Non Destructive Test For Grading Of Bamboo Poles For Structural Use

Ramesh Chaturvedia aProfessor (retired) Indian Institute of Technology Mumbai India

cramesh1937@yahoo.co.in

Key words Non-destructive test, Grading, Bamboo poles, Structural use, Test metric (E*I)

Abstract:

This paper presents an attempt, at conception followed by complete design and development of

a set up, that could non destructively, determine a characteristic of a given bamboo pole, that is

a measure of its strength and stiffness properties, and thus provide an assurance of quality for

it’s application in structures. Limitations of the existing IS 6874 and ISO22157 in this regard

are discussed while arriving at a suitable metric (E*I) and the method for it’s determination.

Details of the test setup developed are described along with test results. The concept of treating

Bamboo as a Product rather than a material is another innovation that justifies this method of

testing. A modified design process that is based on the capacity of members to withstand

specified forces, rather than that of the material to sustain stresses has been suggested and

illustrated using the design of a purlin by way of example. The test metric namely (E*I) is

shown to be adequate for design and the test setup is simple, rugged, cheap, effective and fully

functional. However, some extended test runs under field conditions shall be useful to identify

and correct operational problems. The design process need to be extended to other members

such as columns and trusses etc to make it more widely applicable, and to identify other

measures of property of bamboo poles that may be relevant and later to develop the appropriate

test procedures and set ups .

1 Introduction

Bamboo is a Vegetal Rod. Dunkelburg (1) avers that logically Vegetal Rods would have

been the prime components of structures used in the construction of shelters for Human and

Domesticated animals right after the times of the Cave Man. Use of stone and earth may have

been developed concurrently or a little later. However these were the privileges of some of the

mightiest of kings and emperors of that time. Remnants of stone shelters of that time are all that

remain today, while there are few traces of those made of bamboo or earth even though they

sheltered the masses. The advent of bricks, cement concrete, steel, reinforced concrete and sawn

timber (lumber) has all but driven out earth and vegetal rods from structures in urban areas all

over the world, and a fair bit of rural areas except in the poorer countries. Such structures are

vanishing even from there. Few of the Engineering College text books mention them as

materials of construction, the applicable techniques are seldom referred to even in schools

training artisans, and the design methodologies are not part of Engineering Curricula. The

current building codes also do not generally include them as approved materials of construction

and if they do, lay down specifications that are more of a bar rather than an enabler. Little

wonder that even the poor who have used them for generations, now prefer the brick/concrete

for their abodes if they are able to afford the cost.

Though bamboo provides a much greener, cleaner and sustainable alternative to the

modern age materials used in shelters, it requires considerable effort on the part of the research

community well supported by bodies such as INBAR and advocates of a Greener Planet, to

come up with solutions that overcome the negative perceptions. This paper is an attempt to

address the problem of quality assurance.

2 Standards for determination of properties and design of structures.

IS 6874 -1973 (2) was one of the earliest national specification of the method of tests for

Round bamboo. It has been revised in 2008 to bring it in line with ISO 22157-2004 (3). ISO

22156 (4) lays down the specifications for Bamboo Structural Design. These standards, are

similar in structure and content, with the corresponding standards applicable to the more

commonly used materials such as concrete, RCC, and steel. Thus Bamboo Structures that are in

conformity with the above ISOs should be as acceptable as structures in other more commonly

used materials. This should have led to increasing use of bamboo in structures but unfortunately

it has not. Perhaps the reasons can be traced back to the contents of these Standards.

ISO 22156 (4), Bamboo Structural Design, is a rather long document (18 sections, as

many pages) and mostly non specific (just 2 equations). Aiming to match the requirements on

Structural design with more common materials in the details, it virtually shuts out simple

designs by small time individual designers and has restricted growth. Similarly ISO 22157

specifies the method of testing for physical and mechanical properties on the same lines as for

the common materials, and has been providing guidance along the (long and tortuous) path, of

generating and documenting mechanical property data for the numerous (hundreds) species of

bamboo, so that they could be considered for use in structures meeting the standards of ISO

certification, an objective that remains a distant dream.

These standards are expected to lead to generation of a reliable data base of mechanical

properties such as the Elastic Modulus, the values of limit stresses in different stress states such

tension, compression, shear, and bending to form the basis of design. Considerable work has

been done in this direction but the in-effectiveness of the end result can be gauged by observing

table 2 (Safe Working Stresses of Bamboo) in the National Building Code of India, section 3B

Bamboo of Part 6 that deals with Structural Design (5). It specifies (Table2) the safe working

stresses in bending (8.3-20.9 MPa) and compression (10.1-15.4 MPa) as well as the Modulus of

Elasticity(0.64-3.28 GPa) for 16 different species of Bamboo that it approves for structural use.

The specifications in Clause 5 for permissible stresses are rather difficult to interpret. To use

such a guide the designer must be sure of the specie to be used before he ventures on the design.

Designing with conventional materials he has no such problem.

As mentioned earlier courses in design at engineering institutions, and related text books

do not include designing with bamboo. One has to search through special literature such as

Journals, Conference proceedings, special reports, to gain some insight. An attempt by the

Author in this direction revealed that:

• Literature is mostly qualitative

• Designs are mostly done by Architects concentrating on Form rather than structural

performance

• Designs by Bhalla [6] & that on Scaffolding [7], that are analytical, have designs treating

Bamboo Culms as Tubes of constant thickness, and diameter

• Other Texts eg Gutierrez (Inbar TR 19)[8]) & Janssen (Inbar TR 20),[9]) have hardly any

equations for quantitative considerations in design

3 Grading based on Mechanical Properties

The importance of GRADING based on mechanical properties has always been well

recognized. Section 17 of the ISO 22156 [4], Bamboo Structural Design is titled GRADING

and is reproduced below

17.1 Bamboo shall be graded in accordance with approved rules ensuring that

the properties of the bamboo are satisfactory for use, and especially that the strength

and stiffness properties are reliable

17.2 The grading rules shall be based on a visual assessment of bamboo, on

non-destructive measurement of one or more properties, or on a combination of two

methods

17.3 special attention to age, the taper of the culm, the straightness, the

internodal length, and the distribution of nodes

Clause 4.4 of the National Building Code of India Part 6, Section 3b ( 5) deals with

Grading of Structural Bamboo and defines Grading as sorting out bamboo on the basis of

characteristics important for structural utilization as under:

a Diameter and length of culm

b Taper of culm

c Straightness of culm

d internodal length

e Wall thickness

f Density and strength

g Durability and seasoning

One of the above characteristics or sometimes combination of 2 or 3 characteristics form

the basis of grading. The culms shall be segregated species-wise.

It further explains the procedure in subsequent clauses for each of the characteristic. For

diameter it suggests 3 different grades based on its value (each with a fairly wide range) and sub

grades in steps of 10 mm but for length it specifies a minimum preferable value of 6m. For taper

and curvature (straightness), it specifies a maximum permissible value and for wall thickness a

minimum.

Explanations for internodal length, density and strength, and durability and seasoning

are not included, but exclusion of culms with certain visible defects, and other characteristics

e.g. immature, is suggested. Finally it suggests the use of bamboo of at least 4 years of age.

Read with ISO 22156 the above explanation serves the purpose of defining the approved

rules that has been left undefined in Clause 17.1.

While the list of characteristics includes, reliability of strength and stiffness property in

ISO and strength in the Building Code they have been left vague as there are no methods for

Non Destructive Tests for strength/stiffness in existing standards. This gap has been recognized

and there have been a few attempts at development of NDT that could be indicative of strength

and so could form a basis of grading.

Cheng-Jung Lin · Ming-Jer Tsai · Song-Yung Wang [10] has used the measurement of

drilling resistance as a predictor for density, and the measurement of velocity of transmission of

an ultrasonic signal and density, to predict the value of Elastic Modulus. The value of Elastic

Modulus, and the MOR were also determined using a static bend test and the same were

compared with predicted values for a few specimens. There was a positive correlation

(suggesting that these NDT methods could be used). However the coefficient of determination

values were rather low indicating that the predictions may have significant errors. Suneet Tuli

etal [11] have shown that thermal wave imaging can be used to detect sub surface defects in

Bamboo and could be a good NDT test to remove defective pieces during grading

The Gap is recognized by others as well as Trujillo [12], had emphasized on it while

presenting his research proposal “Prospects for a method to infer non-destructively the strength

of bamboo”. INBAR has funded a project at the University of Coventry U.K. The two authors

(Trujillo & Chaturvedi) were however unaware of each other’s work till they were brought

together in Oct/Nov. 2013, by INBAR for submission of a proposal for the GII grant [13].

4 Innovations in Concepts

This author received his first introduction to the area of tests on bamboo only in 2010,

when he was invited by Prof. Sudhakar the Principal Investigator at IIT Delhi of the subproject

“Bamboo as a Green Engineering Material in Rural Housing and Agricultural Structures for

Sustainable Economic Growth “ of the National Agricultural Innovation Project of India [14] .

One of the 5 objectives (No1) was “Study of the rheological properties of Bamboo (Indian

Species) in different agro climatic conditions “[15]. As they had envisaged (based ! on ISO

22157) “close to 10000 tests on just 2 out of 115 species that are common in India” they were

working on developing a machine to test bamboo. Being relatively a novice in this area this

author could think a bit different and so considered the possibility of bypassing ISO 22157 and

came up with a few novel concepts listed below:

Concept 1 Bamboo Poles are a Product (of nature). Since they are not Material ISO

22157, that specifies the method of testing for evaluation material properties may not be used

Concept 2 When we are using Bamboo Poles in Structures, we are using a product.

Since ISO 22156 does not cover this case, it is also not applicable

These concepts lead to the conclusion that it is possible to consider Properties other than

those listed in ISO 22157. For different members of structures we may need to define a different

set of properties of the pole that are relevant to the ability of the pole to perform the function

(ability to withstand forces, moments etc) without failure.

5 New metrics

Author suggested the use of the metric , Product of Elastic Modulus and Moment of

Inertia (E*I) of the individual pole privately to Prof. Sudhakar of Indian Institute of Technology

Delhi and Nripal Adhikari of INBAR . The later supported the concept and was instrumental in

securing a consultation contract for the author to work on the design and development of the

New Concept Test methods and Set ups. The concept was later shared with a wider audience

[16]

There are several advantages in considering this as a good metric namely:

1 The metric relates rather closely to two important parameters in the design of

members of structures viz.:

a Deflection of beams

b Eulers Buckling load for Column

2 The property can be directly and quickly determined through a Non Destructive Test

3 This provides a more reliable estimate of the property for application in design

compared to that obtained through tests for determination of E, and the method of estimating the

value of I as specified in ISO 22157.

Further consideration of the design process of beams led to inclusion of Safe Bending

Moment, and Safe Shear Force in this new list of Metrics. Inclusion of other metrics is

envisaged as the design process is developed. However the emphasis is on inclusion of those

that can be measured using non destructive tests

6 Development of Equipment and Procedure

6.1 Test Equipment: Since the development of test method and equipment was not

constrained by any standards, simplicity, low cost, and suitability for field use were added as

additional parameters besides the usual considerations of adequate accuracy and reliability of

measurements. Bending test was the obvious choice, as E*I could be determined from the

observations of loads and deflection. The test equipment and process specified in ISO 22157

was starting point. It specifies the 4 point test to ensure that the test is under pure bending. Since

this was no longer a consideration the 3 point bending test is a better choice based on simplicity.

A fixed span set up was envisaged for reasons that shall become evident later

6.1.1 4m Test Set Up: ISO 22157 specifies the minimum length of specimen as 30*D

+ atleast half internode length, while IS 6874 specifies minimum at 30*D+ 1m. We expected

the maximum diameter of bamboo to be about 100 mm and so the initial concept was for a

length of about 4m. The set up is shown in Fig1.

Test Setup for 4m NCBT

Figure 1

It consists of two Platform scales of 500 Kg capacity each with a resolution of 0.1 kg.

The supports are fixed on these scales that measure the two reactions. These scales are to be

suitably aligned, positioned and fixed to provide the desired span. The supports were fixed on

car jacks that provided an easy method of height adjustment to suit the different diameters of

bamboo that may come for testing. Application of Load is done by another car jack fixed into a

frame that has to be anchored to the ground. Deflection of the bamboo was measured with

reference to a 600 mm scale fixed in the frame.

6.2 Test Procedure: The load (sum of the two reactions) and corresponding deflections

are read on the scales and recorded, to determine the load deflection relationship. The results

showed this relationship was fairly constant and so the mean value was assumed as the

characteristic and is used to determine the value of E*I for the bamboo pole under test using the

relation

E*I = k* Wi / δi (1)

Where Wi and δi are increments in Load and deflections as measured and the value of K to be

estimated from K= l3/48 on the assumption of a central loading on a simply supported span (a

procedure similar to that in ISO). The value of E*I so determined suffers from significant errors

as the above assumption for k may not be exactly valid, and small errors in measurement of

length leads to much larger variations in result as the relationship has l3.

A trial run indicated that for a bamboo of about 52 mm diameter the loads were only about 44

kg at a deflection of 8 cm. For the load measuring scales that had a maximum capacity of 1000

Kg (2x500kg) these were too low in comparison with the guaranteed accuracy of the devices.

The set up was also rather unwieldy so a change in design was undertaken.

6.1.2 2m set up: The span was reduced to about 2m. This violated the recommendation

in ISO 22157 on length. However it provides the following advantages:

1 Increases the loads to about 8 times the 4m test values. Since the platform scales

were left unchanged the relative errors in load measurements got reduced.

2 The design needed only one platform scale, reducing the cost

3 The span was much more representative of the usual spans of purlins in bamboo

structures used for shelters

Test Setup for NCBT 2m

Figure 2

The set up is shown in Fig.2. The platform scale supports a beam built up of 2 steel

channels that in turn has the supports for the bamboo under test. Jacks are retained to provide

height adjustments for leveling, and to suit the bamboo diameter. V type supports are used to

provide stability and centering ability. The loading is also through Jack fixed below the top

plate in 4 column frame that is fixed to the lower frame of the scale. The movement of the

loading block is measured with the help of a digital vernier scale with a resolution of 0.01mm

and is the measure of deflection. The relatively large section channels, used as support beams

make the assumption of rigid supports reasonably valid.

Another innovation in the test procedure was to introduce an on-site calibration. An

initial test using the setup, with the positions of support blocks and loading block fixed is

conducted using a steel pipe as a reference piece. The value of (E*I)steel for this reference piece

can be estimated fairly accurately from well known values of E for steel (2.0*10^6 Kg/cm2 )

and of I from the dimensions of the tube that are fairly constant and easily measurable. The set

up is used to determine the W/delta for this piece and this result is used to determine the value

of Ks for this setup by

Ks= (E*I)steel * δsteel / W steel (2)

This value Ks is constant for the setup in a specific setting and has no errors due to

measuring errors in length and/or inappropriateness of the load deflection relationship. During

tests the values of W and δ for the piece under test is determined and the value of E*I is

determined from

E*I = (W/ δ)* Ks (3)

This procedure makes the estimate free of errors

arising out of a wrong assumed value of k in the formula E*I = k* W* l3/ δ

due to differences in nature of support

due to wrong measurement of l

due to wrong calibration of load meters (so long as they are linear)

due wrong calibration of the vernier scale

This makes the device and procedure fairly robust and suitable for use in field conditions

where accurate calibration of measurement devices can be a problem

7 Some test Results

Tables 1 to 5 gives the actual readings for loads and deflections observed on the

calibrating steel tube and 4 different pieces of bamboo. It may be pointed out that the device

used for application of load was a car jack and as such the rate of load application was neither

constant nor monitored. For the duration while noting the loads and deflection the jack was in a

fixed position. It was observed that the loads were slightly reducing with time (the resolution of

the scale is 0.5Kg). However the reduction was only about 2kg over about 2 minutes, that is

insignificant, considering the nature of the test. Tests were conducted with a maximum

deflection value between 4- 8 cm as compared to the design limit of approx 0.5cm (L/400).

Observations & Results – 2m NCBT

25-May Specimen Steel 4-Jun Specimen

Bamboo

F 1-Jun Specimen

Bamboo

G

2012 2012 2012

OD Thickness ID OD

OD

42.5 4.5 33.5 1 58.00 1 63.50

I E/104 E*I/104 2 54.00 2 59.10

98276.8 2 196553.6 3 58.00 3 59.10

Average 56.67 mm Average 60.57 mm

Length 5.10 m Length 5.00 m

Weight 5.10 Kg Weight 6.65 Kg

1.000 Kg/m 1.33 Kg/m

Steel Bamboo Bamboo

Load W Vernier Load W Vernier Load W Vernier

Kg mm kg/mm Kg mm kg/mm kg mm kg/mm

72.05 8.15 23.15 7.76 35.95 9.65

146.1 16.07 9.350 44.20 14.77 3.003

74.75 18.83 4.227

218.85 23.65 9.471 64.80 21.48 3.036

109.65 26.76 4.307

282.6 30.32 9.497 84.65 27.62 3.097

140.30 33.67 4.344

340.3 36.35 9.512 103.10 33.33 3.127

169.65 40.23 4.372

391.5 41.93 9.457 120.60 38.84 3.135

195.10 46.21 4.353

136.30 43.85 3.135

217.55 51.78 4.310

152.95 48.48 3.188

240.15 57.16 4.298

Mean 9.457 Ks Mean 3.089

ks Mean 4.319

Ks 20783.06 20783.06 E*I 64194.12

20783.06 E*I 89762.11

Table 1

The bamboo poles used in the tests were approximately 5m long. Data presented in the

tables include raw data (actual readings). The diameter varies significantly. Pie gauge was used

to record the diameters at the two ends and in the centre. The load/deflection values have been

obtained using an averaging approach rather than the best fit line as the method is simpler and

more suitable for field application. In the 5 tests that were made the maximum deviation from

the average was 3% of the mean value in Case 5, which indicates the procedure provides a

fairly reliable value of E*I

Observations & Results – 2m NCBT

1-Jun Specimen

Bamboo

H 4-Jun Specimen Bamboo I 4-Jun Specimen

Bamboo

J

2012 2012 E*I/104 2012 E*I/104

OD OD OD

1 55.00 1 70.00 1 60.00

2 54.00 2 65.00 2 54.00

3 52.60 3 66.00 3 51.30

Average 161.6 Mm Average 67 mm Average 55.1 mm

Length 5.00 M Length 5.00 m Length 5.10 m

Weight 4.90 Kg Weight 7.95 Kg Weight 6.15 Kg

0.980 Kg/m 1.59 Kg/m 1.21 Kg/m

Bamboo Bamboo Bamboo

Load W Vernier Load W Vernier Load W Vernier

Kg mm kg/mm kg mm kg/mm kg mm kg/mm

28.85 9.09 51.05 8.05 35.00 10.59

55.25 17.16 3.271 104.75 16.03 6.729 66.65 19.96 2.978

80.15 24.76 3.274 155.10 23.39 6.783 95.15 28.10 3.209

101.75 31.17 3.302 198.00 29.80 6.756 121.55 35.30 3.337

123.15 37.61 3.306 238.10 35.81 6.738 145.05 41.85 3.388

141.55 43.03 3.321 275.45 41.58 6.693 167.90 48.14 3.428

158.80 48.34 3.311 309.80 46.84 6.671 187.20 53.76 3.429

175.00 53.42 3.297 204.45 59.19 3.401

ks Mean 3.297 ks Mean 6.728 ks Mean 3.295

20783.06 E*I 68530.83 20783.06 E*I 139834.40 20783.06 E*I 68476.32

Table 2

7 New design process

The design process is explained by using the design of a Purlin as an example .The value

of design load in N/m2 on the roof as a combination of dead load, live load and wind load is

determined following the usual process specified in the housing codes. This value does not

depend on any of the parameters of the roof support system (purlin is one part). Typical values

are Dead Load comprising, coverings (150-400) and the estimated weight of purlins (60-150 )

[17] in case of steel structures, Live loads between (400-750) depending on the inclination or

slope of the roof . Method of Estimating the Wind load is rather complex for discussion here but

we may assume its maximum value to be typically 1200 N/m2, acting upward. The codes

permit increasing the allowable stress values by 33% when wind loads are considered. Let us

assume that the design load (Ld) on purlins is 1000 N/m2.In the design of the roof support

system we have to consider the following:

1 The span of the truss (A): Depends on the requirement of the building. However we

may take it typically as 6m and 9m

2 The distance between trusses (B) typically between 0.5 and 2m in steps of .25m

3 The number of nodes (n) on the bottom tie in the truss, n is always odd

The inclination of roof (Θ), the span of the truss (A), and the number of nodes(n)

combine to provide the internodal distance (Cr ) on the top rafter of the truss and the designer

has a free choice on number of nodes.

Cr = A*sec Θ/(n+1) (4)

Assuming that purlins are placed on the nodes of the top rafter only (a good practice that

ensures the rafter is subjected to mainly axial loads) we get the main loading parameter, namely

w the load per unit length on the purlin as

w = Ld* Cr = Ld* A*sec Θ /(n+1) (5)

And the purlin is to be designed as a beam carrying the uniformly distributed load w

calculated above on a span of B. While the purlins as we use are long lengths of bamboo

spanning over several trusses, and hence continuous beams, we treat them as simply supported

in the design for keeping the process simple and it also provides a built in factor of safety

The purlin would therefore be subjected to:

A Max BM M = w*B2/8 (6)

B Max Shear Force F = w*B/2 (7)

C Deflection (ISO800) δ = 5*w*B4/384*E*I = w*B4/(75*E*I) < B/325 (8)

A bamboo pole that is to be used as the purlin should have an assurance that its

E*I > (325/75)*B3*w (9)

Safe Shear Force F > w*B/2 (10)

Safe BM M > w* B2/8 (11)

Let us consider we have a pole which had the test results of Bamboo G for this

application. The test indicated that the value of E*I = 89700*104 kg/m2 . Since there was no

failure upto the maximum load in the test (240 kg), it means that the safe Shear stress is greater

than 120Kg, and safe Bending moment is greater than 120 Kg.m

Since we have a control over the value of Cr in the design process, that controls the

value of w ,we explore the variation of w with the span length B subject to the above

constraints . This is shown in Table 3.

Safe design load w for Bamboo G

SPAN – m

AC.T.V 0.5 0.8 1 1.2 1.5 1.8 2

E*I 897 Kg.m2 1656 404 207 120 61 35 26

M 120 Kg.m 3840 1500 960 667 427 296 240

F 120 Kg 480 300 240 200 160 133 120

Table 3

While the safe value of w is the highest at the lowest span of 0.5 m and the lowest at the

longest span of 2m, according to all the three criteria, the nature of variation is quite different.

Under the given set of properties a span of 1m seems a good choice with the safe value of load

w as 207 Kg/m

9 New Approach to Grading for Structural Applications

The author (16) suggested that the following additional parameters from the NCBT be

also recorded:

o Value of E*I

o Value of weight/length

o Value of safe bending moment M = W*L/4

o Value of Safe Shear Force F = W/2

Culms that have taper and out of straightness within certain narrow limits are suitable

for good quality structural applications. These may further be sorted and grouped as per the

following order:

• Diameter : in steps of 3, 5, or 10 mm. Customer may like to use culms of almost the

same diameter in specific application areas to get good appearance

• Value of E*I, M, and F : Specified values indicates suitability for use in Specific

Situation

• Length : An important characteristic to match the requirement

Culms that are excessively tapered or curved may again be sorted as per scheme above

but with wider steps as they can be used for less critical applications

Grading leads to the following advantages:

o Bamboo Culms sorted in groups with specified dimensional, stiffness, and strength

properties.

o Customer gets what one needs, less wastage and work at site

o Assured stiffness and strength provides assurance of quality, and acceptability of

structure at lowest cost.

o Implemented at plantations, it will enhance incomes in the villages

o It will also enhance demand

10 Conclusions:

1 The test metric E*I gives a measure that is adequate for design of roof purlins

2 The method of test developed gives a fairly good estimate of this value

3 This estimate is significantly better than what can be achieved from results of tests

based on determination of E and I as per ISO 22157 separately and then finding the

product

4 The test set up developed is simple in construction, rugged in construction, and fairly

cheap

5 The metrics and the procedure for its determination are Novel

6 The tests are non destructive.

7 The procedure provides a good first basis for grading bamboo for structural

applications.

11 Further Actions:

1 Extended test runs under field conditions using the developed set up are needed to

identify operational problems and to improve the design

2 Results should be used as a measure, and the metric as one of the parameters of

grading.

3 Application of this process of grading to produce batches of significant numbers

(100 or more) of a single grade from a large lot, and number of batches of differing

properties.

4 Study of the pattern for populations at different sources

5 The existing test setup (2m span) provides a good measure of E*I. However tests

with different spans e.g 1.5m, 1m or 0.75m may be conducted. Results from these

tests can be used to verify the accuracy of the measure

6 The test method also provide further useful information such as values of the safe

bending moment and safe shear force. However these values are underestimates as

no failures were observed. Extensive tests will provide cases of failure, and thus help

us refine the process (e.g. the value of span) that gives better estimates, while it still

remains nondestructive

7 Further work on design of structures based on the approach used in progress

8 Refine the process of testing and design to an extent that it becomes a candidate for

inclusion in ISO

12 Impact on Rural Econonomies

1 The process of grading and design based on the new approach will enhance the

confidence in bamboo structures, and hopefully increase their acceptability.

2 Increased acceptability may lead to greater use in good rural housing, thus improving

the life style at affordable costs for the masses

3 Increased demand should result in more plantation and hence cleaner air

4 Assurance of Better quality will enhance value of the product

5 Cheap and Rugged test set up can be used by the producers to grade their produce

and get better price

6 Increased Housing will provide employment opportunities in the villages

7 Increased use in Villages near the places it is grown, reduces the wasteful use of

energy in transportation to far away markets, and makes a much larger contribution

to local economies.

8 This could be one of the several initiatives needed to improve life in villages

9 Increased use of bamboo in structures reduces the use of concrete, brick and steel

that have a large carbon footprint

13 Acknowledgements

• Dr. P Sudhakar - for invitation (2010) to join in the NAIP and thus introducing me to

this area

• Nripal Adhikari - for continued interaction and providing access to a lot of literature

• INBAR - for engaging me as a Consultant and providing financial and

organizational support in the development

• Students - for discussing their projects,

14 References

[1] Klaus Dunkelberg IL – Team, Bamboo as a Building Material- Straight Rods.

BAMBUS - Bamboo, IL-31, Institut fur leichte Flachentraqwerke (IL), Universitat

Stuttgart, Leitung Frei Otto im Sonderforschungsbereich SFB 64 1985

[2] IS 6874, Method of Tests for Round Bamboo, 1973, Reaffirmed 2002, 2008(First

Revision)

[3] ISO 22156, Bamboo Structural Design:

[4] ISO 22157 (Part I & 2) Bamboo - Determination of physical and Mechanical

properties - 2004

[5] National Building Code of India ,Part 6, Structural Design, Section 3 Timber and

Bamboo , 3B Bamboo

[6] Suresh Bhalla, Scientific Design Of Bamboo Structures ,

www.bambootechnologies.org

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