Design and performance evaluation of steel beam members with plate-type locally resonant metamaterials for vibration control

In this study, a plate-type locally resonant metamaterial (PTLRM) is proposed to control bending vibrations and low-frequency noise of civil members. Considering the ease of design, installation, and workability, the PTLRM was fabricated using high-density and soft materials. The PTLRM design includes a resonance frequency calculation of the unit and band gap estimation of the PTLRMs-coupled structure. Three indicators were developed and experimentally analyzed to evaluate the vibration attenuation performance of the PTLRM: the response suppression in the resonance of PTLRMs, peak response suppression ratio, and distance between peaks. Experimental results of a 5-m long steel beam with PTLRMs indicated that the bending modal responses of the steel beam were suppressed at frequencies closer to the local resonance of the PTLRM. This showed reasonable agreement with the results of the estimation. The acceleration of the PTLRMs-coupled beam was reduced by up to 98.58% in the frequency response function. The time history of acceleration also decreased significantly over the entire time period. The damping of the soft material had little effect on the bandwidth of the band gap. However, it was found that a proper increase in the damping of the soft material could increase the vibration suppression performance.