Low frequency bandgap characteristics and engineering application of phononic-like crystal metamaterial concrete
Metamaterial concrete is a new type of composite material with elastic wave bandgap characteristics,but its high bandgap frequency and narrow bandgap width limit its application in engineering mainly focused on low-frequency vibration control.Firstly,based on the theory of local resonance,this paper proposes a novel three-component cement-based phononic-like crystal model,and develops a phononic-like crystal metamaterial concrete based on this model.Secondly,the band structure,bandgap mechanism,and frequency response function of phononic-like crystal metamaterial concrete are calculated and analyzed,and indoor tests of phononic-like crystal metamaterial concrete are conducted.Finally,a phononic-like crystal metamaterial concrete subway track bed is prepared using the developed phononic-like crystal metamaterial concrete,and applied to practical subway engineering to solve the low-frequency vibration problem generated during subway operation.The results show that the phononic-like crystal metamaterial concrete opens 6 low-frequency bandgaps in the 200 Hz frequency band,and within the bandgap frequency range,the attenuation values are mostly above 10 dB,indicating a good attenuation effect.The phononic-like crystal metamaterial concrete subway track bed has a significant low-frequency vibration reduction effect in the 200 Hz frequency band.The maximum value of one-third octave insertion loss of the tunnel wall is 13.22 dB,the maximum vertical Z-vibration level difference of the tunnel wall is 5.052 dB,the maximum vertical frequency division vibration level difference of the tunnel wall is 5.926 dB,and the average vertical frequency division vibration level difference of the 4-200 Hz frequency band is 5.74 dB.The low-frequency vibration reduction effect is obvious.The relevant research results of this paper provide a new technical approach to solving the problem of low-frequency vibration in subway engineering and other engineering construction,breaking through the traditional vibration reduction control technology of civil engineering structures.
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