Experimental investigation of the Structural Perfomance of Engineered Bamboo Composites (Dragonwood) in Jacking Applications

Abstract

Climate change has necessitated gravitation towards bio-based building materials. Many innovative, bio-based, structural products with exceptional strength and resistance, such as mass timber and bamboo composites have emanated from advances in adhesive chemistry and manufacturing to mitigate climate issues.

This study was conducted to investigate the structural performance of an engineered bamboo composite, namely Dragonwood, in jacking applications. While tropical hardwoods have been the common choice for jacking applications across North America; the decline in quality is now raising high level concerns with regards to their performance in jacking applications.

Engineered bamboo composites (EBCs) have been observed to be highly durable, resistant to fungal infection and show high strength to weight ratio. In terms of environmental sustainability, EBCs are a great substitute for tropical hardwoods since it can take as long as 60-80 years for hardwood to mature but bamboo can mature in 2-6 years. Furthermore, with EBCs showing superior long-term behavior under varying environmental exposure, many heavy-duty engineering companies involved in day-to-day jacking applications are incentivized to gravitate EBCs, soon.

The mechanical properties of the Dragonwood specimens were investigated experimentally in bending and compression based on the principal modes of failure to ascertain the performance of these beams in different orientations and loadings. Since the manufacture of Dragonwood involves face bonding two sections of parallel strand bamboo (PSB) boards to form a larger laminated veneer bamboo (LVB) section, glue line failure was also observed.

It was found that in bending, the primary failure mode in the specimens was simple tension as the fibers on the underside of the beams broke due to deflection. Horizontal shear failure was also observed along the glue line in some of the Dragonwood specimens. In compression, the failure mode of the Dragonwood specimens was an overall section buckling characterized by cracks and splits at the end. Regardless, the specimens still demonstrate bilinear behavior both in bending and compression as observed in the stress-strain graphs. With the Ekki specimens, the flexural response was independent of orientation. However, in compression, vertically oriented Ekki specimens were observed to fail in less time than horizontally oriented ones.

From the experimental results, the strength and modulus properties were evaluated, resulting deviations and variances were obtained, and Kolmogorov-Smirnov (K-S) tests were employed to determine the goodness of fit for comparison with known theoretical distributions. From the K-S tests, the experimental data demonstrated conformity with normal distribution.