The effect of constituent units on the vibration reduction of bamboo engineering materials: The synergistic vibration reduction mechanism of bamboo stiffness and wood damping

Abstract

Determination of the influence and mechanism of constituent units on the vibration reduction performance of bamboo engineering materials is required to optimize application of these materials in the fields of construction and transportation. Testing was performed of typical bamboo engineering materials of Bamboo scrimber (BS), bamboo-wood composites (BWC), and Bamboo Glued laminated timber (GLT), all with different constituent units. Vibration reduction performance and parameters of vibration models were determined and compared using point-by-point multi-point tests and modal parameter identification methods. On this basis, equivalent stiffness was approximated based on inherent frequency. The results show that, BWC had the best vibration reduction performance, followed by BS, and GLT. The first three-order damping ratios of BWC were the largest, 2.14 %, 2.52 %, and 2.43 %, and those of GLT were the smallest, 1.40 %, 1.58 % and 1.60 %. Overall, the equivalent stiffness of the tested materials was in the order of: BS>BWC>GLT. The first three-order modal shape resembled the typical first-order quadrilateral torsional bump, the second-order middle-position bending bump, and the third-order bending-torsional bump. The resonance bands were mostly distributed at the middle position for GLT and BS, and at both ends of BWC. Vibration reduction of GLT was mainly attributed to the vibration reduction of solid bamboo, that of BS was mainly due to the high stiffness vibration reduction of bamboo fibers after recombination, and that of BWC resulted from the synergistic effect of the rigid surface layers and the even lamination of the low density and high porosity damping core layer after bamboo veneers. These results provide scientific reference for the vibration reduction design and optimization of bamboo engineering materials for applications in the fields of construction and transportation.