density (890kg/m3)
kg/m3
Improved Hardness & resistant to decay
Source image: www.ecobuild.co.uk
MOE (GPa)
(Twice more load per unit area)
16
14
12
10
8
6
4
2
0
Ec/t,0
14.86
Ec/t,90
12.48
7.42
CLT-3
6.74
CLT-5
G-XLam 3
G-XLam 5