Structural grading of three sympodial bamboo culms (Hitam, Andong, and Tali) subjected to axial compressive load

doi:10.1016/j.engstruct.2018.12.026

Engineering Structures

Volume 181, 15 February 2019, Pages 233-245

https://doi.org/10.1016/j.engstruct.2018.12.026 Get rights and content

Highlight:

•
Structural grading of bamboo culm could be conducted by using strength or capacity grading.
•
Density is good predictor for estimating the compressive strength, while linear mass is the best one for estimating the load carrying capacity.
•
Capacity approached is better than strength approach in bamboo construction design.

Abstract

Bamboo culm is commonly utilized in columns that are subjected to axial compressive load, thus it is necessary to measure its compressive strength and load-carrying capacity. The variability of culm dimension, geometry, moisture content, density, and linear mass of three sympodial bamboo species belonging to the Gigantochloa genus [Hitam (Gigantochloa atroviolacea), Tali (G. apus), and Andong (G. pseudoarundinacea)] were studied to determine the best predictor for structural grading of these culms based on their compression properties. Two types of structural gradings, strength and capacity gradings, were examined. Strength grading was developed assuming a hollow or solid circular section of the bamboo culm. Both strength and capacity gradings sufficiently classified culms of all three species into several structural quality classes based on a strong correlation (r) between the predictor and dependent variable (r = 0.83–0.97); however, capacity grading proved to be the best type of structural grading because the maximum compressive load carrying capacity (F_c) of bamboo culm could be predicted more precisely and accurately compared with the compressive strength (σ_c). Additionally, it was found that linear mass was the best predictor for estimating the compressive capacity (F_c) (r = 0.89–0.98), culm density for estimating compressive strength assuming a solid circular section (σ_cc) (r = 0.84–0.92), and wall density for estimating compressive strength assuming a hollow circular section (σ_cw) (r = 0.73–0.89). Based on these predictors, capacity and strength gradings for bamboo culms subjected to compressive load were developed, permitting categorization of bamboo culms into structural quality classes. Each structural quality class had a 5% lower value and characteristic value for σ_c and the maximum compressive load, which became design values for bamboo structural design.

Introduction

Bamboo is an eco-friendly and renewable material and is traditionally used for construction of housing in Asia, the Pacific Islands, the United States of America, and Africa. Bamboos grow rapidly, at a maximum rate of approximately 21–30 cm/day when they are young [4]. Bamboo forests create a microclimate that improves the comfort of the surrounding community because of its contribution in maintaining the temperature and relative humidity thus the heat index is in comfort zone for longer period daily [6]. Bamboo cultivation should therefore be encouraged to improve environmental conditions and to support the sustainability of green building materials. Traditional bamboo houses are commonly constructed using culms and bahareque as primary building materials, whereas modern bamboo houses may be built using culms, laminated boards, veneer, and panels. Bamboo buildings are light and strong and can reliably withstand earthquakes. In addition to housing, bamboo is used in the building industry (for constructing bridges, frames, and scaffolding) and for flooring, cabinet-making, furniture, and fencing. It is also suitable for decoration such as in fountains, grates, and gutters.

Construction design may follow a stress-based or capacity-based approach. The stress-based approach involves material properties such as modulus of elasticity (E), modulus of rupture (σ_b), tensile strength (σ_t), and compressive strength (σ_c), whereas the capacity-based approach involves parameters such as flexural rigidity (EI), maximum bending moment (M_max), axial stiffness (EA), and maximum axial load (P_max). Trujillo et al. [26] suggested that the capacity-based approach is more suitable for bamboo construction designs than the stress-based approach because bamboo structural grading could predict EI and M_max better than E and flexural strength of bamboo culms. Chaturvedi [7] and Jangra [14] also suggested applying EI and M_max for bamboo structural grading. Nurmadina et al. [22] conducted similar research on bamboo structural grading of Gigantochloa apus and reported that a combination of linear mass (q) and square of diameter (qD²) and qD were the best predictors for EI and M_max, respectively. Findings of several studies [26], [7], [14], [22] analyzing bamboo flexural properties justified that capacity grading was better than strength grading. In the present study, both capacity and strength gradings were developed based on bamboo culm compressive properties. The mechanical properties, including axial compressive strength of bamboo culm are frequently studied, but the structural grading of bamboo culm subject to axial compression load is still missed.

This research analyzed the variability of culm dimensions and geometric and physical properties of three sympodial bamboo species of the genus Gigantochloa [Hitam (G. atroviolacea), Tali (G. apus), and Andong (G. pseudoarundinacea)]. Subsequently, the parameters that were the most suitable for predicting compressive properties of bamboo culm were determined. Both strength and capacity gradings were developed and compared to obtain the best method for bamboo structural grading based on compressive properties. The structural quality class interval, 5% lower value (R_0.05), and characteristic value (R_k) of each class were developed using the confidence band [22] and ISO 22156 methods [12]. R_k was the design value of a bamboo member.

Section snippets

Sample condition

A number of 50, 51, and 54 stems of bamboo hitam, tali, and andong culms were cut from villagers’ plantation in Sukabumi, West Java, Indonesia. This research used only 7 m long of the bottom of bamboo culm. Two pieces of sample were cut from every 7 m culm, one pieces from the top and one pieces from the bottom. Short lengths of 100, 102, and 108 pieces of Hitam, Tali, and Andong bamboo culms, respectively, were compression tested. The sample length (L) was approximately equal to the diameter (D

Dimensions

D and t varied by the species and environmental conditions. For Hitam bamboo culms, mean D was 67.27 (range, 46.92–94.4) mm (Table 1), which was similar to that of Tali (mean, 63.93 mm; range, 39.59–96.0 mm) (Table 2). For Andong bamboo culms, D was larger, with a mean of 91.57 (range 57.68–114.7) mm (Table 3). Based on D, bamboo culm of the three species was found to be suitable as a structural material. Kaminski et al. [17] suggested that bamboo culm for structural use should have a D of

Conclusions

Structural grading of Hitam, Andong, and Tali bamboo culms subjected to compressive load could be conducted using either strength or capacity grading because they have strong correlation with the indication predictor; however, capacity grading is preferred because compressive load-carrying capacity has strongest correlation value with linear mass (q) among others. q was the best predictor for maximum compressive load (F_c) estimation, ρ_c was the best for estimating compressive strength assuming

Acknowledgment

Authors would like to acknowledge Ministry of Research and Higher Education–The Republic of Indonesia, and Bogor Agricultural University for providing an opportunity to conduct this research.

References (33)

F. Albermani et al.
Lightweight bamboo double layer grid system
Eng Struct
(2007)
K.F. Chung et al.
Mechanical properties of structural bamboo for bamboo scaffoldings
Eng Struct
(2002)
T.Y. Lo et al.
Strength analysis of bamboo by microscopic investigation of bamboo fibre
Const Build Mater
(2008)
Nurmadina et al.
Structural grading of Gigantochloa apus bamboo based on its flexural properties
Const Build Mater
(2017)
C.S. Verma et al.
Comparative study of mechanical properties of bamboo laminae and their laminates with woods and wood based composites
Compos B Eng
(2014)
Q. Xu et al.
Mechanical properties of structural bamboo following immersion in water
Eng Struct
(2014)
W.K. Yu et al.
Axial buckling of bamboo columns in bamboo scaffolds
Eng Struct
(2005)
W.K. Yu et al.
Column buckling of structural bamboo
Eng Struct
(2003)
M. Ahmad et al.
Analysis of calcuta bamboo for structural composite materials: physical and mechanical properties
Wood Sci Technol
(2005)
J. Baets et al.
Compressive properties of natural fibre composite
Mater Lett
(2015)

E.T. Bahtiar

Keandalan Bambu untuk Material Konstruksi Hijau [Dissertation]

(2015)

E.T. Bahtiar et al.

Eccentricity effects on Bamboo’s flexural properties

J Biol Sci

(2013)

E.T. Bahtiar et al.

Human comfort period outside and inside bamboo stands

J Environ Sci Technol

(2014)

Chaturvedi R. Nondestructive test for grading of bamboo poles for structural use. 16th Nocmat, Winnipeg. 2015 Aug...

A. Firmanti et al.

Mechanical stress grading of tropical timbers without regard to species

J Wood Sci

(2005)

R. Gnanaharan et al.

Bending strength of Guadua bamboo: comparison of different testing procedures

(1995)

Cited by (42)

Characteristic and allowable compressive strengths of Dendrocalamus Sericeus bamboo culms with/without node using artificial neural networks
2024, Case Studies in Construction Materials
The strength of construction material is a crucial consideration in the process of structural design and construction. Conventional materials such as concrete or steel have been widely utilized due to their predictable material performance. However, a significant obstacle to the widespread use of bamboo in structural elements lies in the challenge of its standardization. Many previous research studies have explored bamboo’s load bearing capacity, but the information remains limited due to variations in species, size, age, physical properties, moisture content, and other factors, making it difficult to predict their load-bearing capacity. This study aims to propose Artificial Neural Network (ANN) models to predict ultimate compressive load and compressive strength of Dendrocalamus Sericeus bamboo culm. Additionally, for structural design purposes, the proposed ANN models were employed to determine the characteristic and allowable compressive strengths. As a first step, experimental data from compressive tests in the literature were used for training and developing the ANN model. To investigate the effect of the node on compressive loading capacities, the test data were separated into two datasets, “Node” samples and “Internode” samples. Through the training process, ANN models were finally proposed, and the R-square values for the prediction of ultimate compressive load and compressive strength from the proposed ANN models were significantly higher than those obtained from the linear regression analyses used in the literature. Subsequently, the characteristic and allowable compressive strengths were calculated and compared to the strengths obtained from the experiment data, revealing a difference of approximately only 8.0%. Overall, the ANN models presented in this study offer promising predictive ability for both ultimate compressive load and compressive strength of Dendrocalamus Sericeus bamboo culm, as well as for determining characteristic and allowable strengths. Hence, ANN models are suggested to be adopted as a tool for the design and construction of bamboo buildings.
Grading bamboo through four-point bending tests. A report on six species of Italian bamboo
2023, Construction and Building Materials
The adoption of natural construction materials can help mitigate the environmental impact of the construction industry by reducing the amount of energy required and emissions. Among the natural materials, bamboo is a remarkable option, combining high mechanical resistance with a low specific weight and a very high growth speed; however, its application is limited by the absence of a suitable grading method. This paper aims at filling this lack by providing a strength-based grading methodology relying on a four-point bending test. Experimental results were processed considering bamboo both as a homogeneous material and as a non-homogeneous material and using the ANOVA test. Results show that statistical groups can be defined which are not based on the bamboo species, but on the values of the mechanical properties, hence supporting the appropriateness of strength classes. The bending tests used in this paper could be a crucial test for bamboo grading: it is easier to perform than a tensile test and it gives complete information on the change of material properties along the culm wall thickness. The study focuses on six different species of bamboo grown in Italy, for which little data is present in the literature.
Structural bamboo composites: A review of processing, factors affecting properties and recent advances
2023, Advances in Bamboo Science
Bamboo is a widely available bio-resource that is considered as a sustainable and eco-friendly raw material for fabricating composites that could replace timber and timber-based products. Several structural bamboo composites (SBCs) have been developed as a sustainable alternative to traditional load-bearing materials in different applications. These composites utilise bamboo in its converted forms viz., strips or strands, bonded with structural grade polymeric adhesives, and compacted and cured under pressure and at high temperature, forming thick panels or beams with standardized cross-sections. With recent advances in processing technologies, several interventions have been undertaken to improve the production efficiency and overall properties and performance of SBCs. While the properties of these composites are comparable or even better than those of commonly used wood and wood-based mass timber products, their performance is strongly influenced by the different processing parameters used in their fabrication. This article presents a comprehensive overview of the recent literature about the production process of SBCs and their physico-mechanical and other properties, factors affecting these quality parameters and current developments in processing technologies. It also examines potential applications and the future scope of research work in this area.
Multi-culm bamboo composites as sustainable materials for green constructions: section properties and column behavior
2023, Results in Engineering
Round bamboo culms offer excellent sustainable materials for a green building construction. Round bamboo culms are tied or fastened into a multi-culm composite member to resist the heavier load. Circles externally touching each other can well model a multi-culm bamboo composite's section. This study aimed to obtain formulas for drawing a cross-section of a multi-culm bamboo composite, calculating its section properties, and then embedding them into a graphing calculator and spreadsheet. As many as nine full-sized single and multi-culm bamboo composite columns were tested in the laboratory to resist the buckling load until the failure occurred. The column acting as the sum of some individual culms capacity was considered. In addition, the embedded equations analyzed the multi-culm column working in unity as a composite. This study found that the multi-culm columns tend to inhibit the combination (pseudo-composite) behavior rather than acting as a perfect composite column or the sum of individual culm's capacities. A perfect composite columns approach resulted overestimated value of the multi-culm column's critical buckling load; on the other hand, the sum of individual culm's capacity approach approximated underestimated value. The weighted average approach with a weight coefficient of k = 1 explains the empirical critical buckling load-bearing capacity's variance very well.
Inference of mechanical properties and structural grades of bamboo by machine learning methods
2022, Construction and Building Materials
Citation Excerpt :
The first objective of this study was to pool datasets to have a more robust, and hence conclusive, process for the determination of characteristic values. A secondary objective was to complement and continue the work undertaken by others [12–15] regarding the determination of the most appropriate geometrical and/or physical properties that provide reliable correlations to infer mechanical properties. The analysis procedures are linked to the new ISO standards.
Features such as fast–growth rate, high strength–to–weight ratio, high carbon sequestering capability amongst others, make bamboo an excellent alternative environmental–friendly construction material. Therefore, it is very important to establish the most appropriate geometrical and/or physical properties that can be used to infer capacities as well as structural grades for bamboo such as Guadua angustifolia Kunth (GAK). Thus, an extensive experimental characterization of physical and mechanical properties of GAK was conducted by two independent laboratories –with samples from the same plantation in Colombia. Pooling of the two datasets were performed in order to create a larger data and undertake a more rigorous statistical analysis using machine learning (ML) methods. In addition, regression equations of mean and characteristic values for parallel–to–fiber compression, shear and bending capacities, and flexural stiffness were determined based on ML methods employing geometrical and physical properties. Finally, ML methods were used to propose a classification method based on four capacity classes that could enable a simpler grading process for structural bamboo species such as GAK.
Environmental and mechanical performance assessment of bamboo culms and strips for structural use: Evaluation of Phyllostachys pubescens and Dendrocalamus giganteus species
2022, Construction and Building Materials
The environmental and mechanical performance of bamboo culms and strips for their use in construction are evaluated considering two species: Moso (Phyllostachys pubescens) and Dendrocalamus giganteus. Life Cycle Assessment (LCA) was used for the environmental performance assessment. For the mechanical performance evaluation, the following tests were performed: compression of culms parallel to fibers, bending, and longitudinal tensile tests. Moso species performed better both environmentally and mechanically. This study brings important ecodesign information about two species of bamboo for different applications that can facilitate its use in the construction industry, thus contributing to a bioeconomy and a low carbon pathway.

View all citing articles on Scopus

View full text

Structural grading of three sympodial bamboo culms (Hitam, Andong, and Tali) subjected to axial compressive load

Highlight:

Abstract

Introduction

Section snippets

Sample condition

Dimensions

Conclusions

Acknowledgment

Eng Struct

Eng Struct

Const Build Mater

Const Build Mater

Compos B Eng

Eng Struct

Eng Struct

Eng Struct

Analysis of calcuta bamboo for structural composite materials: physical and mechanical properties

Wood Sci Technol

Compressive properties of natural fibre composite

Mater Lett

Keandalan Bambu untuk Material Konstruksi Hijau [Dissertation]

Eccentricity effects on Bamboo’s flexural properties

J Biol Sci

Human comfort period outside and inside bamboo stands

J Environ Sci Technol

Mechanical stress grading of tropical timbers without regard to species

J Wood Sci

Bending strength of Guadua bamboo: comparison of different testing procedures