The Off-Axis Embedment Performance of Bamboo Panels Used for Glubam Structures

The off-axis embedment behaviors of unidirectional and multidirectional laminated engineered bamboo panels used for glued-laminated bamboo (glubam) structures under dowel-type bolts with three different diameters, 12, 14, and 16 mm, were experimentally studied in this research. The half-hole loading method given by current standards was adopted to perform the embedment tests. Seven different off-axis loading directions from 0 degrees to 90 degrees related to the main bamboo fiber direction at an interval of 15 degrees in the panel plane were considered. The different failure patterns, stress-displacement curves, and the corresponding full-field surface strain measured through the digital image correlation (DIC) method are reported. The loading angles significantly influenced the embedment performance of unidirectional bamboo panel specimens, and the strength values decreased with the increasing off-axis loading angles. A difference of 35% in the strength values between 0 degrees and 90 degrees loading specimens was observed. However, quasi-isotropic embedment properties were noticed for the multidirectional laminated engineered bamboo panels. The capacity functions were provided to predict the mean off-axis embedment strength and characteristic strength values by inputting the characteristic density values into the functions. Compared with the characteristic strength values estimated through the statistical method, with a 95% probability of exceedance and 75% significant level, the conventional capacity-function method underestimated the off-axis embedment strength values, and thus may leading to an overconservative design. The statistical characteristic embedment strength values are suggested to be used to calibrate the safety factor of capacity equations given by wood standards. Results from this research can be used to predict the ultimate strength of glubam joints under complex loading conditions and obtain reliable design values for engineering applications.

Automated summary

The off-axis embedment behavior of unidirectional and multidirectional laminated engineered bamboo panels used for glued-laminated bamboo structures was studied in this research. Different failure patterns, stress-displacement curves, and surface strain were reported. Loading angles significantly influenced the embedment performance of unidirectional panels, while quasi-isotropic properties were noticed for multidirectional panels. The capacity functions were provided to predict the mean off-axis embedment strength and characteristic strength values.