The influence of bamboo scrimber cotters on sound insulation and mechanical properties of cross-laminated timber
Sound insulation is to minimize the sound transmission from one room to another,which is an important property for building materials.In order to improve the low and medium frequency sound insulation performance of cross-laminated timber(CLT),a two-dimensional phononic crystal structured CLT with bamboo scrimber square cot-ters as the acoustic scatterers was designed to investigate the mechanical and sound insulation properties of CLT em-bedded with bamboo scrimber square cotters.The interlaminar shear strength,maximum positive stress,and static toughness coefficient of CLT short-beams with holes outside the mid-span face and those embedded with bamboo scrimber square cotters were investigated by the short-beam shear method.The influence of periodically arranged bam-boo scrimber square cotters on the sound insulation of CLT was studied by the impedance tube test method.The short-beam shear test showed that the square holes in the CLT reduced the interlaminar shear strength by 13.0%-16.5%.The embedding of the bamboo scrimber square cotters in the square holes increased the interlaminar shear strength of the CLT with square holes by 8.5%-12.7%,which resulted in a non-significant difference in the interlaminar shear strength between the CLTs with and without holes.The differences of maximal positive stress between the CLT with and without square holes were in the range of 24.52-29.45 MPa.The CLT with bamboo scrimber square cotters em-bedded in the square holes showed an increase in static toughness coefficients of 13.9%-19.1%compared to the CLT without holes.The sound insulation test results showed that the CLT embedded in bamboo scrimber square cotters was a local resonance phononic crystal structure.Single bamboo scrimber square cotters were spaced 25 mm apart at the top,bottom,left and right,and set in arrays in the CLT.The valley value of the sound reduction index with the anas-tomosis effect at 1 400 Hz was about 33.41 dB.Between 100 and 400 Hz,the sound insulation curve of the CLT em-bedded in bamboo scrimber square cotters showed a significant peak.The two-dimensional phononic crystal structure with bamboo scrimber square cotters as the acoustic scatterers increased the density of the CLT and the sound reduction index at low and medium frequencies with the increase in the side length of bamboo scrimber square cotters,where the sound reduction index below 600 Hz could be improved by 20.22%.It is feasible to enhance the sound insulation per-formance of CLT with bamboo scrimber square cotters without changing the thickness of CLT,with a small increase in density and no significant difference in mechanical properties.This research provides a scientific basis for reasonably utilizing CLT as important components in buildings where enhanced sound insulation is required.
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维普
