**6.3. ISO 22157-2 bamboo: determination of physical and mechanical properties: part 2: laboratory manual**

The purpose of this standard, originally written as a technical report is to disseminate best practice test methods in order to make these globally available but also to outline the 'how to' for the tests specified in ISO 22157-1 [15, 16]. On a number of issues, this standard refers to existing national and supranational standards which should be followed, especially for bamboo application in temperate climates (e.g. W. Europe, Canada). This standard contains a number of examples, templates and backgrounds to the tests specified in [15].

be affected by the pull-out force evolution with time due to root growth (**Figure 4**). As shown before, the overall slope stability of a bioengineered slope can be assessed using existing slope stability analysis methods [34] taking into account both long-term (drained) and short-term

The Use of Bamboo for Erosion Control and Slope Stabilization: Soil Bioengineering Works

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Internal stability analysis consists of checking the mechanical capacity of the bamboo culms

The characteristic strength values should be obtained according to ISO 22157 [15, 16]. Suggested characteristic strength values for any bamboo species can be found in [35]. These values should be adapted to the bamboo moisture content by using the moisture content correction factor included in [35] which is based on NSR [36] and EN 384 [37]. Bamboo live pole (pegs) strength characteristic values have been shown in preceding epigraphs (see **Table 3**). The values for the material factor of safety are specified in ISO 22156 [30]. Recommended

In soil bioengineering works, bamboo culms work under Service Class 3 conditions (relative humidity >85%) and in-ground conditions. This situation can be reflected by means of the service class and load duration factor (Kmod) which can be determined from the existing

Other factors making allowance for other conditions (e.g. earthquakes, connection between

Bamboo structures' internal stability checks follow Eurocode 5: Design of timber structures. This design scheme is detailed in ISO 22156 [30] and in [38]. Because of the specific bamboo culm shape, the cross-sectional area to be used in the design calculation is the following:

where *A* is the net area of section; *De* is the bamboo culm outer diameter; *t* is the bamboo culm

By comparing the existing stress values with the element bending capacity, shear, axial ten-

Additionally, Eqs. (2) and (3) can also be useful for determining the minimum bamboo culm

The forces exerted on the bamboo culms can be determined by using traditional structural calculation theory (**Figure 5**). Typically, the moment, shear and axial stress diagrams should

\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Accordingly, the elastic section modulus (*Selastic*) for the bamboo case will be.

sion or axial compression, the internal stability check can be fulfilled.

be generated and their maximum values used for internal stability checks [29].

<sup>4</sup> (*De*<sup>2</sup> <sup>−</sup> (*De* <sup>−</sup> <sup>2</sup>*t*)2) <sup>−</sup> <sup>∑</sup>*area of any holes* (2)

<sup>32</sup>*De* (3)

which are fulfilling structural functions within the ground bioengineering work.

(undrained) conditions.

standards [30, 35].

average thickness.

*A* = \_\_

**7.2. Internal stability check**

values for this factor can also be found in [35].

elements of different rigidity, etc.) can also be found in [35].

Π

*Selastic* <sup>=</sup> Π(*De*<sup>4</sup> <sup>−</sup> (*De* <sup>−</sup> <sup>2</sup>*t*)4)

dimeter fulfilling the internal stability condition [29].

The above ISO standards provide the basis for design with bamboo culms. However, they do not include content relating to living bamboo (design and testing) and the use of a combination of living and inert bamboo in a structure. The existing standards need to be updated and expanded to reflect the growing research on test methods and material characterization of both living and inert bamboo, especially covering the durability and evolution of load transfer mechanisms with time. This update could be partially covered by an attempt to use the existing timber-based test methods for characterization and design [29] which could be beneficial in engaging engineers and architects [31] in the use of bamboo for bioengineering purposes.
