Doctor of Philosophy (Ph.D.)
Degree Granting Department
Civil and Environmental Engineering
James R. Mihelcic, Ph.D.
Gray Mullins, Ph.D.
Michael MacCarthy, Ph.D.
Delcie Durham, Ph.D.
Alan Franck, Ph.D.
Strength Properties, Infrastructure, Wood, Sustainable Development Goals, WASH
With exponential global population growth occurring and associated environmentally destructive consumption of natural resources, alternative materials that are fast growing and sustainable are being sought out to satisfy human needs. One material that is fast growing and sustainable that can be used to meet most basic needs of humans (i.e. shelter, food, tools) is the plant bamboo, of the grass family Poaceae. Bamboo was used in the past by native peoples who lived in the environment where bamboo natively grows (all continents except Europe and Antarctica) with proven success for uses such as shelter, piping, tools, wells, food, fencing, baskets and much more. These practices were mostly abandoned and deemed obsolete due to the introduction of long lasting ‘modern’ building materials of steel and concrete which gained popularity in the 1800s. Now, in the current century with much advancement in science, technology, and education, humanity is reconsidering many practices and returning to more ancient practices and ways that are better for human health, the environment, and overall sustainability.
These environmental considerations are drivers of this research, which focuses on how to use bamboo for engineering applications. First, in order to use a material for engineering and design applications, a material must be destructively tested to attain material property values. Therefore, a critical examination of the bamboo mechanical property values published literature was performed. It was found that although many scientists all over the world have been working on mechanical property testing of bamboo, their results have been published in different journals, in different languages, and had not yet been aggregated and compared. This led to the first study in this work that analyzed mechanical property data from 43 bamboo peer-reviewed publications written in English, Spanish, and Portuguese (the three main languages in which bamboo literature is published). This study focused on aggregating mechanical property values, establishing a range of values for each property as well as an average, and correlating the difference in property values to bamboo variables stated in bamboo literature (age, bamboo species, density, moisture content, post-harvest treatment, and testing standard employed). The five mechanical properties reviewed were: shear strength, compressive strength, tensile strength, bending strength / modulus of rupture (MOR), and modulus of elasticity (MOE) and their average values were 9 MPa, 52 MPa, 159 MPa, 120 MPa, and 16 GPa, respectively. Although a thorough graphical set of analyses were performed attempting to correlate the difference in mechanical property values to the previously listed variables, and only main variables found to influence strength values were moisture content and specific testing standard employed.
The results of the high range of mechanical property values with no variable with which to separate the results to lower the range, led to the second part of the research. It incorporated the high range of values reported in the literature but was able to establish safety factors and reduction factors alongside corresponding failure rates. This work allows for a designer to use bamboo culms choosing a failure rate he/she deems appropriate for structural bamboo construction. The analyses in this work were performed using Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD) equations applied to bamboo as well as Monte Carlo statistical analyses for verification. The raw data and statistically analyzed data of 25 publications were used for this analysis, yielding 3806 strength test values (shear strength, compressive strength, bending strength / modulus of rupture, and tensile strength). Shear strength safety factors ranged from 1.38-3.58 for failure ratios from 1:6-1:25000; compressive strength from 1.30-2.79; bending strength from 1.43-4.03; tensile strength from 1.66-7.43. No singular safety factor is suggested for design as that is due to the judgment of the designer of what failure ratio he/she deems appropriate for the specific application.
Although many compression tests have been performed on bamboo, there are no known tests which destructively test bamboo after an extended period of time after harvesting (more than ~3 months). This experiment conducted a field experiment to test the functionality of using bamboo for the application of installing bamboo wells to provide groundwater. The bamboo tested in the third part of the study was of two species, Dendrocalamus giganteus and Dendrocalamus asper half of which were 1) air-dried in a laboratory for 3.5 years and the other half of which was 2) inserted in the ground as bamboo wells. The bamboo culms (or poles) had been separately treated in three different ways right after cutting: 1/3 with a borax and boric acid solution (most conventional treatment in the industry), 1/3 with coconut oil (experimental treatment in the literature), and 1/3 air-dried, a non-treated control. Bamboo wells are said to be used in ancient times as well as in more recent applications in the 1990s in India by small scale farmers. The publication of bamboo well studies have been very few and nearly no scientific analyses had been performed on them. Therefore, six bamboo wells were assembled and installed at the University of South Florida Geopark, the first of their kind in the U.S. These wells were half of species D. giganteus and half of species D. asper and also treated individually using the three different treatments described above. The wells were monitored for pH and presence of leached boron for a 3.5-year monitoring period and then removed. Upon removal, the bamboo well casings were examined for molds present as well as by mechanical compression testing to assess degradation in comparison to each other (of different treatments) and to air-dried control samples maintained in the laboratory for 3.5 years. The mold fc. Acrodictys was observed to cover the entire inner portion of the bamboo (inner diameter), from the surface level up to the water table. The lab air-dried control samples had compression strength and compressive modulus of elasticity values correlating to those found in the literature, 44-90 MPa (72 MPa average) and 15-31 GPa, respectively. Removed well samples exhibited compressive strengths and compressive modulus of elasticity values of 22-61 MPa (39 MPa average) and 7-25 GPa, respectively. This study revealed that bamboo wells were feasible and although their compressive strengths lowered by around a half after being in the ground for 3.5 years, their compressive strength and compressive modulus of elasticity values were still in the range of bamboo tested in the literature.
Scholar Commons Citation
Sánchez Vivas, Lorena, "Bamboo as a Sustainable Engineering Material: Mechanical Properties, Safety Factors, and Experimental Testing" (2019). USF Tampa Graduate Theses and Dissertations.