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Bamboo Structural Material

Compared with wood, bamboo has many advantages like greater strength, tenacity, rigidity, better physical-mechanical performance. Consequently, Hardwood flooring is now being replaced by floor board in cold countries.

Short discrete vegetable fibers i.e. bamboo has been examined for their suitability for incorporation in cement concrete. The physical properties of these fibers have shown no deterioration in a concrete medium. It is shown that workable and homogeneous mixes can be obtained using a special method of proportioning. While compressive and tensile strengths of vegetable fiber concretes are no higher than those of control concrete, their deformation behavior shows improvement in ductility and reduced shrinkage. Impact and fracture toughness of vegetable fiber concretes are also distinctly higher.

Bamboo has strong molecular structure yet it requires post-harvest processing before using it in bicycle frame. After cutting, bamboo needs heat-treatment in which bamboo tubing is treated with hand-held blow torch. The heating maximizes the strength of the bamboo through changing the properties of the fiber. At present, there is no distinctive evidence of how the fiber transforms yet it is theorized as the process similar to boiling sugar syrup. After drying, the internal juice become stiff which brings strength to the bamboo of which if a bicycle is made, it can be ride but still it would be supple.

World ANALYSIS values
Compressive Strength kN/cm²	d=60mm	d=32mm
Parallel towards fiber	6,36	8,63
Vertical towards fiber	5,25	9,3
Mechanical properties of bamboo
	d=80mm	d=30mm
Tensile Strength kN/cm²
Outer fibers
	min=30,68	min=35,74
	max=32,73	max=38,43
Inner fibers much lignin
	min=13,53	min=14,84
	max=16,33	max=19,47
Complete wall thickness
	min= 16,27	min=23,25
	max=21,51	max=27,58
Elastic modulus Compression kN/cm²
	dia mm	d=100	d=80	d=70
	minimum	1519	1890	1650
Elastic Modulus tension kN/cm²
	dia mm	d=90	d=80	d=70
	min.	1700	1790	1840
	max.	2200	2410	?
Elastic modulus bending kN/cm²
	dia. mm	d=100	d=70	d=30
Outer fibers		1690	2270	3250
Inner fibers		1360	1890	-
Complete bamboo average		1700	2200	2450
Modulus for Flexural bending kN/cm²
	dia. mm	d=100	d=80	d=70
	Min.	1,519	1,890	1,650
Shearing strength kN/cm²
	Whole stem	min=1,69	max=2,31	average=1,98
	Only tube	min=1,47	max=2,22	average=1,67

Compressive strength fc,0	5, 6 kN/cm²
Compressive strength Ec,0	1840 kN/cm²
Average bending strength fm	7,4 kN/cm²
Average bending strength at perfect drying	10 kN/cm²
Average elastic modulus of bending	1790 kN/cm²
Average elastically modulus of tension	1900 kN/cm²

all KN/cm²
	tensile strength	compressive strength	elastically modulus	bending strength
DB-magazine	14,8-38,4	6,2-9,3	2000	7,6-27,6
Dr.S.Eicher	-	5,6	1840	7,4-10
Dr.H.Lopez	19,19	3,93	2150	-
Prof.Janssen	-	-	1760	14,48

Statistically Averaged Bambusa Balcooa 4+ years mature Upper Assam

All kN/cm²

Elastic modular 1800
Tensile strength 15,0
Compressive strength 3,9
Bending strength 7,6
Thrust 0,9
d=12cm; d=9cm averaged
A=50cm² cross section
W=100cm³
I = 700 cm⁴

LBSL Bamboo Strength
The parameters that affect the strength and stiffness of Laminated Bamboo Strip Lumber LBSL are :

Presence of voids
Glue imperfections
Orientation of bamboo material

Finite element FE models could be developed to study the effects of the parameters on the strength and stiffness of LBSL beams and bamboo reinforced timber beam, i.e.,

FE model of bamboo strip
FE model of LBSL with different arrangement/orientation of bamboo material
FE model of voids in the composite system
FE model of non-glued surfaces in the composite system
FE model of shear failure (in a case of shorter and deep LBSL beam)

Furthermore, non-linear finite element analysis would also be included to study the plastic bending behavior of bamboo strip and LBSL beam.

Mechanical Properties of Bamboo Strip

Knowledge on mechanical properties of bamboo in strip forms (strip or strand) is very important because LBSL contains bamboo in these forms. Studies on the anatomy of bamboo internode cross-section have revealed that the strength properties change (increase) from inner to outer layer of the culm.

Figure 1 : Anatomical Features of Bamboo Internode

These microstructure features cause bamboo split to behave differently under different bending modes, i.e.,

with load on top of outer layer
on top of inner layer and
on side.

Figure 2 : Different Type of Loading for Bending Test

Thus, it is envisaged that orientation of bamboo strips in LBSL would affect the strength behavior of the bamboo composite. Numerical modeling on the strip would be used as a tool to study the effects.

Modeling of Bamboo Strip

There are several approaches to model bamboo strips.

Morphological-Based
In this approach, the parameters of the model are based on physical properties of the material's microstructure. In the case of bamboo strip, it could be modeled as orthotropic unidirectional fibrous material. This model would be useful in the analyses such as to determine strength, fracture toughness and fatigue life that require local stress-strain characteristic inputs.

Figure 3 : Bamboo Strip as Orthotropic Unidirectional Fibrous Composite
(Notes * = Amada et al 1996)
Laminated Composites
The bamboo strip could also be modeled as a laminated composite with several unidirectional continuum layers each with unique mechanical properties.

Figure 4 : Bamboo Strip as Multiple Continuum Layers

This model would be appropriate to study the bending behavior of bamboo strip subjected to different loading types and to explain the dissimilarity between the load-displacement curve characteristics.
2-Layer Composite
This is the simplified version of laminated model mentioned above. The bamboo strip is composed of two layers of distinctive mechanical properties where the outer layer is much stronger than the inner layer.

Figure 5 : Bamboo Strip as 2-Layer Composite

This could be the most economical model for future numerical analysis of Laminated Bamboo Strip Lumber (LBSL) Numerical Works

The aim of current numerical analysis is to produce load-displacement curves for bamboo strip subjected to simple bending load. The work started with the 2-layer composite model below.

Figure 6 : Load and support arrangement
(Dimensions in mm)

The parameters that affect the strength and stiffness of Laminated Bamboo Strip Lumber LBSL are :

presence of voids
glue imperfections
orientation of bamboo material

Finite element models could be developed to study the effects of the parameters on the strength and stiffness of LBSL beams and bamboo reinforced timber beam, i.e.,

FE model of bamboo strip
FE model of LBSL with different arrangement/orientation of bamboo material
FE model of voids in the composite system
FE model of non-glued surfaces in the composite system

and, in a case of shorter and deep LBSL beam,

FE model of shear failure

Furthermore, non-linear finite element analysis would also be included to study the plastic bending behavior of bamboo strip and LBSL beam.

Final Choice of Bamboo Breed /Location/Age :

Apart from average test Properties, Luit Nirman uses peoples’ hereditary Experience and folk wisdom to make the best /optimum/minimum-waste. We offer choice of Bamboos for all applications.

World’s users can rest assured of quality and selection and prompt service from LUIT NIRMAN

Strength in Concrete : Bamboo is a high strength material that can be used, in certain cases, as reinforcement in concrete. As concrete matrix has a high pH, many authors have discussed the decay of vegetal materials when used to reinforce cementations matrix. This paper presents results of an experimental investigation made to evaluate bamboo durability to be used as concrete reinforcement. The durability was evaluated by changing the tensile strength and Young’s Modulus of bamboo.